Small Scale Hydro Power

The views expressed in this Report are those of the authors of the papers and contributors to the discussion individually and not necessarily those of their institutions or companies or of The Watt Committee on Energy Ltd. Published by: The Watt Committee on Energy Ltd 18 Adam Street London WC2N 6AH Telephone: 01–930 7637 This edition published in the Taylor & Francis e-Library, 2005. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.” © The Watt Committee on Energy Ltd 1985 ISSN 0141-9676

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THE WATT COMMITTEE ON ENERGY REPORT NUMBER 15

SMALL-SCALE HYDROPOWER Papers presented at the Sixteenth Consultative Council meeting of the Watt Committee on Energy, London, 5 June 1984

The Watt Committee on Energy Ltd A Company limited by guarantee: Reg. in England No. 1350046 Charity Commissioners Registration No. 279087 MARCH 1985

Contents

Members of the Watt Committee

v

Members of Watt Committee Working Group on Small-Scale Hydro-Power

vii

Foreword

ix

Introduction

xi

Section 1

Potential for small-scale hydro-power in the United Kingdom E.M.Wilson

1

Section 2

Hydro-electric plant and equipment J.TaylorC.P.Strongman

8

Section 3

Civil engineering aspects N.A.Armstrong

37

Section 4

Institutional barriers E.C.ReedD.J.HintonA.T.Chenhall

48

Section 5

Economics of small public and private schemes A.T.ChenhallR.W.Horner

57

Section 6

Conclusions and recommendations J.V.CorneyH.W.Baker

78

Appendix 1

Sixteenth Consultative Council meeting of the Watt Committee on Energy

81

Appendix 2

Government grants and funding available P.J.Fenwick

83

Appendix 3

Use of water for milling or power generation: circumstances in which a licence is required

86

Appendix 4

National Association of Water Power Users: Paper for the Watt Committee

93

Appendix 5

Abbreviations

99

THE WATT COMMITTEE ON ENERGY The Watt Committee on Energy

102

Policy

102

Members of Executive, March 1985

103 103

Recent Watt Committee Reports

Member Institutions of the Watt Committee on Energy March 1985

* British Association for the Advancement of Science British Ceramic Society * British Nuclear Energy Society British Wind Energy Association * Chartered Institute of Building * Chartered Institution of Building Services * Chartered Institute of Transport * Combustion Institute (British Section) * Geological Society of London * Hotel Catering and Institutional Management Association * Institute of Biology Institute of British Foundrymen Institute of Ceramics * Institute of Chartered Foresters * Institute of Cost and Management Accountants * Institute of Energy * Institute of Home Economics * Institute of Hospital Engineering Institute of Internal Auditors (United Kingdom Chapter) Institute of Management Services * Institute of Marine Engineers Institute of Mathematics and its Applications * Institute of Metals * Institute of Petroleum * Institute of Physics * Institute of Purchasing and Supply * Institute of Refrigeration Institute of Wastes Management * Institution of Agricultural Engineers * Institution of Chemical Engineers * Institution of Civil Engineers * Institution of Electrical and Electronics Incorporated Engineers

vi

* Institution of Electrical Engineers * Institution of Electronic and Radio Engineers Institution of Engineering Designers * Institution of Gas Engineers Institution of Geologists * Institution of Mechanical Engineers * Institution of Mining and Metallurgy Institution of Mining Engineers * Institution of Nuclear Engineers * Institution of Plant Engineers * Institution of Production Engineers * Institution of Public Health Engineers Institution of Structural Engineers * Institution of Water Engineers and Scientists * International Solar Energy Society—U.K. Section Operational Research Society * Plastics and Rubber Institute * Royal Aeronautical Society * Royal Geographical Society * Royal Institute of British Architects * Royal Institution * Royal Institution of Chartered Surveyors * Royal Institution of Naval Architects * Royal Meteorological Society * Royal Society of Arts * Royal Society of Chemistry * Royal Town Planning Institute * Society of Business Economists Society of Chemical Industry * Society of Dyers and Colourists Textile Institute

* Denotes present and past members of The Watt Committee Executive

Members of Small-Scale Hydro-Power Working Group

J.V.Corney N.A.Armstrong

Institution of Civil Engineers, Chairman Institution of Electrical Engineers and Institution of Mechanical Engineers H.W.Baker Institution of Civil Engineers A.T.Chenhall Institution of Electrical Engineers D.J.Hinton Institution of Civil Engineers R.W.Horner Institution of Public Health Engineers M.J.Kenn Institution of Mechanical Engineers E.C.Reed Institution of Water Engineers and Scientists J.Taylor Institution of Electrical Engineers Prof E.M.Wilson Institution of Civil Engineers

Acknowledgements

Commander G.C.Chapman, Mr J.A.Crabtree and Mr O.M.Goring attended several meetings of the working group as representatives of the National Association of Water Power Users. The Watt Committee working group on Small-Scale Hydro-Power is indebted to many individuals and organisations in the United Kingdom from whom information and comments were obtained in the course of this project, including the Central Electricity Generating Board, North of Scotland Hydro-Electric Board, South of Scotland Electricity Board, regional Water Authorities and (in Scotland) regional councils and River Purification Boards. The Watt Committee on Energy acknowledges with thanks financial assistance by the Department of Energy, which helped to defray the costs of the proceedings of the working group, and the advice given by Dr P.J.Fenwick of that Department. Note The data included in this Report were correct, to the best of the authors’ knowledge and belief, in January 1985.

Foreword

At any moment in time the Watt Committee has four or five working parties, each tackling a specific project. Those under discussion at the meeting of the Watt Committee Executive of 24th January 1985 were technician education, waste disposal in the energy industry, the second phase of our study of acid rain and passive solar building design. Two other projects awaited firm proposals, and a further two were temporarily suspended because they would be more realistic at a later date. The present Report on Small-Scale Hydro-Power contrasts strongly with its two immediate predecessors, which dealt with nuclear energy and acid rain respectively.* It shares with them, however, the desire to clarify what at the moment could hold up development. Our only previous report devoted entirely to renewable energy sources was No. 5 Energy from the Biomass. Reports No. 1 and, to a less extent, No. 2 include sections on renewable sources; Report No. 4 Energy Development and Land in the United Kingdom contains two coloured maps showing alternative source distribution in the United Kingdom and suggests locations for wind, solar, wave, tidal and geothermal installations. Discussions with a number of individuals about small hydro-electric generating capacity suggested that it was something of a Cinderella in that it was unlikely to save much fossil fuel, and the cost per kilowatt could vary greatly with the site and with the amount of outside help that would be required. Furthermore, there was no simple statement of the legal obligations. Like windmills (now elevated to ‘aero-generators’), small hydro-power has suffered a long period of neglect illustrated by idle water-mills and mill-ponds used to supply fish rather than energy. A great deal of money has been spent on aero-generator design and a full-scale unit is under construction in the Orkney Islands. If it comes up to expectations we shall see more schemes being built and used to save energy. The same should be true of hydro-power. To add to this Foreword would mean drawing on the Report itself. I end, therefore, with my personal thanks and those of the Executive to the numerous

x

people who have given information, time and voluntary effort to add to our understanding of the problems and the wider potential of small-scale hydropower. February 1985 J.H.Chesters Chairman, The Watt Committee on Energy

* Particulars of previous Reports of the Watt Committee on Energy are given on pages 61– 62.

Introduction

Despite the abundance of sites in the United Kingdom where small-scale hydropower could be exploited, only a very small proportion of such potential is at present developed. The Watt Committee on Energy was concerned at this lack of exploitation of a valuable resource and therefore decided to establish a working group to examine the potential for development of further small-scale hydro-power as a useful addition to the energy resources of the United Kingdom. Its object was to identify obstacles which may have inhibited development in the past and to make suggestions for further study/action, with the eventual objective of helping to overcome the main obstacles and stimulate new schemes. The working group was free to make its own definition of what was implied by ‘small-scale’, and decided, in broad terms, that this should be any resource below the size which the electricity boards had themselves considered worth developing. In electrical terms we considered this to be from 5 to 5000kW. We also decided, in order to limit the field of our study, that we would not include wave or tidal power, as these could properly form the subject of separate studies. The papers forming this Report have been prepared by various members of the working group and explore the potential for small-scale hydro-power development in the whole of the United Kingdom. Topics covered include the technical problems and legal, institutional, environmental and economic aspects which may have inhibited development in the past. The working group has been greatly helped and encouraged by the information and assistance provided by members of the National Association of Water Power Users who have direct experience of constructing and operating small private schemes. The number and variety of such schemes provide concrete evidence of the practicability of such development. The members of this Association are enthusiasts and have for the most part constructed and operated their schemes themselves. Whilst clearly beneficial to their owners as they stand, they would not all necessarily satisfy current economic criteria. Our studies have been purposely limited to developments in the United Kingdom, but many aspects will be equally applicable to developing countries, particularly where a public electricity supply is not available in the vicinity and

xii

the choice lies between hydro-electricity or, as an alternative, diesel generation with high-cost fuel. The papers in general deal with water power for the generation of electricity, as it is in this form that it is easiest to assess its value as a power source; however, where an alternative use for the power exists it may be simpler to harness the power for such use, as was done in the past, rather than to use it for electricity generation. The technology involved in the development of water power is not new, but there are few people who have experience of both the engineering and the legal aspects, which are complex and varied. It is the hope of the working group that, by bringing together these subjects in one report, the problems facing potential developers of hydro-power will become better understood and many more successful schemes will result. J.V.Corney Chairman, Watt Committee Working Group on Small-Scale Hydro-Power


Section 1 Potential for small-scale hydro-power in the United Kingdom E.M.Wilson Department of Civil Engineering University of Salford Salford Potential for Small-Scale Hydro-Power in the United Kingdom

1.1 Introduction The United Kingdom is not a country rich in hydro-electric resources. Only in Scotland and Wales are there mountains and rainfall on a scale large enough to offer opportunities for hydro-electric development of tens of megawatts. However, over the whole country there are hundreds of sites where modest amounts of hydro-electric energy could be generated, at powers measured in tens of kilowatts. The problem of assessing potential requires, first, some arbitrary definition of what ‘small-scale’ means, since many of the surveys made in the past have considered schemes only if their power capacity exceeded fixed values, frequently in megawatts. So far as this paper is concerned, ‘small-scale’ means from 5 to 5000kW. An arbitrary sub-division can be made to mini- and microhydro, with capacities above and below 500kW respectively. During the last five years several studies have been made of small-scale hydropower in various parts of the U.K. These have supplemented many previous investigations: for example, there have been at least six sets of estimates of Scottish hydro potential in one form or another, though most of them did not include small-scale projects by the definition above. The range of such estimates reflects uncertainty about the premise on which they should be based. Francis, of the Department of Energy,1 has suggested that there are three broad categories in which estimates may be placed, namely: (a) Gross river potential is approximately the summation of annual runoff times potential head.

2 SMALL-SCALE HYDRO-POWER

(b) Exploitable technical potential is Category (a) less that energy which it is technically impossible to exploit; it includes, for example, losses due to efficiencies of plant less than 100%, and heads too low for available plant. Category (b) tends to move towards Category (a) with time. (c) Economic exploitable potential is Category (b) less the energy which it is uneconomic to develop. Economic circumstances differ from case to case, so there is no firm boundary separating Categories (b) and (c). Much depends on the cost of energy being displaced: for example, displacement of public supply at 4p/ kWh enhances the value of a scheme compared with sale to the Electricity Board at 2p/kWh. It is worthwhile to recall an extract2 from the Report of the Mackenzie Committee (1962) in assessing hydro-electric potential in Scotland: ‘To have any real meaning, the estimates of potential water power must be related to economic considerations…’ Most published studies deal with Category (b), and, since regional investigations cannot by their nature deal with site-specific details and economic analyses, guidelines based on minima for flow and head have to be adopted. In trying to assess the small-scale potential of a region the researcher has to use all the evidence he can find. For this paper, the existing hydro-electric capacity has been determined, together with published and unpublished assessments of further moderate potential; from these, an estimate has been made of small-scale potential. In the case of Wales and England there is better evidence, in the form of recent small-scale potential surveys,3,4 and these have helped in the extrapolations required. However, it must be said that in all that follows there is room for considerable error and the judgements made are inevitably subjective. 1.2 Hydrology Estimates of the occurrence and volume of flow passing a proposed hydroelectric site must be made if the development is to be properly sized and assessed. River flows are determined by the hydrology of the catchment and the consequent runoff and groundwater contributions. The river flow from a catchment is dependent upon area, location, orientation, rainfall, climate, topography and geology. In considering small hydro sites it is impracticable to consider all these variables in detail, and it is usual to resort to one of a number of estimating techniques. However, in some locations there may be an established Water Authority gauging station nearby where daily flow records over several years are available. Provided the gauging point (usually a weir or a calibrated river section) is not very far distant, a simple areal correction may be all that is required to adjust the measured flows to those at the required site. An HMSO publication5 details the location of established gauges—most are located on larger well-developed rivers. The local Water Authority may have

POTENTIAL FOR SMALL-SCALE HYDRO-POWER 3

additional gauges which could prove useful, and in every case an approach to the Water Authority is worthwhile to obtain flow data and to establish if there are any requirements for compensation flow. For run-of-river hydro-electric projects, the daily flow duration curve (FDC) provides the required data. The FDC shows the percentage of time that certain values of discharges are equalled or exceeded. Duration curves for long periods of runoff (in excess of 5 years) are utilized in deciding what proportion of flow should be used for generation, since the area under the curve represents volume and hence directly affects energy output. Figure 1.1 shows FDCs for the River Itchen at Allbrook, near Winchester, and the River Ogwen, near Bethesda, North Wales. The shape of the curve is also of importance: a generally flat curve represents a river with few flood flows, probably extensively supplied from groundwater; a steep curve indicates a ‘flashy’ river with frequent flood flows and comparatively low flows during dry weather. Such characteristics indicate the system of flow adjustment that is required to utilise the flows available. In cases such as the River Itchen where flows are relatively steady, a daily adjustment of flow may be all that is necessary. However, for ‘flashy’ rivers such as the Ogwen, continual flow adjustment may be necessary to utilise all that is available. In general, where there are no constraints on the scale of development, the 30% exceedance flow from the FDC may be adopted as a first estimate of the designed capacity for the scheme. Following the evaluation of costs, energy outputs and value of energy production for several capacities, both above and below that corresponding to the 30% exceedance flow, the design parameters may be modified to optimise the size of installation. For run-of-river sites, the FDC is fundamental to the calculation of energy output. Where long-term flow records at a particular site are not available, it is necessary to estimate the FDC from other readily available data, using an empirical method. Such methods of flow estimation depend on physical and climatic conditions affecting the catchment. Rainfall data are often utilised, as they are generally widely available and cover longer periods than river discharges. One such method is through the use of unitised FDCs.6 FDCs from established gauging points are unitised by dividing through the relevant catchment area and annual rainfall so that they represent flow from 1km2 of catchment with an annual rainfall of 1 metre. Such unitised curves can be used to represent the general flow conditions of a particular region. When applied to a specific catchment within that region, the unitised curve is factored by the appropriate catchment area and weighted annual rainfall. This method has the advantage that FDCs are produced from which energy can be directly calculated. The accuracy of the FDC produced is dependent on the similarity of the particular catchment to the gauged catchment, since even within the same region significant hydrological differences can exist.


Figure 1.1 Flow duration curves: river with few flood flows (left); ‘flashy’ river (right).

1.3 Scotland The first published estimate of hydro-power potential was that of the Water Resources Committee in 1921.7 The potential was estimated at 1700GWh per annum. This is the lowest of the Scottish estimates, probably because of the rudimentary nature of Scottish electrification in 1921 and, perhaps, the strong lobbying of non-resident Scottish landowners. In 1942, the Cooper Committee suggested a potential of 4000GWh per annum, and shortly afterwards the Hydro-Electric Development (Scotland) Act 1943 was passed setting up the North of Scotland Hydro-Electric Board (NSHEB). When NSHEB published its development scheme in 1944, it foresaw 102 projects producing 6270GWh per annum. This figure was revised again by Williamson,9 who suggested that the annual output could exceed 8000GWh. In 1962, the Mackenzie Committee reported a technically viable potential of 7250GWh per annum, and in 1981, with a resurgence of interest in hydro development—after a 20 year lull—NSHEB re-estimated the Scottish potential and concluded in a paper to the Economic and Social Research Council that the technical potential was 8500GWh per annum (2700MW installed) and that the


economic exploitable potential was 5100GWh (1630MW installed). Since this last study considered the lower power limit to be 50kW, it is clear that there is a large number of quite small sites in Scotland that have not yet been assessed. This is hardly surprising, since small schemes do not justify the transmission lines and access roads which are necessary in many parts of the country. From such evidence as exists already, it is probable that small-scale schemes in Category (b) with a total potential output of at least 180MW are technically exploitable, though the proportion of these which would also merit a Category (c) classification, as being economically viable, could only be an informed guess —perhaps a third, or 60 MW, producing, say, 260GWh per year. Table 1.1 Total potential hydro-electric power in the United Kingdom

Scotlan d Wales Englan d Norther n Ireland Total

Existing hydroelectric installations

Further major developments proposed but not built

Technically exploitable*

Economically exploitable*

Estimated small-scale (5kW–5MW) sites

MW

GWh/y MW

GWh/y MW

GWh/y MW

GWh/y

1270

4000

350

1100

180

790

60

260

120 9†

246 20

2308 –

390 –

70 32

300 160

25 14

110 75‡

Negl.

1

40

110

35

150

18

75

1399 4267 620 1600 317 1400 117 520 Notes * Power capacity estimated at 30% exceedance, which on most British rivers gives a 50% plant factor or thereabouts, †includes Kielder scheme (under construction). ‡These values reflect the high utilisation factors of water supply schemes, which are typically >60%.

1.4 Wales In Wales, as in England, public electricity supply is the responsibility of the Central Electricity Generating Board. The present installed capacity of CEGB hydro-power stations in Wales is 114MW, producing annually about 215GWh. In addition, there are Water Authority schemes totalling about 5.7MW, producing 41GWh per annum. The load factors represented by these figures, 0. 22 and 0.82 respectively, demonstrate only that the CEGB values peaking


capacity highly, whereas Water Authorities are using near-constant discharges to produce and sell energy to their Electricity Boards. The hydrometric areas covering Wales have recently been examined for their small-scale potential for the Department of Energy by Salford University.3 Some 565 sites were identified: they would have a combined capacity of about 70 MW and an annual energy output of 300GWh. The arbitrary lower power limit in this study was set at 25kW and the estimate of scheme capacities ranged from that figure to 3200kW, It is estimated that up to 50% of these sites might come within Category (c). 1.5 England The first published data about the hydro-electric resources of England were again those of the 1921 Water Resources Committee, which suggested an energy production of 180 GWh per annum. The Committee made it clear that this was by no means the total potential, which they were unable to estimate. A recent study4 of the English water industry commissioned by the Department of Energy, and again limited to powers of 25kW or above, has revealed 66 sites with power potential of 8.4 MW and potential energy of 48 GWh per annum. The economically exploitable proportion of these is indeterminate, but it may be about two-thirds. There are, in addition, certainly some hundreds of sites unconnected with the water industry that could be developed, and many others would generate powers of less than 25kW, the total of which has not been estimated since data are widely dispersed and have not been systematically examined. To provide a first indication, it would be reasonable to quadruple the water industry potential and to assume that one-third of these extra sites would be economic. These assumptions lead to Category (b) and (c) figures of 32MW, 160GWh and 14MW, 75GWh respectively. 1.6 Northern Ireland There has been no recent study of small hydro potential in Northern Ireland. More than 200 existing weirs are technically exploitable, but there are few examples where electricity is being generated. There are several excellent sites on the Six Mile Water and Blackwater Rivers which would almost certainly be economic also. The western part of Ulster was not fully developed for water power during the industrial revolution; nor were the upland sites on the Antrim plateau. It is estimated that there may be up to 100 new sites for small-scale installations. Based on topography, rainfall and comparison with similar areas more intensively studied, it would be reasonable to assume a technical potential of


about 150GWh per annum. This is equivalent to about 3% of current Northern Ireland electrical generation. A Category (c) figure might be about half of this. Two larger schemes on the Lower Bann and the River Mourne have been well researched and would certainly now be economic. They would have a total installed capacity of 40MW and would generate 110GWh per annum. 1.7 Summary The information given in this paper is summarised in Table 1.1. The estimates in this paper are based on the sources cited, on the references and on private communications from A.T. Chenhall and F.G.Johnson of the North of Scotland Hydro-Electric Board and Dr S.R.Cochrane of Queen’s University, Belfast, which dealt, respectively, with Scotland and Northern Ireland. It is now reasonable to assume that there are upward of 500 sites in the U.K. where small-scale hydro-power could be developed with a better-than-even chance of economic viability. References 1.

2. 3. 4.

5. 6. 7. 8.

9.

Francis, E.E. Small-scale hydro-electric development in England and Wales. In Conference on Future Energy Concepts, Institution of Electrical Engineers, London, Jan 1981. Electricity in Scotland: Report of the Committee on Generation and Distribution in Scotland. HMSO, Cmnd 1859, London, November 1962 (the ‘Mackenzie Report’). Department of Energy. Report on small-scale hydro-electric potential of Wales. University of Salford, Department of Civil Engineering, Oct 1980. Department of Energy. Report on the potential for small-scale hydro-electric generation in the Water Industry in England. University of Salford, Department of Civil Engineering, April 1984. Department of Environment. Surface Water: United Kingdom, 1976–80. HMSO, London, 1981. Wilson, E.M. Engineering Hydrology, 3rd Edition, p. 117. Macmillan, 1983. Report of the Water Resources Committee. HMSO, London, 1921. Hydro-electric works in North Wales. Further developments. Report to North Wales Power Company, September 1944. Freeman, Fox & Partners and James Williamson, 25 Victoria Street, London SW1. Internal Report No. 54. Williamson, J. Water power development in Great Britain. I.C.E. Joint Summer Meeting, Dublin, 1949.


Section 2 Hydro-electric plant and equipment J.Taylor and C.P.Strongman Merz and McLellan Newcastle upon Tyne Hydro-electric plant and equipment

2.1 Introduction The Watt Committee working group on small-scale hydro-power was set up to examine the potential for development of further low-head hydro-electric power as a useful and economical addition to the energy resources of the United Kingdom and to make suggestions for further study and action. When the working group discussed its terms of reference, consideration was given to extending its examination to overseas potential. A decision was made, however, to limit the study to development in the U.K., but with the thought that it would be welcome if, in doing so, the working group could encourage developments by U.K. plant and equipment manufacturers for which there might be sales opportunities overseas. Subsequently, the scope of the examination was changed from ‘low-head’ to ‘small-scale’ hydro-power, thus covering the entire head range of installations of small capacity. This Section of this Report is confined to the mechanical and electrical plant and equipment, although it excludes penstocks and gates (normally considered as part of the civil works) and the civil engineering aspects, statutory and legal matters, potential in the U.K., environmental considerations and so on, which are dealt with in other Sections. 2.2 Definitions There are many definitions of small-scale hydro-power, and it is not possible to be precise about them because the concept is somewhat subjective. The electrical engineer thinks of a definition in terms of the output of the generating set,

HYDRO-ELECTRIC PLANT AND EQUIPMENT 9

Figure 2.1 Vertical Francis turbine.

whereas the hydraulic engineer places more emphasis on head and flow, which define the selection and size of the plant and whose product gives output. The civil engineer, although inextricably bound by the head and flow, is also concerned with the physical dimensions of the plant and equipment insofar as they affect the design of the civil works. For the present purpose, it is proposed to consider a definition in terms of electrical output. Output of the generating set in the range 0–10MW, and even higher, has been quoted in several papers and publications; consequently there is a tendency to avoid defining what small-scale hydro really means—perhaps the International Electrotechnical Commission (IEC) should give some attention to this. The present working group decided to confine itself to an upper limit of 5 MW, largely because of the anticipated potential for future small-scale hydro-power in the U.K. Within this range other definitions are referred to, as indicated in Table 2.1, but there can be no hard and fast rule. Table 2.1 Definitions of hydro-electric schemes Small hydro Mini-hydro Micro-hydro

2–5MW 500kW-2MW 500kW


A further category was suggested by one source, namely pico-hydro, covering sets of 15 kW; but in fact there is no real logic in using ‘pico’—or indeed ‘micro’—unless these terms are related mathematically to the size of the plant. Although generating set sizes in the 15 kW range are not likely to be of interest to utilities for possible connection to the Grid,* such hydro-electric development should be encouraged. Many potential and existing private developers, such as members of the National Association of Water Power Users (NAWPU), find this to be a very useful range for domestic, farm and small local ‘cottage industry’ applications in rural areas of the U.K. This paper is confined to small-scale hydro-power installations designed for the generation of electricity. It is acknowledged, of course, that direct mechanical energy can be provided more cheaply than electrical energy. The concept of harnessing water for mechanical energy goes back for centuries, during which the water-wheel was used to produce small amounts of power for grinding corn and later was developed for direct-drive industrial uses: there remains a large number of old water-mills in the U.K. which could be developed. Indeed, many of them have been developed already, as publicised by NAWPU, and are used for stone-grinding, processing grain for animal feedstuffs, cornmilling, paper manufacture, flour-milling, snuff-grinding, the manufacture of cloth and textile products, wood working, forestry work, farm machinery etc. 2.3 General The technology of hydro-electric power is well established in the U.K., and includes plant that is in service, the design and manufacture of plant and consulting engineering services. The scope of the technology extends from small to large generating sets and includes their associated valves and ancillary plant. Manufacturers of plant such as water turbines, pump-turbines, waterwheel generators and generator-motors have supplied their equipment for power stations in the U.K. and abroad. Whereas many of the schemes were landmarks in hydropower development on account of size or design innovation, others were for ‘runof-the-mill’ schemes. There are numerous examples of plant that is now regarded as being in the category of small-scale hydro. Consulting engineering services for hydro-electric power have also been provided in the U.K. for many years. Again, a full range of types and sizes of scheme has been covered; notable major schemes have been engineered as well as small ones, the extent of the service and the design and engineering resources being adapted as required. Many of the small schemes in fact constitute the

* The legal and financial conditions for connection of private electricity generating capacity to the national public electricity supply network (the ‘National Grid’) are summarized in Sections 4 and 5 of this Report.


Figure 2.2 Horizontal Francis turbine.

initial power developments in the country or region. The associated plant and equipment can originate from companies abroad as well as from British firms; consequently, experience in the application of suitable plant is both shared and extensive. Examples of small-scale hydro-power installations in the range presently considered are numerous in Scotland, operated mainly by the North of Scotland Hydro-Electric Board (NSHEB) but also privately (for example, the aluminium works at Lochaber and Kinlochleven). There are also a few small schemes in England and Wales, but few in Northern Ireland. Most of the possible types and arrangements of generating plant are already well represented in the U.K. installations. Although some plants have been in service since the turn of the century, the 1920s saw an increase in activity; then, with the formation of the NSHEB in 1943, many small schemes were planned and installed until about the early 1960s. Currently the NSHEB is proceeding with a number of small run-ofriver developments. With regard to design and manufacture, most large generating-plant manufacturers in the U.K. also cater for the small-scale hydro-power market, and


Figure 2.3 Kaplan turbine.

there are smaller companies that specialise exclusively in this field. In view of the limited U.K. potential for the development of hydro-power, much of this plant has been manufactured for installation abroad. The selection of generating sets and plant for small-scale hydro-power applications is firmly based. Likewise, the selection of water turbines to suit the hydraulic conditions and of generators compatible with the loads or systems to which they are connected is made generally in accordance with established procedures. Nevertheless, there is scope for simplification and standardisation. This also applies to the ancillary plant. 2.4 Water Turbines All the available conventional types of water turbine are suitable for small hydropower applications. The most common turbines for low- to medium-head applications are the Francis and the Kaplan or propeller type. Apart from the vertical-shaft arrangement, the latter may be arranged as a bulb turbine, in which the turbine and generator are accommodated in an enclosure within the water passageway itself, as a tubular turbine, where the generator is located outside the water passageway, or as a straight-flow turbine (Straflo), in which the generator rotor is mounted on the periphery of the turbine runner. In addition, the crossflow turbine, which is a partial admission (impulse/reaction) type, can be used for low- to medium-head applications. For high-head applications, Pelton and Turgo impulse turbines, which can be supplied for very small outputs, are employed.


In the selection of the type of turbine there are overlaps between the different designs that can be adopted for a given head; therefore other factors, such as speed, submergence and efficiency, have to be compared. Other possibilities are centrifugal pumps in reverse rotation and marine bowthrusters (ships’ propellers). Further possibilities, such as river-current turbines and commercial lift hydro-engines, are at the experimental stage, and have been disregarded in the present study. 2.4.1 Francis turbine The Francis turbine (Figures 2.1 and 2.2) is of the reaction type, in which the runner receives water under pressure in an inward radial direction and discharges substantially in an axial direction. The main components of the Francis turbine are the fixed-vane runner, spiral casing, adjustable guide vanes and draft tube. The Francis turbine is suitable for a head range of about 10–300 m and ratings of 100kW. The shaft arrangement can be vertical or horizontal. 2.4.2 Kaplan/propeller turbine The Kaplan turbine (Figure 2.3) is an axial-flow reaction turbine and is basically a propeller type with adjustable blades. The water enters the spiral casing and after passing the runner blades flows through a draft tube to the tailrace. This type of turbine has a high efficiency over a wide range of heads and output and has a high specific speed. Governing is achieved by means of adjustable guide vanes and runner blades. The propeller turbine is similar to the Kaplan but does not have adjustable blades. 2.4.2.1 Bulb turbine With the bulb-turbine arrangement (Figure 2.4) the generating set is contained in a capsule accommodated in the water passageway. It is a very compact and selfcontained unit. There can, however, be problems with cooling the generator and access to the generator itself, although for small units the generator can be removed in its entirety for maintenance. For reasons of economy the generator must be of small diameter and therefore low inertia, thus limiting the application of bulb sets to connection with electrical systems of adequate size to maintain electrical stability. The bulb turbine is suitable for a head range of about 5–20 m and ratings of 300kW.


Figure 2.4 Bulb turbine.

2.4.2.2 Tubular turbines With the tubular turbine (Figure 2.5), the generator is located outside the water passageway with a long shaft drive and a simple seal arrangement; the generator is therefore easily accessible for maintenance. A gearbox can be accommodated between the generator and turbine if required to enable a high-speed—and thus cheaper— generator to be employed. It is suitable for heads up to about 15m and ratings of 50kW and upwards. 2.4.2.3 Straight-flow turbine The Straflo turbine (Figure 2.6) is a development of an earlier design in which the generator is located on the periphery of the runner; there is therefore adequate space for a large generator with large rotational inertia. The arrangement is compact, and there is no drive shaft. Consequently, the size of the water passageways, and hence the extent of the civil works, can be considerably reduced. This type of turbine is suitable for a head range of about 2–30 m and ratings of 500kW. 2.4.3 Cross-flow turbine The cross-flow turbine (Figure 2.7) is a radial/impulse type of low-speed turbine. Its dimensions at low head and high flow are greater than those of comparable conventional turbines. It has simple blade geometry and lower construction costs than the conventional turbine. For low heads, the blades can be manufactured


Figure 2.5 Tubular turbine.

from cheap materials because the bending forces are low. Efficiency is modest but the curve is flat over a wide flow range. Gear boxes can be employed to increase speed to suit economical generator designs; however, they reduce the efficiency. This type of turbine is suitable for a head range of about 2–200m and ratings up to about 1MW. Accordingly, it is quite suitable for the lower end of the microhydro range, because of its versatility and relatively low cost. 2.4.4 Pelton turbine The Pelton turbine (Figure 2.8) has an impulse wheel on which are mounted cupshaped buckets that have a radial partition or splitter in the centre to divide the impinging water-jet which issues from a nozzle on the end of the penstock. The wheel is encased to prevent splashing. The governing mechanism is an adjustable spear or needle and a jet deflector. This type of turbine is suitable for high heads — within the range 20–1000m—and ratings from 10kW upwards. For low outputs one or two jets would be employed and a horizontal shaft arrangement would be appropriate.


Figure 2.6 Straight-flow turbine.

2.4.5 Turgo turbine The Turgo turbine is an impulse turbine actuated by a water jet in which the water enters on one side of the runner and discharges at the other. It is suitable for heads of up to about 300m. The Hydec unit, manufactured by Gilbert Gilkes and Gordon Ltd. (see Table 2.4) is a turbine and generator package incorporating a Turgo water turbine. 2.4.6 Pumps running in reverse Conventional water turbines, as described here, with the exception of the ‘domestic’ types, are expensive compared with centrifugal pumps run as turbines. Consequently pumps running in reverse as turbines are commonly employed on micro-hydro installations in developing countries. This has prompted pump manufacturers to investigate the turbine characteristics of their pumps. Since a centrifugal pump lacks guide vanes, other means have to be used for starting, stopping and loading the set, for instance by adjustment of inlet-valve opening. Developments in this regard are taking place, and for sets using induction generators connected to the grid pumps run in reverse appear to be satisfactory. The lower runaway speed compared with a Francis turbine should give cost advantages.


Figure 2.7 Cross-flow turbine.

2.4.7 `Domestic turbines' Some manufacturers are turning their attention to the ‘domestic’ user sector, i.e. consumers in the range 10/15 kW. Although this is at the bottom of the range considered by the working group, the market, both in the U.K. and overseas, is likely to be substantial, but generally only for private purposes or for small rural communities. Indeed, a large majority of installations listed by the NAWPU falls into this category; none is connected to the Grid, undoubtedly because the costs of connection and of complying with the technical and other regulations could not be recovered. Other Sections of this Report refer to these institutional barriers. Of the 120 or so installations listed by the NAWPU, only three are gridconnected and these are sets in the range 80kW–100kW. Nevertheless, whatever their size and for whatever purpose they are built, they all contribute to the tapping of a renewable energy resource. Whereas the domestic range of turbines, some of which are made from engineering plastics, will no doubt be marketed at relatively low prices, they cannot be compared with the more conventional turbines in the upper range of set sizes considered here. The standards to which these turbines are manufactured and installed, although adequate for their purpose, may be somewhat different from those for an installation that might be designed to supply a local isolated community of several consumers for which a charge might be made and for which some cognizance would have to be taken of the various regulations. The


Figure 2.8 Pelton turbine.

domestic-type turbine referred to, when available, may well be competitive, both technically and economically, with standard pumps used as turbines. 2.4.8 Waterwheels Waterwheels—as stated earlier, in the past the traditional method of harnessing water primarily for mechanical energy —appear to be no longer manufactured except by a small firm in Cornwall. Many existing wheels have, however, been refurbished, some as museum pieces; but others have been put into service for generation and direct-drive purposes. 2.5 Generators Two types of generators are employed in hydro-electric installations: synchronous and asynchronous (or induction) type. In addition, for micro installations, standard induction motors may be employed.


2.5.1 Synchronous generators Synchronous generators are normally employed for generating sets connected either to an isolated system or a grid system. If they are connected to a grid, synchronising equipment is required. 2.5.2 Induction generators An important factor in the employment of asynchronous or induction generators, which are basically induction motors driven above synchronous speed, is the system to which the generator will be connected and the capability of that system to supply the necessary magnetizing power. The fact that the induction generator derives its excitation from the system and cannot therefore run completely isolated (capacitor bank excitation excepted) is a disadvantage where a suitable system is not available. It also suffers from the disadvantage that the natural inertia of the generator is considerably less than that of the equivalent, specially designed, synchronous generator. This can, however, be compensated for by adding a flywheel. These disadvantages are to some extent offset by the following important advantages. A separate excitation system is not necessary: this relieves the unit of sliprings, brushes, field circuit breaker, discharge resistor and automatic voltage regulator. Expensive synchronizing equipment is also not needed; the generator circuitbreaker is simply closed at or near synchronous speed and the machine pulls itself into step. As a consequence, the machine is generally without stability problems. Because of these factors the generator may require less maintenance than the equivalent synchronous generator; it is also cheaper. Its efficiency is somewhat lower than that of a synchronous generator, but this is relatively unimportant when considering hitherto uneconomic installations. There are speed and output limitations but they would probably not apply within the output range of small hydro. Although, generally, experience on induction generators of large size is limited, a number have been installed by the NSHEB in the range 50kW–5MW. 2.5.3 Standard induction motors The use of standard squirrel-cage induction motors, instead of the wound-rotor type, as generators is a possibility and, provided that care is taken to avoid overspeeding, this is a cheap solution for small-scale hydro-power. Overspeeding can be avoided by the use of overspeed release clutches.


Figure 2.9 Excitation systems: (a) static compound excitation; (b) brushless compound excitation. Figure 2.10 Basic governing system.

2.6 Excitation Systems and Automatic Voltage Regulators Existing types of excitation systems can be supplied to synchronous generators used for the generating-set range that is considered here. Such systems include shunt excitation using a controlled rectifier, compound excitation and brushless exciters. The choice depends upon the performance required.


For unattended machines thet supply a local load the selfregulating generatoris an obvious choise. In principle, it derives its excitation from the armature voltage and current of the generator via a compounding circuit. An important benifit of this arrangement is that excitation is sustained when the generator is subjected to ashort circuit. It is usual for a compound sysyem to include an automatic voltage regulator in order to achieve closer voltage control and assist rapid voltage correction following sudden load chnages. In the case of mini- and microinstallations, the excitation and regulation equipment can with advantage form a generator-mounted package. A brushless generator may also be preferred so that maintenance requirements are minimised (Figure 2.9). Larger machines, especially those connected to the grid, need an excitation control system matched to the requirements of the generator and supply system. 2.7 Governing The principles that apply to the governing of large hydro-electric generating sets are relevant to small sets. The objective is to maintain constant speed or frequency by controlling the turbine flow to match changes of load; it is assumed here that the plant is needed to supply an isolated system or local load, or to play a major part in the frequency control of a small system. Associated factors are the time taken to achieve the desired flow and the flywheel effect of the set. Governing requirements therefore have an influence on plant costs. In addition to their basic function, governors also facilitate starting, stopping, synchronising, parallel operation of generating sets and load sharing between them, and provide security against prolonged overspeeding. Should the small generating sets feed into a large system, governing may not be considered necessary, particularly in the case of induction generating sets. Then the governor actuator could be dispensed with, leaving the remaining mechanism to serve as an output or load controller. However, means for starting, running-up and shut-down of the set must still be provided. The main elements of governing systems (Figure 2.10), which apply equally to large and small hydro sets, and alternative possibilities are itemised below. 2.7.1. Governor system 2.7.1.1 Actuator The actuator is a stable device or mechanism located on the governor head which senses a speed change and converts it into the displacement of a collar or other component serving as a signal to an amplification system. The actuator can be


Figure 2.11 Oil supply for governing system.

driven directly from the set by gears or belt—which is common on very small sets—or by an electric motor supplied from a permanent magnet generator on the set. A variation on this is the electronic governor head, in which the speed signal, obtained from a toothed-wheel pick-up, is processed by electronic means. The output from the actuator is then applied to a hydraulic servomotor via a pilot valve. 2.7.1.2 Servomotor Since the forces available from an actuator are small (in relation to those required to alter turbine spears, deflectors, guide vanes, runner blades etc.) it is necessary to amplify by employing servomotors. These are controlled by a pilot valve with oil as the pressure medium. The servomotors can be single-acting, opposed by a spring, as often employed for Pelton turbines, or double-acting, as applied on Francis and Kaplan turbines. On micro sets and where the operating forces are reasonably low, independent hand-wheel control may be sufficient.


2.7.1.3 Pressure oil For spring-opposed servomotors, a storage receiver for the oil supply is not always necessary. For double-acting servomotors, providing large forces over a short operating time, pressure-oil receivers are needed (Figure 2.11). In both instances, a pumping set provides the pressure-oil supply. 2.7.2 Alternative possibilities 2.7.2.1 Output controller The application of a microcomputer to the output control of a hydro-electric generating set is an economical alternative to the conventional mechanical or electronic governor; this has been done by the NSHEB at Sloy power station. In addition to providing continuous control of the frequency and power output of the generating set, the controller can cater for sequential control of the run-up and shut-down operations and the monitoring of the plant. The output controller acts on the conventional servomotor equipment of the governing system. It is perhaps too early to say whether or not the microcomputer governor will match the reliability of the conventional mechanical or electronic governors. On the other hand, improved speeds of response can be achieved without loss of stability. 2.7.2.2 Load controller A wholly electrical system for speed governing that has recently been introduced for micro installations may possibly be extended to the low-power end of the mini-installation range (Figure 2.12). It is applicable to installations that operate independently of a public supply network or other parallel connected generators. Speed is regulated by maintaining constant active load on the generator. The flow through the turbine is constant at constant head at the full load value, and the available hydraulic energy is converted to electrical energy at all times, leaving no imbalance to cause significant speed changes. Any positive difference between generator output and supply-system load demand is absorbed in a dumping or ballast resistor. The only back-up that may be necessary is an inlet valve to isolate the turbine in the event of failure of the speed/load regulator or of a bypass valve. The ballast resistor and its regulator can take various forms. For example, discrete resistor sections can be selected by electromagnetic or solid-state switching; alternatively, a phase-controlled triac, or anti-parallel thyristor pair


Figure 2.12 Constant load controller.

with a single ballast resistor, may be employed. The regulator unit compares speed, and load, against fixed references to provide switching signals. Power dissipated in the ballast resistor need not be wasted. For example, water can be heated for use in a space-heating system or for a hot water supply. Even if the surplus energy has to be wasted, there will be no cost penalty, since for such an installation it has to be accepted that there must be a constant flow, which when not needed for energy would run to waste. Where water economy has to be practised, some form of secondary governing or water-flow regulator may be necessary if the normal demand is considerably less than the rated output of the machine. If sudden load increases of any significance cannot occur, or are not allowed to, such regulation can be quite simple. 2.7.2.3 Hydraulic brake The hydraulic brake incorporates a fly-wheel brake, on to which the water is diverted in the event of load rejection. The tendency to overspeed is thereby opposed and the rate of flow can remain constant. The system is applicable to impulse turbines. 2.7.2.4 Eddy-current brake An older form of electrical governing is the eddy-current brake, in which the load is adjusted to suit the output of the set. The power absorbed by the braking


device plus the system load equals the power output of the turbine. The braking device consists basically of a series/shunt-wound magnetic frame, similar to a d.c. motor, in which the main shaft revolves. On the end of the shaft a ferrous drum is mounted which rotates in the magnetic field set up by the frame. The shunt winding is connected to the generator terminals, and the eddy currents that are set up in the drum as it rotates absorb power and cause a braking effect. As the load on the generator varies, so does the current in the series winding of the braking device, partially neutralizing the shunt field. Accordingly, the power of the turbine is shared by the system load and the braking device. 2.7.2.5 Variable-speed operation An alternative method of electrical governing for small-scale hydro, now made possible by the development of large power static-variable frequency converters, is to allow the turbine to ‘free run’. This is a method adopted for wind-driven generators and considered for some wave-energy systems. The generators operate at variable frequencies according to the load, and the output is converted to direct current controlled at a constant value by a current regulator, and back again to alternating current (Figure 2.13). In effect, the power is transmitted to the a.c. system via a back-to-back d.c. link. The disadvantages are the need to vary a number of units to suit the constant flow as the load varies, the low efficiency at part load and the need to design for fairly frequent runaway conditions. 2.8 Electrical System Design In order to limit total costs and thus assist in the justification of small hydro projects, economies have to be made, not only in the selection of turbine, generator, governing and excitation, but also in the electrical system itself. Although a unitised system, comprising a generating set connected directly to its own step-up transformer, is common for most large installations, it is sensible and rational with small hydro-electric installations, if there is more than one set, to connect them through circuit breakers to a common busbar at generator voltage with a single step-up transformer to the transmission system. Not only is this cheaper than the unitised scheme, but it provides good operational flexibility. It should be mentioned that reactive power sharing is more easily accomplished with the unitised arrangement, however. When bussing at generator voltage, care must be taken not to exceed the fault-carrying and breaking capacity of the switchgear and connections; the method of generator earthing and protection must also be carefully studied. Off-site supplies for station auxiliaries can, however, be provided relatively cheaply.


Figure 2.13 Variable-frequency generator method of load control.

2.9 Protection When small generating sets are connected to an Electricity Board’s network, obligatory electrical protection is necessary to safeguard the network (Figure 2.14). This obligatory protection is set out in Engineering Recommendation G47/1 issued by the Electricity Council. In addition some guidance is given in Engineering Recommendation G26.*


Figure 2.14 Typical protection diagram for asynchronous generator connected to Grid. Asterisk (*) indicates obligatory protection.


Figure 2.15 Typical protection diagram for synchronous generator connected to isolated system.


For a micro-hydro installation connected to an isolated system, simple overvoltage, undervoltage and restricted earth fault protection would probably be sufficient (Figure 2.15). The great dilemma facing the developers of such an installation is that they may well find that the cost of protecting the plant is almost as expensive as the equipment that it is protecting. 2.10 Control Programmable sequence controllers/microprocessors are almost universally available for starting, stopping and controlling the generating set. They use programming languages that are relatively simple to understand and are userorientated, so commissioning and subsequent programme changes can be effected by the operating personnel. The use of microprocessors also reduces engineering and commissioning time, since control logic can be modified during the course of engineering and at commissioning without the need for wiring changes. The use of microprocessors can extend from simple start/stop control initiated by a single pushbutton operation to full remote operation, in which the generating sets can be controlled and monitored fully automatically by signals received from a central control command (if the station is connected to a grid system) or by means of local water level or flow detection equipment (if it is an isolated station). At present, micro-processors are relatively expensive for micro- or mini-hydro installations. For such installations, simple manual starting and stopping with the minimum of monitoring may be the right solution. However, if a microprocessor is employed it can carry out sequential control of starting and shutdown as well as continuous control of the frequency and power output of the generating set. It may therefore be economic for the upper range of small hydro installations. 2.11 Design and Engineering Large hydro-electric projects require specialists in almost every discipline of engineering. They are usually headed by a project manager, who supervises and coordinates these disciplines, with a team of engineers, each of whom is responsible for a section of the work. Careful monitoring of the engineering and progress in the manufacturer’s works and during construction, with computerised critical path scheduling and cost control, is necessary.

* Recommendation G59, revising these recommendations, is expected to become available about March 1985.


By contrast, this treatment cannot be given to small installations, as their capital costs are not sufficiently high to warrant expensive engineering management. Consulting engineers, specialising in hydro-electric project design and engineering, have therefore adapted to this situation by Table 2.2 Small hydro-electric installations in Scotland Station

Gross head, m

Plant Station capacity, kW

Gross head, m

Plant capacity, kW

Sron Mor

52

1×5000

14

1×160

Cuaich Loch Ericht

27 55

1×2500 1×2200

10 26

1×160 1×550

Mullardoch Achanalt Lochay

28 20 182

1×2400 1×2400 1×2000

Glenmoristo n Beannachran Loyne Tunnel Stronuich Pitlochry Orrin

10 14 42

Lubreoch

17 30

1×54 1×4000

Meig Dan Tobermory

15 42

Dalchonzie Lednock Ceannacroc Lairg Cassley

28 92 91 10 114

1×4000 1×3000 1×4000 1×3500 1×1 500

Luichart Torr Achilty Clunie Dam Elvanie Duchally

18 14 18 35 26

Striven Loch Gair Lussa Storr Lochs

124 110 117 138

Quoich Misqeach Kerry Falls Gaur

38 37 57 30

Kilmelfort

112

Invergarry

64

1×285

Mucomir

7

10

1×30

Kerry Falls

57

Vaich

7

1×320

Nostie Bridge Loch Dubh (Ullapool) Morar

151

2×3000 2×3000 2×1200 2×950 and 1×800 1×2000 and 1×83 1×1750 and 1×200 2×500 and 1×250 2×625

1×210 1×50 1×200 and 1×56 1×76 1×200 and 1× 80 1×85 1×100 1×175 1×300 1×325 and 1× 125 1×350 1×350 1×500 1×160

Culligran

60

1×2000

167

2×600

Gorton

79

1×100

6

2×375

Errochty

92

1×525


Station

Gross head, m

Plant Station capacity, kW

Gross head, m

Plant capacity, kW

Chliostair (Harris) Gisla (Lewis) Shin Awe Barrage

126

2×500

Claddoch

197

1×100

48

1×540

*Bonnington

–

2×5000

6 1×100 *Stonebyres – 2×3000 7 1×433 The schemes listed here are those operated by the NSHEB and SSEB that give output of 5 MW and below. * South of Scotland Electricity Board.

employing a small number of experienced staff on these projects, so as to eliminate time spent on optimisation of alternative designs: the choice is left to the general engineering experience of the engineers assigned to the work. Simple specifications together with standard conditions of contract should also be employed. This reduces not only the manufacturer’s works and construction costs but also tendering costs. Clients also have a responsibility for keeping the engineering costs of an installation to a minimum. Some may get deeply involved and place heavy demands on the man-hours allocated to the engineer responsible for the design. In addition, much time and expenditure can be wasted in discussion of the technical requirements with the public utility to whose grid the installation may be connected. For example, the interpretation of obligatory protection requirements may have to be set against different system configurations. The Recommendations of the Electricity Council, referred to in section 2.9, are by no means clear and definitive for every situation, and developers have found that the adoption of these Recommendations is time-consuming. For auxiliaries systems, it is not always possible to simplify the specifications to the same extent as for the generating sets, since details of auxiliaries circuits have to be calculated and scheduled irrespective of the size of the generating set —except perhaps for micro-installations. There is, however, considerable scope for producing what have come to be regarded as ‘mini-specs’. 2.12 Conclusions To summarise, the turbine type is determined by the hydraulic conditions, operating requirements and economic considerations. Standardisation of water turbines in general is difficult because they are ‘sitespecific’, and it is rare that site conditions match those which are best for a standard turbine. However, for micro installations there is a case for giving serious consideration to standardisation, since the plant and equipment represent


Figure 2.16 Cost envelopes.

a large proportion of the total cost and these costs can be reduced by some measure of standardisation—even though some sacrifice in operational flexibility and efficiency may be the consequence. Such standardisation might extend to the


selection of materials and of runner sizes for specific head ranges, resulting in standard casings, shaft and bearing arrangements etc. With regard to generators, whenever possible only standard generators should be specified. The employment of standard induction motors run as generators should be considered for grid-connected mini- and micro-installations. Where small synchronous generators are employed, the self-regulating set or a brushless system may be the best solution for the excitation. For the mini- and micro-range of sets, manual start-up and stopping with appropriate auto-trip facilities should be adequate. A micro-processor may possibly be employed, however, to cater for sequential starting and stopping and continuous frequency and power output control if the cost is right. Protection of the installation should be as simple as possible and the minimum necessary to safeguard the plant. If the sets are grid-connected, cognizance must be taken of the Electricity Council’s Recommendations. From studies made, the future development of small-scale hydro in the U.K. is likely to be mainly in the mini- and micro-hydro range of set sizes and the summary and conclusions (Section 6 of this Report) have been biased towards this. Whilst Section 2 is confined to small-scale hydro in the U.K., it is recognized that in developing countries a considerable degree of improvisation in hydro-electric engineering is practised. It is unlikely, however, that such improvisation would be tolerated in the U.K. for grid-connected installations. Finally, what are the costs of the electrical and mechanical equipment associated with small-scale hydro?—an easy question to ask, but a difficult one to answer. Much depends on the country in which the equipment is manufactured and installed. If it is in a developing country, with relatively inexpensive labour, it will be cheaper than in a developed country. Indeed, U.K. manufacturers are known to arrange for some of their heavy engineering and sub-assembly work to be done in the Far East because of the high cost of labour in Europe. Figure 2.16 indicates the form of cost envelope, showing cost per kilowatt plotted against set output across the head range. The curve has been derived from actual installation costs and budgetary information provided by manufacturers and public utilities in the U.K. It does not pretend to be definitive, and many installers will say that the work could be done much more cheaply. These claims must, however, be measured against the institutional barriers that may or may not apply; the standards of engineering that are set also affect the cost. The cost curve illustrated in Figure 2.16 most certainly does not claim to represent the installer who buys a small ‘domestic’ turbine for private use: he is not bound to provide sophisticated control and protection requirements, and may not be hampered by too much bureaucracy. As to the costs of installations in the U.K. that are connected to the Grid, the envelope of costs shown in Figure 2.16 is realistic.


Table 2.3 Small hydro-electric installations in England and Wales Station

Plant capacity, kW

Cwm Dyli

1×2000 1×1000 1×2000 Dolgarrog 1×5000 1×5000 Mary Tavy 3×220 2×650 Morwellham 2×320 Chagford 1×31 The schemes listed here are those operated by the CEGB that give output of 5 MW and below. Table 2.4 Suppliers of water turbines in the United Kingdom Supplier

Address and telephone number

Types of turbines

Boving & Co. Ltd.

Villiers House, 41–47 Strand, London WC2N 5LB (01) 839 2401 Canal Iron Works, Kendal, Cumbria LA9 76Z Cathcart Works, Glasgow G44 4EX (041) 637 7141 Cambridge Road, Whetstone, Leicester LE8 3LH (0533) 863434 Ringwood, Hampshire BH24 1 PE (04254) 2405 Mill Lane, Island Road, Ballycarry, Co. Antrim, Northern Ireland (09603) 78610 Ajax Works, Whitehill, Stockport, Cheshire SK4 1NT (061) 4806507 Forest Road, Grantown-onSpey, Morayshire, Scotland PO Box 2, Luton LU1 3LW (0582) 31144

Francis; Pelton; Kaplan; Propeller; Tubular

Gilbert Gilkes & Gordon Ltd. Weir Pumps Ltd. GEC Energy Systems Ltd.

Armfield Engineering Ltd. Newmills Hydro Ltd.

F.Bamford & Co. Ltd.

MacKellar Engineering (Grantown-on-Spey) Ltd. Hayward Tyler Pump Company Evans Engineering & Power Company

Priory Lane, St Thomas, Launceston, Cornwall PL15 8DQ

Francis; Pelton; Turgo Impulse; Hydec Francis; Pelton; Tubular; Reversed pump; Kaplan Francis; Pelton; Kaplan; Propeller; Deriaz; Tubular Francis; Pelton; Crossflow; Kaplan Francis; Pelton; Propeller (Kaplan); Turgo Impulse

Propeller (Kaplan); Tubular; Francis; Pelton (micro) Micro-hydro propeller; Cross-flow; Pelton Reverse pump (submersible generator and other types); Pelton Reaction and impulse turbines up to 100 kW; water turbines (under 1200


Supplier

Flygt Pumps Ltd. Dorothea Restoration Engineers Ltd.

Portmore Engineering Ltd.

Swift Industrial Developments Ltd. Water Power Engineering

Westward Mouldings Ltd.

Address and telephone number (0566) 3982

Colwick, Nottingham NG4 2AN (0602) 614444 Southern Works, 68 Churchill Road, Brislington, Bristol BS4 3RW (0272) 715337 Portmore Road, Lower Ballinderry, Lisburn, Co. Antrim BT28 2JS, Northern Ireland (0847) 651528 PO Box 8, Romsey, Hampshire SO5 OGT (0794) 40714 Coaley Mill, Coaley, Dursley, Glos. GL11 5DS (0453) 89376 Greenhill Works, Deleware Road, Gunnislake, Cornwall

Types of turbines kW); U.K. Patent holders for electronic loadgoverning systems Submersible propeller Reconditioned Francis turbines

Cross-flow

Axial flow impulse with flow control Cross-flow; Reaction; Second-hand and overhauled turbines Water-wheels

Disclaimer. The particulars given in Table 2.4 are given in good faith, but the Watt Committee on Energy takes no responsibility for their accuracy or for any omissions or for the fitness of the equipment listed either generally or in any specific scheme. Developers should discuss their requirements with the suppliers and seek appropriate advice.

In Tables 2.2 and 2.3, small hydro-electric installations (5MW and below) operated by the NSHEB and CEGB respectively are listed. In addition to these, a large number of private hydro-electric installations in the U.K. operate at heads from about 0.5m to 220m and outputs between 1.5 kW and 200kW: among them, most of the recognised turbine types are employed. Only two or three of these are connected to the electricity boards’ systems. The remainder are used for private purposes only, and some have direct drive applications. NAWPU can supply reasonably complete lists of them. Details of suppliers of water turbines in the U.K. are given in Table 2.4. The authors are indebted to the Partners of Merz and McLellan and to their colleagues in the firm, as well as to the other members of the working group, for their valuable help in the preparation of this paper.


Bibliography 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Water Turbines for H-E Power. Gilbert Gilkes and Gordon, Kendal, 1974. Small Hydro-Power Fluid Machinery. Winter meeting of American Society of Mechanical Engineers. Chicago, Illinois, USA, 1980. The Power Guide. Intermediate Technology Publication, 1979. Gaal, V. et al. Small hydro-electric power stations—a contribution to the solution of the energy problem. Brown-Boveri Review. July/August, 1983. Gordon, J.L. Small hydro puts new challenge to consultants. Energy International, August, 1980. Wilson, E.M. Small scale hydro-power developments in the U.K. World Energy Conference, New Delhi, 1983. Micro Hydro Developments. Hydro Power, December, 1980/January 1981. Energy Department gives qualified ‘Yes’ to small hydro. Electrical Review, April, 1979. Teichmann, H.T. International standardization of small hydro schemes. Water Power and Dam Construction, May, 1983, Generating profits on a small scale. The Engineer, 11/18 August, 1983. Giddens E.P. et al. Small hydro from a submersible pump. Water Power and Dam Construction, December, 1982. Generators for small hydro applications. Hydro Power, December, 1980/January, 1981. Pereira, L. Induction generators for small hydro plants. Water Power and Dam Construction, November, 1981. Water Power from Weissenburg-Ossberger-Turbinenfabrik GmbH. Garman, P. Development of a turbine for tapping river current energy. Appropriate Technology, September, 1981. Submersible generator. Electrical Review, 23 September, 1983. Friedlander. Reviving low-head and small hydro. Electrical World, August, 1980. Makansi. Equipment options multiply for small-scale hydro. Power, May, 1983. Small hydro needs its own experts. Water Power and Dam Construction, December, 1982. Marshall, A.F. et at. Microcomputer control of hydro turbines. Proc. I. Mech. E., April, 1983. Nair, R. Development potential for low-head hydro. Water Power and Dam Construction, December, 1982.


Section 3 Civil engineering aspects N.A.Armstrong North of Scotland Hydro-Electric Board, Edinburgh

Civil engineering aspects

In most cases, the end-product of a hydro-electric scheme is electricity produced by the generator and driven by the turbine prime mover. Although the generating plant is vitally important, it is nevertheless usual that the major part of the capital cost of a hydro-electric scheme is absorbed by its civil engineering aspects. This Section brings to the attention of the developer of a potential small hydro-electric scheme the salient questons of civil engineering to which he should be giving consideration when assessing the feasibility of the scheme. 3.1 Aqueducts There is a large variety of types of hydro-electric schemes. The upper end of a typical scheme (Figure 3.1) is dealt with first here, and other aspects are dealt with progressively, working downstream to the tailrace, the civil aspects of most of the types that are normally encountered being briefly described. The beginning of a conventional hydro-electric scheme is at a point where water collects, usually a loch or lake, a headpond or a river, providing a head of water. This is what the developer has noticed to make him interested in its potential for power development. This collection point is fed by run-off from rainfall or snow, falling over its upstream catchment area and draining naturally until it reaches this point. It is often possible, and if so generally worthwhile, to increase the amount of natural water that is available by tapping adjacent catchment areas that would not naturally drain into the selected point. This is usually done by constructing some form of aqueduct system. A first basic point for the developer, therefore, is that the aqueduct system will almost certainly require planning permission.


Figure 3.1 Main features of typical scheme.

Next, if it is relatively small and does not create a safety hazard for people or livestock, the aqueduct can be left open; otherwise, it requires to be either covered or fenced (Figure 3.2). A buried aqueduct eliminates these hazards, and overall is generally less expensive. An open aqueduct’s gradients should permit the water to flow at a reasonable speed to achieve a self-cleaning capability if grit, debris or stones can gain access; if the rate of flow is slow, the aqueduct is liable to become blocked and to overflow, particularly on curves or bends. The presence of large boulders which could readily block the aqueduct if they enter the system should be checked with care. Consideration should be given to making the aqueduct as impermeable as possible by lining it with suitable material, such as slate, flagstones, granite slabs, bitumen, concrete or steel plate etc. Problems may arise if the aqueduct is open and liable to spill; this might seriously affect its banking, which could then be breached and far progressively. Provision should therefore be made to allow the aqueduct to spill automatically at predetermined points so that excessive water is ejected safely. Alternatively, if possible, the amount of water allowed into the aqueduct system may be limited; for example, the aqueduct may be fed from a river through a pipe which limits the entry of water. A rough guide to the size of the aqueduct, if it feeds a storage reservoir, is that it should be capable of handling five times the average flow of water. It may be necessary to bridge the system where it is crossed by rights of way.

CIVIL ENGINEERING ASPECTS 39

Figure 3.2 Concrete-lined aqueduct, with bridge for sheep.

A last consideration with regard to the aqueduct is the possibility of tunnelling to tap an adjacent catchment area. Tunnelling is likely to be expensive. The minimum practical tunnel diameter is approximately 2m, and the current cost of construction is around £1000000 per kilometre. 3.2 Storage Reservoir The provision of the storage reservoir may necessitate the building of a dam. The most important aspect of this in the U.K. is whether it is liable to come within the terms of the Reservoirs Acts. At present, the Act in force is the 1930 Reservoirs (Safety Provisions) Act.1 A new Reservoirs Act was passed in 1975, but its first phase is only now being brought into operation. A reservoir comes within the scope of the new Act if its stored water exceeds 25000 m3 (883000 ft3 or 5500000 gallons) in volume. This is about the same as the quantity of stored water that came within the scope of the 1930 Act. It is not a large quantity: for example, if the average depth of the reservoir were 3 m, the dimensions of the area containing this volume would only be around 90 m×90 m. Every new dam that is subject to the Reservoirs Acts has to be designed, and its construction must be supervised, by a civil engineer from a panel appointed by, for England, the Secretary of State for the Environment, and the Secretaries


of State for Scotland and Wales, and on completion a certificate is issued. A list of the appointed engineers can be obtained from the Institution of Civil Engineers1 or the Department of the Environment.3 The dam must then be inspected not less than once every 10 years, again by an engineer selected from the panel of appointed engineers. A new feature of the 1 975 Reservoirs Act is that every dam that is subject to the Act is required to have, in addition to the 10-yearly inspecting engineer, a supervising engineer selected from a further panel of appointed engineers;1,3 he is appointed to keep a watchful eye on the dam and to ensure that any recommendations made at the inspections are carried out. He reports to an enforcing authority. In Scotland this is the local regional or islands council, and in England and Wales it is the Greater London Council or appropriate county council. From 1 April 1 986 it will be necessary for all undertakers of large raised reservoirs to appoint a supervising engineer and to be responsible for payment of his fees in respect of each dam that he supervises. It is probable, in the case of a supervising engineer’s duties, that the payment, including travel and other expenses, for a dam inspection at the present time can be expected to be in the region of £1000 to £1500. 3.3 Dam Small dams are usually constructed on the gravity or embankment principle (Figure 3.3) and are of earth or rockfill. The type of dam selected may depend on its locality: for example, there may be a ready source of suitable material nearby. Alternatively, the type of dam may be determined on environmental grounds if it must be of a type that blends with the surrounding terrain. The likely severity of floodwater could be another influence on the choice: for example, a concrete gravity dam might be considered superior to an embankment dam. An embankment dam requires a waterproof membrane. If the dam is relatively small, the membrane could be a simple wall with fill on either side; it would also require an upstream protection face, such as stone or rock, to counteract any eroding wave action. Some possible weaknesses of an embankment dam are as follows. (1) There is a danger that the dam may be overtopped with flood water, which could then affect its vulnerable downstream face. (2) If it is necessary to have an opening through the dam for flushing out gravel and stones etc., the opening could create a permanent potential source of leakage. By contrast, the small concrete gravity dam does not suffer these problems: it can probably be constructed using standard deliveries of ready-mixed concrete but care is needed to ensure that it is well founded on bedrock to prevent its being overturned.


Figure 3.3 Embankment dam prior to installation of 1-m high top wave-wall gabions.

A serious operational problem could be the build-up of gravel, sand etc. behind the dam, especially in river schemes. The scheme must therefore incorporate means to flush out this material. Usually this is done by running a culvert through the dam, with a flushing gate. The gate can be on either the upstream or the downstream face of the dam; if the gate is on the upstream face, it may be difficult to clear gravel from the gate’s tracks, and this might prevent it from operating correctly; if on the downstream face, the culvert is always under full pressure and water will certainly ultimately find any weakness. The following are practical suggestions if it is proposed that the dam shall scour through a culvert. (1) The culvert can be continued upstream of the dam to act as a scouring channel. (2) The optimum gradient is 1:20. (3) The width of the culvert should exceed its height by a ratio of about 5:3. It is important to ensure that when the gate is opened water does not prevent access for the purpose of reclosing the gate.


(4) When scour is operated, the rate of flow must not be too low; otherwise, gravel may collect under the gate and consequently it will be difficult to close it. (5) Conversely, if the rate of flow is too high, only local scouring will take place around the entrance to the culvert. (6) Some arrangement should be made to enable the dam to be deliberately drained. Dams must be designed to cope with floodwater—by discharging usually over a spillway, or occasionally by opening gates. Guidelines for the quantity of floodwater for which the design of the dam must provide are contained in a Floods and Reservoir Safety booklet,2 published in 1978 and obtainable from the Institution of Civil Engineers. Although its recommendations are not mandatory, the inspecting engineer would generally expect its requirements to be met. The guide requires that the dam be categorised as follows: (a) by location, that is, in terms of the risk to life and property downstream; (b) by type, that is, in terms of its ability to withstand overtopping. The booklet gives guidelines on the period of time in years which, once the dam has been categorised, must be considered for determining the maximum possible flood that may occur. The longer the period, the more severe the flood that can be expected. A small dam would possibly be based on a 150-year flood, or on an even shorter period if the affected community is small and the risk negligible; but a dam may be required to contain a 10000-year flood, or even more, if a community with a higher density would be at risk. The probable maximum flood (pmf) that can be realistically expected at the dam is dependent on the probable maximum precipitation (pmp), rain plus snow if applicable, for a given duration over the relevant catchment or drainage basin under the worst flood-producing conditions in the catchment area. Using these data, the booklet provides guidelines on the amount of flood water that the dam must safely discharge. If in any circumstances the dam would prevent water from going down the residual river section (between the dam and the place where the power station is located), it may be necessary to discharge ‘compensation water’—that is, to make good the shortage of water in that section of the river. This could be to meet fishery requirements or to maintain a summer amenity, for which the river bed must be kept wet and fresh. About 5% of the average flow is normally considered to be an adequate discharge for these requirements. 3.4 Pipeline If the water is conveyed to the power station through a pipeline, the cost can be relatively expensive. Nevertheless, a good choice of types of pipes is available. It


Figure 3.4 Fibre-glass penstock pressure pipe; diameter, 0.4 m.

may be necessary to bury the pipeline for reasons of amenity. A small hydroelectric scheme may have the pipeline above ground: that requires the construction of supports. Pipes suitable for small-scale hydro-electric schemes may be of steel (to BS 3601), ductile cast iron, glass fibre, reinforced plastic or asbestos cement (to BS 486). Steel pipes are the commonest. The pipes are usually internally protected by a spun bitumen or epoxy pitch coating. If below about 1m in diameter, they are difficult to recoat internally, as a painter cannot readily gain access. Corrosion effects can be reduced if the pipeline is always full of water, but steel pipes require periodic attention to contain corrosion. Standard sizes are available —up to 2m in diameter—but there is no limitation on size. The working pressure of the available pipes is virtually unlimited. The pipe joints may be flanged or welded, or Viking Johnson couplings may be used. Supports are required about every 12m for an above-ground pipeline. The painting of a steel pipeline requires some care. If a bitumen type of paint is used, the pipes may require to be recoated internally every 5–8 years. The paint should last longer if it is applied by means of a spun bitumen process— that is,


when applied to new piping. A bitumen coating usually suffers abrasion damage, particularly on the base. When repainting, it is often difficult to apply the paint to the invert owing to leakage and condensation, even when dehumidification equipment is used. External paint has a life of around 12–15 years; the more sunlight it is exposed to, the shorter its life. Normally, micaceous iron oxide paint is used. Ductile cast iron pipe is now becoming a very serious competitor: it is available in standard sizes up to 1.6 m in diameter. Its working pressure is suitable for a head of around 250m of water at <1.2-m diameter and for a slightly lower head at a larger diameter. It is either flanged or has an O-ring spigot and socket. Its anti-corrosion characteristics are good. Supports are required every 5– 8 m. Glass-fibre reinforced plastic pipe is available in standard sizes at up to 2m in diameter. Its working pressure is around 160m head if used above ground and 200 m if buried; higher pressures are possible. The joints are either O-ring spigot and socket or Viking Johnson coupling. This kind of pipe requires to be supported at intervals of 3–5m. Its advantages are that it is light in weight and easy to erect, that it can be transported in long lengths, so fewer joints are involved, and that it is non-corrosive. Its disadvantages are that it may be prone to accidental damage and may degrade with age, particularly if exposed to sunlight, and that any repair costs could be high. Asbestos cement pipe is available in standard sizes to about 1.2-m diameter with working pressures to around 120-m head. It is joined by sleeve couplings with an O-ring. It requires to be supported at 4- to 5-m intervals. It is liable to be easily mechanically damaged if installed above ground, so is better buried. Concrete pipe is available. One type has a steel core with a spun concrete lining and a prestressed mortar casing. It is available with diameter < 1.4 m and a working pressure of 120-m head at 1-m diameter and 60-m head at the largest diameter. In a hydro-electric scheme, the possible reason for concern about this type of pipe is that a faulty section of the concrete lining might come adrift and damage the turbine. The delivered cost of these various pipes is surprisingly uniform—within a range of some 20%. The ductile cast iron type is the least expensive. Delivered cost to the north of Scotland is about £ 100 per 1-m length for a pipe of diameter 1m. The NSHEB has one glass-fibre reinforced plastic pipe in service (Figure 3.4). This is a pipe of diameter 0.4 m under a head of 70 m and some 1000 m long, installed in 1 962 to replace a corroded steel pipe that had been in service for almost 40 years. Plastic was chosen because of the difficult road access, and the plastic pipes were in fact taken to the site by helicopter. The only operational trouble experienced was in the jointing—a spigot-and-socket type with a plastic fill— which had cracked as the result of thermal expansion and contraction effects when the pipe was left empty for a length of time. The new pipe, as installed,


Figure 3.5 Concrete intake dam, incorporating self-cleaning overshot screen.

was in fact too rigid; once that problem had been cured, it has given excellent service. For the occasions when a pipe is filled or emptied, means must be incorporated to allow the ingress or egress of air. This is especially important during emptying—either planned or accidental—to avoid the danger that the pipe may collapse as a result of vacuum effects. 3.5 Screens Screens are generally installed upstream and at the intake of turbines, but are also needed on occasions at the discharge of turbines for fishery requirements. They are installed for the two following basic reasons: (1) To prevent debris—leaves, grass, twigs, heather roots, stones etc.—which may block the passages of the turbine, especially the jets of Pelton and Turgo turbines and the guide vanes and runners of Francis turbines. This blockage


causes reduction in output, and it is time-consuming to dismantle the turbine to clear it. (2) To prevent access by fish to the turbine (if fish regulations are in force). The area of screening in this case must be large enough for the flow-rate of the water to be kept down to the region of 0.25–1 m/sec. The spacing of the screen is dependent on the size of the debris that can be permitted to go through the turbine and the size of fish to be encountered. Screens have to be cleaned. This can be a particularly onerous and timeconsuming task, especially in the late Autumn. It may be advantageous to install an oversize area of screening so that the frequency of cleaning is reduced. For the operator of a small hydro-electric scheme to have to rake out the screen in the middle of the night is no fun! Hand-raking is usual on small schemes. Trash rakes are available, but they require manual supervision; at least one firm produces a relatively inexpensive automatic screen-cleaning device, however. A particularly troublesome problem is presented by the debris carried in aqueduct systems. Aqueduct intakes can be designed as self-cleaning devices by allowing the water to pass through a slightly upward- or downward-sloping screen. This traps the debris, which is then pushed up or down the screen by the water-flow or by gravity. Eventually the debris tips over the end of the screen, and it is then led to an area away from the path of the water (Figure 3.5). An upwardsloping screen can be used where there is an abundance of water, as in a river supply. 3.6 Power Station To house the generator and associated equipment, the power station can be a fairly simple structure, but it must be weather- and vandal-proof (Figure 3.6). The foundations for the machinery are relatively straightforward, although it should be kept in mind that it is rotating machinery that they support, so there may be a certain amount of vibration. It may be necessary to install some form of crane or lifting device within the station. The station should be on a site where it is not liable to be flooded by external water. If possible, arrangements should be made for the station to drain automatically if an internal pipe fractures: this ensures that the generator, bearings, control panels and electrical gear are not submerged, as repairs in this event would be lengthy and costly. The water from the turbine is discharged along a simple channel or tail-race. It may be necessary to fit a gate at this point to prevent back-flooding of the station if the turbine is dismantled for overhaul or repair. Two final basic points for the developer of a small hydro-electric scheme are that he should take into consideration the siting of the station for road access, and if he proposes to feed excess electricity into the National Grid a suitable grid connection point must be relatively close.


Figure 3.6 Compensation water-power station, housing 350-kW horizontal Francis machine operating under head of 32 m automatically controlled by headpond level equipment.

References 1.

2. 3.

Reservoirs (Safety Provisions) Act 1930 (includes Reservoir Floods Standard). Reprinted 1960, 70 pp., Institution of Civil Engineers. Thomas Telford Ltd., 1–7 Great George Street, Westminster, London SW1P 3AA. Floods and Reservoir Safety (an engineering guide), 58 pages. Institution of Civil Engineers (address as above), 1978. Department of the Environment, Seymour House, Whiteleaf Road, Hemel Hempstead, Hertfordshire HP3 9DE.


Section 4 Institutional barriers E.C.Reed Northwood, Middlesex D.J.Hinton Anglian Water Authority, Cambridge and A.T.Chenhall Institutional Barriers

North of Scotland Hydro-Electric Board, Edinburgh Besides the undoubted economic and financial obstacles likely to face the developer of a small potential hydro-electric source in the United Kingdom, it is ( recognised that there are a number of legal and institutional barriers. In discussions with the National Association of Water Power Users (NAWPU), a paper produced by the Association for the Watt Committee working group Appendix 4) identified these legal and institutional barriers as ‘factors inhibiting development’. To some extent, recent legislation, in particular the Energy Act 1983 (which received the Royal Assent in June 1983) has altered the situation to such a degree that the working group believes that an examination of the new circumstances is justified. The amount of legislation that might apply to a hydro-power developer could be vast, depending upon the scale and intent of the development. Most of this alegislation, however, is common to anyone constructing a building or running a small enterprise. Examples would be the need to obtain planning permission (under the Town and Country Planning Acts in England, Wales and Scotland) or Building Warrant. If the scheme is to be run as a small business, legislation such as the Health and Safety at Work Act has to be considered. Since these matters are not specific to hydro-electric developers, and are at least moderately familiar, they are not considered further in this Report. Nevertheless, it should be remembered that they remain part of the overall picture and that they add to the general burden of legislative procedures with which any developer must comply. The remainder of this Section covers only those aspects of legislation that have particular relevance to small-scale hydro-electric developments, although some of it may also be of relevance to other electricity ‘autoproducers’. Since

INSTITUTIONAL BARRIERS 49

separate legislation and institutions obtain in Scotland, Northern Ireland, England and Wales, the significant differences applicable to each region are indicated. 4.1 Water 4.1.1 England and Wales The legislation that may face a small-scale hydro-power developer with regard to water could be considered to be formidable. The matters that are covered by legislation are: abstraction; pollution prevention; land drainage; impounding; and fisheries. Furthermore, there are ten Water Authorities that administer the application of the legislation in their respective areas in England and Wales. These authorities and various other bodies were consulted by the working group. (a) Abstraction The licensing of, and the charges for, the abstraction of water are certainly the most complex part of the water problem for small-scale water-power users, and it is worth noting that NAWPU was formed, among other things, to ease the constraints with regard to abstraction caused by the Water Resources Act 1963. Under Section 23(1) of that Act, no-one may abstract water from a source of supply except in pursuance of a licence. The 1963 Act gave powers of enforcement to the river authorities, and, as a result of differing interpretations among these authorities as to the licensability of use for power generation, representations were made to the Parliamentary Commissioner for Administration particularly in relation to charges arising from the licences. This led in 1 974 to the issue of a memorandum by the Department of the Environment and the Welsh Office entitled ‘Use of Water for Milling or Power Generation: Circumstances in which a Licence is Required’, which is included as an appendix to this Report (pages 53–55). The Water Authorities are entitled to levy a charge on the whole of the licensed abstraction in accordance with charging schemes made under Section 31 of the Water Act 1 973. All the Water Authorities, however, drew attention to new legislation which was introduced in the Energy Conservation Act 1981, and particularly to Section 16 which revises Section 60(2) of the Water Resources Act of 1963. Broadly speaking, the 1 981 Act refers to the need to conserve sources of energy and the desirability of preventing water charges from inhibiting the use of water as a source of energy. All Water Authorities were prepared to give consideration to this by allowing reduced charges in appropriate circumstances, but the discretionary nature of these powers has led to wide differences in interpretation, and a degree of uncertainty for the small hydro-power developer. (b) Pollution prevention


Most small-scale schemes for the discharge of water from a turbine would not be such as to be considered a trade effluent, and therefore a consent to discharge in accordance with the Rivers (Prevention of Pollution) Act 1951 may not be required. It would be necessary to establish this point with the relevant Water Authority. Under the Rivers (Prevention of Pollution) Act 1951, the definition of a trade effluent reads as follows: ‘Trade effluent includes any liquid (either with or without particles of matter in suspension therein) which is discharged from premises used for carrying on any trade other than surface water or domestic sewage’. (c) Land drainage Most hydro-electric schemes that are installed entail the construction of either under- or over-water courses. If these are constructed on ‘main’ rivers, consent would be required from the water authority in accordance with Section 28 of the Land Drainage Act 1976. If, on a ‘non-main’ river, the proposed construction causes an obstruction to flow, a similar consent is also required in accordance with Section 29 of the 1976 Act. (d) Impoundment If in a scheme there is to be impoundment of water, it is necessary under Section 36 of the Water Resources Act 1963 to apply for a licence to impound, in addition to any licence to abstract which may otherwise be required. In the event that the impoundment entails storage of more than 5000000 gallons of water above local ground level, in accordance with the Reservoirs (Safety Provisions) Act 1930, both the design and periodic inspection of the impounding structure would need to be carried out by qualified engineers as specified under that Act. New legislation under the Reservoirs Act 1975 is soon to be implemented and will strengthen certain sections of the old legislation. (e) Fisheries The Salmon and Freshwater Fisheries Act 1975 requires any scheme which interferes with river discharge by impoundment or by abstraction to have regard for the safety and passage of fish. Sections 12 to 15 of that Act refer to sluicegate operation gratings for protection of fish at intakes, discharge points and consents. It can be seen from the above that the legal/institutional requirements of the Water Authorities in England and Wales are very comprehensive and that some consultation with these authorities is required before proceeding with any smallscale power development. 4.1.2 Scotland and Northern Ireland Compared to the situation in England and Wales, the situation in Scotland and Northern Ireland appears relatively straightforward. The Pollution Prevention and Land Drainage legislation must be complied with as in England and Wales, but, where a landowner owns the water rights to a resource (generally by owning


the river or loch) and the salmon rights (which can in some instances be separately held), there are no special legal barriers to the use of that water for small hydro-electric development. In particular, there is no legislation that results in the levying of abstraction charges, which the NAWPU seem to regard as one of the most damaging elements in the current batch of legislative barriers to hydro-power development. There is, however, a common-law requirement that the developer should not alter the use of the water to the prejudice of users below him, which might in some circumstances affect the way in which the scheme was designed. Normally, however, the passing of water through a turbine, with its subsequent return to the water course within the developer’s own estate, would not be considered prejudicial to other use. The Reservoirs (Safety Provisions) Act 1930 applies as in England and Wales, as will the Reservoirs Act 1975, but the limit of 5000000 gallons is not likely to be breached by the majority of small hydro-electric developments. 4.2 Electricity 4.2.1 England and Wales With the passing of the Energy Act 1983, many of the obstacles to the private generation and sale of electricity have been removed. It has always been the case that anyone can generate electricity for his own private use, or as an activity subsidiary to his main business, but prior to the 1983 Act generation as a ‘main business’ was the preserve of the electricity supply industry (Section 23 of the Electric Lighting Act 1909). It was also possible for a private developer to arrange to generate in synchronism with mains supply, and to sell as well as buy electricity from the public supply network. The technical requirements for such interconnection were not, however, published, and tariffs were a matter for negotiation (with the balance of negotiating power lying with the public supply body). It was not permissible to transfer power from one location to another over the public supply network. The 1983 Act repeals or modifies those sections of the Electric Lighting Act 1909 and the Electricity (Supply) Act 1919 that restricted private supplies, and it creates new rules for potential small hydro-electric developers. The only restriction now placed upon such a developer is that, if he intends to build or extend a station with a capacity exceeding 10 MW, he must give the Area Electricity Board written notice of his proposals. (The form and notice required for such proposals has recently been published as Statutory Instrument 1 984 No 1 36.) Since the 10-MW limit is in excess of the range considered by the Watt Committee working group, this restriction is unlikely to be relevant.


In addition to removing restrictions on construction, the new Act places certain duties on Electricity Boards which will facilitate connection of small hydro-electric suppliers to the National Grid and allow the sale and purchase of power surplus to local requirements. Unless it is technically not feasible, the Electricity Boards must purchase surplus power and must permit the use of the public transmission and distribution network as a common carrier for the supply to any premises. In addition, the Boards must fix and publish tariffs for such transactions on principles laid out in the Act. These principles are that buy-back tariffs should not increase prices payable by the Board’s ordinary consumers, and that they should reflect the costs that would have been incurred by the Board but for the purchase of the privately generated power. A disputes procedure is also laid down and has been published as Statutory Instrument 1984 No 135. Thus, provided a private hydro-electric developer complies with Section 2 of the Energy Act 1 983 (which in practice he would almost certainly do by virtue of his capacity being less than 10 MW), no legal obstacles prevent his constructing the scheme. If he wishes to sell power and to use the public supply network, tariffs have now been published and the technical specifications likely to be required have been available for some time (Electricity Council Engineering Recommendations G47 and G26).* As for hydro-electric development by the Central Electricity Generating Board or any Electricity Board, these Boards would have to obtain consent for construction from the Secretary of State for Energy in compliance with either Section 2 of the Electric Lighting Act 1909 or Section 6 of the Electricity Act 1957. 4.2.2 Scotland By and large, the situation in Scotland is now similar, but not identical, to that in England and Wales. Until 1983, Section 35 of the Electricity (Scotland) Act 1979 required anyone desiring to build a hydro-electric scheme in excess of 50kW to obtain the consent of the Secretary of State for Scotland (which would in practice be given only after consultation with the Scottish Electricity Boards). The Energy Act 1983 amended this situation by replacing the 50 kW limit with one of 1MW. Thus, although the limit for a private developer in England and Wales is now for most practical purposes 10MW, in Scotland ministerial consent procedures have to be followed for a scheme over 1MW. Apart from this, the position for the private developer, at least relative to the sale of electricity and the use of the public supply network, is identical to that described for England and Wales. The two Scottish Electricity Boards, in the event that they wish to develop hydro-electric schemes, must obtain consent from the Secretary of State for Scotland under Section 10 of the Electricity (Scotland) Act 1979.


4.2.3 Northern Ireland In Northern Ireland, the relevant statutory instrument is the Electricity Supply (Northern Ireland) Order 1972, which establishes the Northern Ireland Electricity Service—a body similar in function to the two Scottish Electricity Boards, which both generate and distribute electricity. In most respects relating to private production of electricity, this piece of legislation is similar to that superseded in England, Wales and Scotland by the Energy Act 1 983. For example, Section 30 prohibits any person other than the NIES supplying electricity as his primary business, and Section 33 prohibits the construction of private generating stations without the consent of the Ministry unless regulations made by the Ministry are complied with. The order also contains regulations regarding the provision of stand-by supplies to private suppliers by the NIES. Overall, the position in Northern Ireland is much as it was in Scotland, England and Wales prior to the passing of the 1983 Act. The present administration has not, as yet, announced plans to pass parallel legislation to the 1983 Act for Northern Ireland, although it has been stated that the spirit of the 1983 Act will be adhered to by the NIES in its dealings with private producers. 4.2.4 Powers to acquire land and wayleaves It is perhaps worthwhile noting in passing that, whereas the various Electricity Acts confer wide powers upon the various public supply bodies to acquire land, acquire transmission and distribution wayleaves, dig up roads and enter premises (also to acquire water rights in Scotland), no such powers are available to private developers of small hydro-power schemes. By and large, this is very unlikely to present any obstacles, since the size of most schemes would dictate primarily local use of the power. It might in some circumstances (more probably in remote locations in Scotland or Wales) make it difficult for privately promoted small schemes to be developed to the full where local load was smaller than potential capacity. 4.3 Environmental Considerations Until the recent promotion of the Kielder Dam hydro-electric development (and subsequently the Drumjohn and Kinlochewe schemes in Scotland), there had been no significant hydro-power development since the early 1960s. As a * Recommendation G59 will replace Recommendations G26 and G47/1 from about March 1985.


consequence, much of the argument about the environmental impact of such schemes had been forgotten, to be replaced by the currently more popular themes (at least as far as power generation is concerned) of nuclear safety, acid rain and the storage of radioactive waste. In the U.K., therefore, hydro-power is often thought of as clean, renewable and environmentally benign—an attitude not shared by the environmental lobby, particularly in the numerous countries with more active hydro-power development programmes, such as Norway, Sweden, Canada and New Zealand. Environmental considerations enter the field of institutional barriers by way of either the Town and Country Planning Acts, the Energy Act or any of several of the various Electricity Acts. All of these acts contain clauses demanding that the developer of small hydro-power resources, whether private or public, submits the scheme to the appropriate national or local government department for approval. It is normal at this stage for the department concerned to open the application to objections by outside bodies or individuals, which can be on a variety of grounds including those generally described as environmental. Once objections have been received they are resolved if possible, and if not resolved they are generally submitted to some form of public inquiry before a final ruling on the scheme’s acceptability can be made. The time and effort required by a developer in going through the appropriate consents procedures is very variable. Consents for very small schemes obtained under the planning acts are unlikely to receive much attention other than locally, and may be issued within a matter of months. On the other hand, larger schemes may receive much wider attention, resulting in public inquiries, the whole consent procedure taking over a year and demanding much effort from proposers and objectors alike. Although grounds for objections to a particular development can range extremely widely, environmental objections are particularly important to hydroelectric developers. It is an unfortunate fact of life that the majority of terrain suitable for hydro-power projects is also terrain considered to be of high amenity value. This seems to apply almost universally to any large area of standing water or any stretch of running water, be it lowland or highland, and is doubly true when combined with mountainous, rugged or wilderness landscape. Such areas are therefore highly likely to be considered as scenic heritage and may support a large body of tourist interest (which in turn may affect the local economy). In addition, the terrain may support agricultural or forestry interests and may provide important land or water habitats for flora and fauna. A hydro-power project can affect such interests in many ways in both its constructional and operational phases. In the construction phase, the excavation and deposition of spoil and the storage of construction materials and equipment are likely to have a considerable impact. In both phases a number of the scheme’s components can cause such impact, including the dam or intake, the pressure pipeline if not buried, the power station building, the substation, the high-voltage connections if provided by overhead line, and most particularly the access roads. In addition, in


the operational phase, effects on the water level of the upper (and lower) reservoirs may expose silt margins, and the watercourse between intake and power station (which is likely to include waterfalls in areas with favourable terrain) may lose much water. Typical small hydro-power terrain can also support a wide range of recreational activity besides tourism. Thus climbers, hill walkers, bird watchers, naturalists, fishermen, canoeists, dinghy sailors and hunters may all have an interest in the area to be developed, and are all likely to see various aspects of the scheme as affecting their interests. Some features, such as access roads, may be considered an advantage by some groups and an abomination by others. Features such as overhead lines or pressure pipelines are likely to be universally considered bad. The most serious objections are likely to be those affecting the natural habitats of flora or fauna, such as trout and salmon spawning reaches, or interference with deer movements or nesting areas. Less serious may be objections concerning interference with access, such as footpaths, which can usually be accommodated without too much difficulty. In some cases, the recreational impacts may also have a significant effect upon the local economy where the activity supports hotels or specialist shops or other local employment. In addition, the scheme may interact with the interests of local forestry or agriculture. 4.4 Conclusions and Recommendations Preliminary investigations into the existence of institutional barriers to smallscale hydro-power development led the working group to the conclusion that Parliamentary legislation had placed on the Water Authorities in England and Wales a number of statutory requirements that were complicated to administer. However, the fact that there are fewer inhibiting factors in Scotland and that the Scottish terrain lends itself more to development of hydro-power does not seem to have brought about a surge in the utilisation of small-scale hydro-power. During the proceedings of the Consultative Council Meeting* held at the City Conference Centre, London, on 5 June 1984, it became clear that these statutory requirements were of themselves an impediment to progress for the small developer. Furthermore, the administration of the legislation was in certain cases difficult to interpret and therefore, also, an impediment to progress. An example of the problems of interpretation arose at the meeting when the diagrams in the memorandum by the Department of Environment and Welsh Office entitled ‘Use of Water for Milling or Power Generation: Circumstances in which a licence is required’ (reproduced here as Appendix 3 on pages 53–55) were projected. The resulting discussion revealed that the learned audience held markedly conflicting views on the interpretation of these diagrams—which had been intended to improve the understanding of the problem.


Major developers have the resources to surmount the problems caused by the statutory legislation, but the working group has concluded that the individual developer or small business is concerned at the impediment to progress that is created by the legislation and its administration. The Energy Act 1983 has significantly altered the position with respect to small hydro-electric development; new statutory rights to the use of the grid system and to the sale of surplus power tend to a further reduction of the risk of investment in small schemes by providing a guaranteed outlet at a predetermined price. The small developer with limited resources requires a simple solution from the Water Authorities to make the promotion of his scheme viable. It is understood that one Water Authority has instituted a flat charge for abstraction and that this arrangement has caused no problems. We recommend that consideration be given by all Water Authorities, in conjunction with other interested parties, to the identification of a simple list of principles that are required to be observed by the user. Bearing in mind the limited influence that small-scale hydro-power use would have on the Water Authorities’ operations, the payment of a reasonable set fee should prove workable.

* See Appendix 1. page 51.


Section 5 Economics of small public and private schemes A.T.Chenhall North of Scotland Hydro-Electric Board, Edinburgh and R.W.Horner Stoke Poges, Buckinghamshire

Economics of small public and private schemes

5.1 Introduction The central question that faced the Watt Committee working group from its inception was quite simple: why is small hydro-power potential not being fully exploited in the United Kingdom? Other papers in this Report examine four aspects of that problem: (a) the potential; (b) legal, statutory and other barriers to development; (c) civil engineering aspects; and (d) the availability of suitable plant. Before an answer to the question can be attempted, it is necessary to consider economics, finance and risk. It may be worthwhile to consider, first, the other side of the question explicitly. Why develop the potential at all? Why not leave the weirs and waterfalls as pleasant visual attributes of our landscape? After all, they are not (nationally speaking) a very significant resource. The whole U.K. hydro-power potential could be replaced by a single full-size nuclear- or coal-fired power station. The first answer is that the fuel is free and potentially everlasting. The popular image of hydro-electric power is that once the hurdle of finding the money and building a scheme has been overcome, the consumer can enjoy virtually free electricity for a very, very long period indeed. This may not be as close to reality as some people might like, but it does embody the essence of why hydroelectricity is seen as worthwhile. In addition, of course, in pollution-conscious times the relatively benign nature of the environmental impact of small hydro-power is seen as a very positive advantage, and it undoubtedly accounts for some of the support that small hydropower attracts. By the same token, it also tends to attract support from those who


Figure 5.1 Typical arrangement of scheme with high-level catchment.

believe in individual and consequently small enterprise rather than the provision of services by national or multi-national organisations. With these answers in mind, the economic picture for small hydro-power is considered here in more detail under three headings: costs, benefits and economics. 5.2 Costs The capital cost of building a small hydro-electric scheme can be conveniently broken down into four broad categories: (a) weir or dam and intake; (b) pressure tunnel, pipeline, headrace or penstock; (c) power station and other civil works (building, tailrace, access roads etc.); (d) mechanical and electrical plant. The costs are broken down in this way to clarify a simple point: with most generating or power-producing plant, the capital cost is related, often almost linearly, to size or capacity. This means that over a wide range of different types of prime mover the capital costs can be typified as, say, so many pounds sterling per installed kilowatt (or horsepower). For example, the Central Electricity Generating Board recently published figures of £664/kW for coal-fired power stations and £1033/ kW for a nuclear power station. For hydro-electric power these generalisations

ECONOMICS OF SMALL SCHEMES 59

are not even approximately true, because the topography, geology and hydrology of the individual site predominate among the costs. This can be illustrated by going through the four categories above, noting the design process and the influence of site-specific variables. 5.2.1 Weir/dam/intake costs The first essential in any scheme is to provide a basic intake point for water at some point above the potential site for the turbines. Consider, first, the situation of a high-level catchment on, say, a Scottish or Welsh mountain, such as that shown in Figure 5.1. It is a relatively straightforward matter, given a relief map of the area and a rainfall map, to work out the potential water run-off from such a site. There are, of course, complications due to the permeability of the rock, the type of vegetation over the catchment and the surface characteristics of the area. So, first, where should the intake be placed? If it is placed low down the catchment, the catchment area is increased and water capture is maximised; if it is higher, that capture is reduced but the head available to drive the turbines is increased. The output of the scheme is obviously a function of the volume of water captured, but the energy available from any given volume is also a function of the head. There is thus a quantifiable trade-off between the two which is primarily influenced by the catchment topography and hydrology. In addition, suitable geological conditions must be found if the intake is to include a sizable weir or dam; the site must permit the catchment to be blocked without extending too far on either side. Next, the height of the weir or dam must be decided. It must be remembered that rainfall is an intermittent event, and that run-off will not be a constant from day to day or season to season. If a hydro turbine is large enough to take the highest flows, it will operate inefficiently on the lower flows during the major part of the year. If the turbine is smaller, it will not be able to cope with high flows, which will have to be spilled and lost. One solution is to store the high flows and release them at low run-off times by building a high weir or dam. The bigger the weir, and greater the storage, the smaller the turbine that must be installed and the more of the potential run-off can be captured. The amount of storage for each 1m of the height of the dam is a function of the catchment topography, and the whole equation depends upon how ‘flashy’ the run-off is. The situation that might occur on a lowland river in England is very similar. Once again, water flow is unlikely to be constant throughout the year, and site conditions will decide for any required capture of water how much must be spent on weir and intake, how deep the foundations need to be, what materials can be used and how high and wide the dam needs to be. A complication is that most suitable sites in England and Wales have probably been developed at some time in the past. There may well be existing weirs and races, built from a variety of materials, for use by pre-existing water-mills of many types. The cost of


Figure 5.2 Typical designs of hydro-electric power units with approximately 2 MW output.

development may therefore include the possibility of refurbishing or utilising directly existing facilities.


5.2.2 Pressure tunnel, pipeline or headrace The next stage of the design is to connect the intake to the turbines in the power station. For any given volume of water collected at the intake, the maximum amount of energy is extracted by increasing the head—the height difference between intake and turbine—as far as possible. Unfortunately, for this purpose the length of the connecting pipe must be increased, which is often very expensive. There is a trade-off between increasing output and increasing cost, which is primarily affected by the slope or gradient between intake and power station. High gradients generate greater heads for a given length and favour longer pipelines, whereas low gradients dictate shorter ones. Allied to the question of length is that of the diameter of the pipe. As pipeline diameter increases, so does cost; but for any given diameter, length and head, there is a maximum possible flow and a frictional loss in head available at the turbines. The frictional losses in the pipe increase dramatically as this flow is approached. Once again, there is a trade-off which is a function of length and head and thus of gradient. Finally, whether tunnelling is feasible or not, whether or not the pipeline can be buried and which materials are suitable for a given situation will also depend upon geological, topographical and environmental factors. 5.2.3 Mechanical and electrical plant Having decided on the intake and connecting pipeline, the influence of site conditions on the choice of plant must be considered. Much of this ground is covered in the Section of this Report that deals with mechanical and electrical plant. The principal determining factor is the head (and hence the gradient of the site). At very high heads, impulse turbines of the Pelton or Turgo type are favoured. At lower heads, reaction turbines of the Francis type are suitable, and at very low heads bulb, tube or Kaplan turbines. Each has different characteristics in terms of size, simplicity, robustness, abrasion resistance, controllability and efficiency over a range of flows. Catchment characteristics such as head, flow variability and solids in suspension all influence the choice of the turbine plant, and hence the cost for a given power output. By and large, the relationship between installed capacity and cost is fairly linear for the electrical equipment, but as sets approach the micro sizes the cost relationship becomes distorted by the fixed costs associated with the equipment that is needed to comply with connections to the National Grid.


Figure 5.3 Capital cost distribution of hydro-electric schemes in Scotland.

5.2.4 Power station and other civil works The last design question is the cost of the power station building itself, together with such things as tailraces, screens and access roads.


The cost of the power station depends primarily on size, and thus upon turbine type and upon head. As head increases, the power output for any given physical size of turbine increases, so the power station building can be proportionately smaller per kilowatt of output. Similarly, different turbine types demand different physical layouts and thus different costs (see Figure 5.2). It goes almost without saying that the provision of such items as access arrangements and electrical conductors to points of demand are themselves site-dependent. Remote locations with little local demand will necessarily be more expensive to reach and to carry power away from. 5.2.5 Other site-specific considerations The site conditions are thoroughly inter-related with the engineering design and capital cost; but there are other site factors which could also affect the final cost. For example, are compensation flows needed from the dam to irrigate the old watercourse for environmental reasons? Are there other water interests between the intake and discharge sites? Will the pipeline have to be buried or must the power station be built in a special way to meet environmental legislation? These and other matters all affect the capital-cost/output equation. 5.2.6 Typical costs It has been shown above that it is difficult to generalise about the costs of hydroelectric installations and that it is misleading to talk in terms of pounds sterling per installed kilowatt, since the design and catchment characteristics of the scheme determine how many kilowatt-hours are generated by each 1kW of installed capacity. For example, a study of 65 schemes in Scotland shows average costs of about £1200/kW installed, or, more meaningfully, 31 pence per annual kWhr (Figure 5.3). The costs range from £700 to £2000/kW and from 16 to 70 pence per annual kWhr. These were all ‘green-field’ schemes, and no doubt wider ranges are possible where some of the civil works pre-exist, as at old mill sites. Francis, in his paper on low-head and run-of-river schemes,6 quotes cost ranges of from £300/kW to £1500/kW installed (at 1978 levels), which is broadly in line with the Scottish findings, given inflation between the two dates. Figure 5.4 shows the percentage cost breakdown for two real schemes of identical installed capacity, illustrating the differences in annual output, capital cost and cost breakdown which result from differing site conditions.


Figure 5.4 Breakdown of capital costs of two hydro-electric schemes with identical installed capacities.

5.2.7 Oncosts The question of the costs of designing, engineering, managing and obtaining consents for the project must be briefly considered. These costs may be viewed differently, depending upon whether a private individual is constructing the project or the developer is a firm or nationalised body. To the private individual the provision of these services may well be something that he undertakes himself


and is not charged to the project financially. The time and effort involved may be considered a free resource, although the obstacles met in acquiring the knowledge or skills required, and particularly in overcoming the consents problems, are often cited as tangible reasons that prevent more widespread hydropower development. To a private firm or nationalised body these aspects are not cost-free, and may involve not only ‘in house’ resources but the use of specialist consultants. For larger schemes these costs may account for from 10 to 30% of the total capital cost, but as the size of the scheme diminishes the proportion may increase, since the basic design effort remains the same regardless of size. This is at least one reason why firms and nationalised industries see a lower size limit to economically viable schemes. The consents procedures also bear upon different developers in different ways. To a private developer the acquisition of planning permission and water licences may be his main concerns, possibly combined with the procedure for obtaining consent to run in parallel with the public electricity supply network. For larger schemes it may also be necessary to obtain wayleaves or other consents. Nationalised bodies, on the other hand, will be more concerned with obtaining statutory consent to build the scheme and acquiring transmission wayleaves. These procedures, together with the generally larger impact of such schemes, may also lead to public inquiries—a very time-consuming and cost-raising activity. Such bodies have access to extensive powers for the acquisition of land rights and wayleaves which are not available to private firms or individuals. The nature of the developing body, and thus the treatment of these costs, has a fairly significant impact upon the perceived viability of any individual scheme. 5.2.8 Running costs Once the hydro-power plant has been designed and constructed, the annual running costs must be considered to obtain a true picture of the overall cost of power production. Again, the situation is dependent upon the size of the scheme and the type of developer. By and large, the routine running and maintenance costs for small hydro-electric schemes are very low. With careful design, schemes can be built to operate virtually automatically for long periods and to require very little in the way of annual maintenance. At the limit, attendance once per week or so for the cleaning of screens and filters may be all that is required. For the private individual these activities, like the oncosts, may be considered a zero cost resource and not figure in the economic equation at all. Firms and nationalised bodies, concerned with larger schemes, will have to set aside resources to ensure the safety, integrity and smooth operation of the plant. As schemes decrease in size, these costs become relatively larger per unit output


until they contribute to making even the most promising of very small schemes uneconomic. At the very low end of the small hydro-power scale, say under a few tens of kilowatts, the fixed costs of Water Authority abstraction charges and Local Authority rates become particularly important. These charges are one frequently cited reason for the non-development of small resources by private individuals. The Water Authority abstraction charges are (perhaps justifiably) seen by the small developer as unfair, bearing in mind that the water is not diminished in quantity or quality on return to the river course a little further downstream. 5.2.9 Electricity Board regulations The final aspect of costs to be considered here is compliance with Electricity Board regulations. Because runoff into hydro-electric schemes varies from day to day and season to season, it is very rare to find total correspondence between output and local efectricity demand. Thus, at sizes above a kilowatt or two, the average developer finds himself forced to consider either foregoing production or finding some other outlet for his surplus. This surplus may occur at certain times (most likely at night) despite the fact that he still remains a net importer of electricity from a public supply network (Figure 5.5). The most obvious course of action from the developer’s point of view is, then, to run his generator in parallel with the public supply network, and import or export as water conditions dictate. Two problems immediately arise: first, that of buyback tariffs, and, second, that of technical compliance with engineering standards, particularly those for protection. Not unreasonably, the Electricity Boards demand compliance with certain standards, particularly for protection, to safeguard their own plant and, more importantly, the lives of their staff who work on the system (see Electricity Council Engineering Recommendations G47/1 and G26). The problems for the private producer are twofold. First, he must have the expertise, or must buy the expertise, to design the protection installation, and, second, he must, of course, purchase and install a fairly sophisticated set of protection equipment. The cost of doing so may be out of all proportion to the benefits to be gained by interconnection unless significant exports of power are expected. It is to be hoped that wider application of parallel generation (by say micro-CHP units) will result in packaged and standardised protection equipment whose cost will be appropriate to small-scale hydro-power producers, and that future updates to the regulations will simplify the situation. Recommendation G59, to be published about March 1985, is such a simplification of Recommendations G47/1 and G26.


5.2.10 Importance of fixed costs Given the broad range of costs, it is fairly obvious that some schemes are going to be worthwhile and others not. The roles of fixed costs, such as operation and maintenance, design and engineering, Electricity Board and Water Authority charges, have been highlighted, in that they often set lower limits to the size of viable schemes; a figure of 40 kW has been quoted as the lower limit for connection to the National Grid. 5.3 Benefits It follows that the next question is that of the benefits from a hydro-electric scheme, what are they worth, and at what cost are such schemes economic. The direct and indirect financial benefits from the operation of small hydropower schemes in the U.K. derive predominantly from the supply of motive power, which is almost (although not quite) invariably transformed into electricity before use. A secondary benefit, particularly in parts of Scotland, is that of flood control; a well operated storage scheme can go a long way towards regulating flood flows and containing potentially damaging volumes of run-off. In passing, it should be mentioned that in countries other than the U.K. substantial benefits may arise from other water-related aspects. The provision of potable water supplies, the irrigation of crops and the provision of areas of water for recreational interests, such as fishing or sailing, are all seen as significant sources of benefit. Since in the U.K. (at least for small schemes) these aspects are not usually important, they are not considered further here. The same is true of the flood-control aspects, since direct payments are seldom attributable to this service. There are a number of options for the direct use of mechanical power from water turbines, including the drive to heat pumps, where the power characteristics and heat-source availability are particularly attractive. Nevertheless, the predominant option is the supply of power for electricity, and once again this is considered here under separate headings for private individuals and for Electricity Boards. 5.3.1 Private individuals and firms To the private developer of a small hydro-electric scheme, the principal attraction will be the replacement of units of electricity that he would otherwise have to purchase from the public supply network. Since the tariff for units supplied on this network includes both the capital cost of plant on the public network and the running costs of the predominantly thermal plant, it is relatively


Figure 5.5 Shortfall and surplus power generated by an independent scheme.

high—typically well in excess of 4p per unit for domestic consumers during daylight hours. Problems begin to arise if the output of the scheme does not match the developer’s demand for power at all times. He then has one of three main choices.


First, he could choose to dump units at times when his demand is less than production, to do without power when his output was less than his demand, and operate in isolation from public supply. By spending more on water storage and plant control he may be able to tailor his output to match his needs more closely, but this will involve greater capital cost. If he designs his plant to match his highest demands, he is likely to spill water for a great deal of the time, and if he designs for average conditions he is likely to be short of power at inconvenient moments. Second, he could operate in parallel with the public supply, importing at times of high demand/low output and exporting at times of low demand/high output. This will simplify his control arrangements and need for water storage, and satisfy his demand at all times. On the debit side, he will have to install additional protective gear and meet Electricity Board engineering standards. Perhaps more importantly, he will find that the tariff situation has changed. The units that he takes from the Electricity Board will cost him more, since the Boards have to recover their fixed costs of supply from a smaller number of units sold, and the units he sells to the Board will be valued at less than the units he buys, since the only avoided cost (to the Electricity Board) is the cost of fuel needed to produce those units at a large power station. The final main option is that of split-system running, where part of the developer’s load is met by the public network and part by the hydro-electric installation on a completely separate circuit. In this way it may be possible to match demand to output (using storage radiators or water heaters to soak up surplus output and avoid too much spillage) whilst maintaining public supplies for essential services at times of low output. The main problems here are the cost of having two entirely separate electrical networks and the inconvenience of having to juggle appliances from system to system in order to maximise utilisation of the scheme. 5.3.2 Electricity Boards By the public Electricity Generating Boards the benefits are seen slightly differently. Since they have a statutory obligation to supply electricity of a given quality (frequency and voltage) wherever and whenever it is demanded, they are interested not only in the units supplied by the small hydro-electric scheme but also in whether or not those units will be available at times of peak demand. If the units will not be available at times of peak demand, and demand must Table 5.1 Megawatt-size scheme: development by private company or Electricity Board Private company Electricity Board Capacity, MW sent out

8.5

8.5


Private company Electricity Board Output, GWh/annum Capital cost, £×106 Capital charge at 5% TDR over 30 years, £×106 per annum Financial cost at 10% interest rate over 10 years, £×106 per annum Depreciation charge, £×106 per annum Cost of operation and maintenance, £×106 per annum Perceived total cost of scheme, £×106 per annum Cumulative benefit over 30 years, at displaced thermal cost (at 2p per unit), £×106 Cumulative benefit per annum at tariff rate (at 3. 5p per unit), £×106 Cumulative NPV, £×106 PP, years IRR, % Verdict

21.7 4.68 N/A

21.7 4.68 0.30

0.47

–

0.24 0.03

– 0.03

0.79 –

0.33 6.67

0.76

–

0.0 6 10 Not worthwhile

1.60 – 7.6 Viable

NA, not applicable. Table 5.2 Micro scheme: development by private individual or Electricity Board Private individual Electricity Board Capacity, kW Output, kWh Cost—Equipment, £ —Engineering and design, £ Total, £ Financial cost (30 years, 5%), £ per annum Financial cost (10 years, 10%), £ per annum Operating cost: Materials, £ per annum Labour, £ per annum Total costs, £ per annum Benefits at 2p per unit, £ per annum Benefits at 4p per unit, £ per annum Cumulative NPV over 30 years, £ Cumulative NPV over 10 years (5% inflation), £ Verdict

10 44000 9000 0 9000 – 1465 200 0 1665 – 1760 – 12046 Profitable

10 44000 9000 1000 10000 650 – 200 300 1150 880 – 5841 – Uneconomic

still be met, one of three measures must be adopted: (a) other plant with firmer resources (coal, oil or nuclear plant) must be installed as well, or (b) more


storage will have to be added to the hydro-electric scheme (if possible) to ensure that it will have water at peak times, or (c) more hydro turbines will have to be installed to achieve a probability that at least one will be available. A plant whose output is always available at time of system peak is termed ‘firm’, whereas one whose output may not be available is termed ‘non-firm’. Firm output is worth more than non-firm output, since non-firm output must be backed up by additional firm capacity. The difference in value is sometimes known as the ‘firm capacity credit’. Hydro-electric schemes in general in the U.K., and particularly small schemes which typically include very little storage, are generally non-firm. The value of their output is therefore considered to be the value of the coal, oil or nuclear fuel that would otherwise be used to produce that same output at conventional thermal stations, together with an allowance for other marginal output-related costs (such as some maintenance and fuel-handling charges) at thermal stations. Compared to an individual who evaluates the scheme’s benefits against current domestic or industrial tariffs, an Electricity Board is likely to value such units at only about half of the tariff rate as the portion attributable to marginal thermal running costs. 5.4 Economics From the foregoing discussion of costs and benefits, it is apparent not only that costs are site-specific, but that some elements will be treated differently, depending upon whether the potential developer is a private individual, a private firm, or a nationalised Electricity Board. It is also apparent that the same is true of the treatment of benefits. Put at its very simplest, an economic assessment is the process of balancing costs against benefits, and measuring the result against some standard to decide whether or not a venture is worthwhile. As the treatment of costs and benefits differs depending upon the body involved, it is predictable that the standard or yardstick for the balance also varies from body to body. Economic results can be expressed in many different ways. Net present value, internal rate of return, payback period and cost-benefit ratio are just four of the ways in which the same numbers can be presented in the search for an index of worth for a project. In all of these, two factors are explicitly or implicitly important: first, the length of time during which a project is or remains remunerative, and, second, the developer’s ‘time preference for money’ expressed as a discount rate or as a desired internal rate of return (IRR) or payback period (PP). Both vary significantly between private and public developers, and from body to body and project to project within those categories. One of the reasons for these variations is the ‘riskiness’ of a venture.


5.4.1 Private bodies Private bodies vary substantially from individual to individual in their methods of economic assessment, although a great many appear to put emphasis on PP as the prime economic yardstick. The biggest distinction within this group is often between individual householders or landowners, who may be interested in small hydro-power for other than purely financial reasons, and who may take a fairly long view of asset lives and PP, and other organisations interested in small hydropower as a commercial proposition. In the latter case it is not unusual to find short PP (3–6 years) and high IRR (20–30%) used as yardsticks for prospective schemes. 5.4.2 Public bodies Public bodies, by comparison, are relatively well regulated and hence uniform. For the Electricity Boards the framework for economic assessment is laid down in a Government white paper entitled ‘The Nationalised Industries’ (Command 7131).17 This states that the Boards must use methods that ensure an overall real rate of return of 5%. This, then, is the basic rate used for the majority of economic assessments, although higher rates may be considered appropriate for projects that might be considered ‘risky’ or ‘optional’ (in the sense that they are not strictly necessary to maintain safe and secure supplies of electricity to consumers, although they may contribute to cheaper or more economical supplies). As far as length of life is concerned, the nationalised industries are concerned with supplying services to the public over long periods as cheaply as possible. They therefore take a long-term view when assessing a scheme, and commonly consider lives for hydro-electric schemes in excess of 20 years. A typical figure for many installations would be 30 years, with some elements (dams for example) being amortised over periods up to 60 years. Methods of assessment vary a little, but in the majority the principle of the discounted NPV of the cost and income streams is by far the most important, although IRR and PP are also used. The minimum criterion is often a positive NPV at a 5% test discount rate (TDR) over (say) a 30-year life. 5.4.3 Examples The variations in the treatment of costs and method of assessment may lead to identical schemes being accepted or rejected, depending upon the body that does the assessment. Tables 5.1 and 5.2 illustrate this by showing typical values for a megawatt-size scheme (Table 5.1) and kilowatt-size scheme (Table 5.2) as they


might be assessed by various private or public bodies. In both cases the scheme design and cost are identical. Table 5.1 shows how the use of high discount rates or short PP can prejudice the economic outcome, and Table 5.2 illustrates how the treatment of some cost elements and a differing perspective on prospective benefits can affect the calculation. 5.4.4 Finance Related to the question of economics is that of finance. Obviously, if a potential developer has his own internal sources of funding, his methods of economic assessment and financial management need satisfy only himself. In many cases, however, capital must be borrowed from outside sources, and the developer has to consider real interest rates (as opposed to economic discount rates), cash flows, grants and financial limits. Such matters are once again highly specific to each individual case, and are likely to change over time. Interest rates may be fixed or variable, and have to be considered in relation to the current inflation rates. Cash flows have to take account of future inflation in the electricity tariff or alternative fuels. Grants or reliefs may be available to some projects for some individuals but not others. Even assuming that all these criteria can be met, capital may be rationed so that projects cannot be undertaken. 5.4.5 Risk Risk has already been mentioned briefly in the economics section of this Report as one of the factors that affect a developer’s economic criteria for passing or failing a particular project. Risk in a hydro-electric development appears in many ways. Will the resource (run-off, river flow) be as big as estimated, and will it be unaffected by influences outside the developer’s control (afforestation, diversion upstream etc.)? Can the resource be developed without cost over-runs, and will the completed scheme perform to expectations with regard to efficiency and availability? Will the benefits (electricity tariffs, alternative fuels) maintain their current real price over future years? One of the ways of dealing with risk is to increase the economic yardstick (increase the TDR or IRR, decrease the payback period) to a level where the risk is felt to be reasonable (and the rewards for success high enough) for projects which meet the yardstick. This method is frequently used by private firms and individuals, and goes some way to explain the high rates of return and short PP demanded. A more sophisticated means of assessing the problem is to attempt to define probability bands for each of the risk-bearing elements and to perform sensitivity studies of the economic results given the probabilities of the events concerned. These methods are more likely to be used by large organisations and nationalised


bodies and are used in conjunction with the basic (or central case) economic results in deciding whether or not to develop a resource. 5.5 Conclusions This Section of the Report began by asking why small hydro-electric potential is not being exploited more widely. In the past, nearly all the suitable sites for water-power extraction in England, and many in Wales, have been exploited. Today few are used. In 1 947 there were 27 small hydro-electric installations that provided public supplies of electricity. Seventeen of these in England and Wales are now (it is thought) closed. Undoubtedly one of the reasons for this state of affairs has been the rise in the ready availability and relative cheapness of alternative forms of energy from coal, oil or nuclear sources. The steady rise in the burden of capital costs, particularly those with a large civil cost element, together with the falling real cost of coal and later oil/nuclear power, has swung the economic balance away from hydro-electric power. Relatively recent sharp upswings in the price of all these alternative fuels have not yet produced the expected swing in the opposite direction. In conclusion, the issues raised in the Section of this Report that deals with cost and economics are now examined, highlighting those points (in no particular order) that contribute to the lack of momentum in small hydro-power development, and thus indicating where improvement in the situation is realistically possible. 5.5.1 Water Authorities The plethora of regulations relating to water supply, particularly in England and Wales, is referred to in a different Section of this Report. These regulations in themselves can be considered an obstacle to development. The principal among them are the need (again only in England and Wales) to obtain a licence for abstraction and the levying of abstraction charges. Many potential developers cite these as two of the most important of the numerous small obstacles to development, particularly since hydro-power development may not interfere with Water Authority objectives, and such charges are not made elsewhere. On the other hand, it must be stated that many authorities either overlook the charges or make minimal charges to domestic water-power developers, and that the authorities are obliged to protect the interests of the general public in the matter of water supply. It may also be noteworthy that in Scotland (where no such abstraction charges are made) there does not appear to be a markedly greater level of small hydro-power development.


5.5.2 Electricity authority In the Section on institutional barriers, and in the previous pages, reference is made to the situation where a developer wishes to run his scheme in parallel with the public supply network. Two issues are important here: first, the need to comply with certain standards, principally those concerning protection; and, second, the situation regarding ‘buyback’ and ‘standby’ tariffs. Until 1983 it was undoubtedly the case that the low buyback tariffs and lack of interest generally by the Electricity Boards in promoting autoproducers were obstacles to development. The Energy Act 1983 sought to redress that balance by giving autoproducers certain rights and laying out principles for autoproducer buyback tariffs. These regulations have been in force for a relatively short time, and it is probably too early to assess their likely impact. Whilst they are obviously a move in the correct conceptual direction as far as small hydro-power developers are concerned, it remains to be seen whether or not the practical upshot will satisfy all parties concerned. There are already signs that the new tariffs may not go far enough to satisfy autoproducers. With regard to engineering standards, the logic behind such standards is irrefutable, the main complaint being that the standard was perhaps too high or over-engineered. It may be hoped that the publication and widespread dissemination of the standards, together with their revision, will encourage the development of simple low-cost, mass-produced equipment, ‘type approved’, to meet them. Such developments will benefit autoproducers of all types, and go some way to assisting the development of small hydro-power schemes. 5.5.3 Grants and aids In order to exploit the U.K.’s small hydro-power potential, a large number of individuals (potential developers) will have to be convinced of its worth and then go on to take the decisions necessary to carry the project through. The disparities between the cost, benefit and economic assessment criteria used by differing individuals and bodies in assessing any one scheme have been noted above. One of the ways in which the national Government or the European Community (EEC) can encourage development along these lines is through the funding of grants or other forms of aid. Unfortunately, small hydro-power has found itself rather uncomfortably between two extremes when it comes to attracting such aid. In many ways it is considered a ‘mature’ technology, which means that it receives very little in the way of research funding. It also often fails to pass the ‘novelty’ criterion when it comes to demonstration projects. Furthermore, being capital-intensive, it often fails to pass the stringent economic criteria demanded of development and demonstration projects, which are often


expressed as payback periods and thus fail to get to grips with the longevity of hydro-power installations. 5.5.4 Design and engineering One of the fundamental conflicts of small hydro-power is that by definition (the individual resources being small) very little money is available in any one scheme for design and engineering. Nevertheless, as is emphasised in the Section of this Report that deals with costs, each scheme is different and in a perfect world demands full attention to the optimum selection of all the various criteria. The solution may be the application of the appropriate technology in each particular case. Two points arise from this. First, how does the small hydropower developer obtain advice on the ‘appropriate’ technology for his particular project? For those unable or unwilling to do their own research options are by and large restricted to the established engineering consultancies, or possibly a university-based consultancy service of the type recently set up at Salford. As yet the volume of work on small schemes does not appear to be sufficient to support specialised services appropriate to the smallest of schemes, although there are moves in this general direction. The second point is that the ultimate success of any programme of small hydro-power development must depend upon the availability of standard massproduced packaged equipment of low cost and high reliability with a minimum of operating and interfacing requirements. To some extent the development of such equipment depends upon the presence of a vigorous market, and hence the familiar ‘chicken and egg’ syndrome may occur. Encouragement may be drawn from the moves in this direction in the field of small schemes for combined heat and power (CHP) (somewhat accelerated by the Energy Act 1983) together with the undoubted market potential in the less developed countries of the world. Areas of particular note are the gathering momentum of micro-electronics in the fields of protection and control, which could simultaneously lower costs and raise efficiency, and the recent use of low-cost pumps in reverse as highly costeffective hydro turbines. Bibliography 1. 2. 3. 4.

Small Scale Hydro-Electric Power. ETSU, Harwell, November 1982. Vernon, K.R. Potential for Small Scale and Other Hydro developments. ESRC Paper, March 1981. Scott, M.M. Small Scale Hydro Power in the British Isles. Imperial College of Science and Technology MSC Report, September 1982. Birkett, D.G. Review of Potential Hydro-Electric development in the Scottish Highlands. Electronics and Power Vol. 25, No. 5, May 1979.


5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

Head, C.R. The Real Costs of Mini Hydro in Developing Countries. Modern Power Systems, February 1983. Francis, E.E. An Appraisal of Low Head and Run-of-River Water Power in England and Wales. Department of Energy, November 1978. Banks D. Imaginary Hydro-Electric Schemes, Paper presented to West of Scotland section of the Institution of Civil Engineers. Electricity in Scotland: Report of the Committee on Generation and Distribution in Scotland. HMSO, Cmnd 1859, London, November 1962 (the ‘Mackenzie Report’). Manser, W.A.P. Hydro Electricity in Scotland. Federation of Civil Engineering Contractors Study, 1984. Garcke. Manual of Electrical Undertaking. Vol. 44 (1946–47 edition). Crichton, C. Thirty years’ experience of private hydro-electric generation. Energy for Rural or Island Communities, Pergamon Press, Oxford, 1981. Agnew, P.W. Appropriate Control Systems for Water Turbines. Ibid. Johnson, F.G. Hydro power in the UK—past performance and potential for future developments. IEE Hydro Power Colloquium, May 1984. Prescott, W. Mini hydro plant—the packaged concept. Ibid. Williams, D. Turbine selection. Ibid. Grant, A. A pump as a small turbine. Ibid. The Nationalised Industries. White Paper. Cmd. 7131, HMSO, London, 1978. Proof of Evidence to the Sizewell Inquiry, Central Electricity Generating Board, London, 1984.


Section 6 Conclusions and recommendations J.V.Corney Sir Alexander Gibb & Partners, Earley, Reading and H.W.Baker James Williamson & Partners, Glasgow Conclusions and Recommendations

6.1 The Potential The working group considers that small-scale hydro-power is a valuable renewable source of power which is still unexploited and that the potential of small-scale hydro-power which could be economically developed at the present time as a useful addition to the energy resources of the United Kingdom amounts to somewhere between 500 and 1000 GWh/year (broadly between 200×103 and 300×103 t coal equivalent). 6.2 Obstacles The main obstacles which may have inhibited development in the past are considered to be: (a) The cost of electricity from the National Grid has been, until recent years, low enough to make small-scale hydro-electric development appear unattractive, particularly by comparison with the convenience of an easily available and reliable public source of supply. (b) Electricity authorities have shown little interest in small-scale developments. (c) Incentives for water authorities to explore and develop hydro-electric potential have been limited. (d) Prior to 1983, no positive action had resulted from Government discussions with the electricity supply industry and water authorities aimed at

CONCLUSIONS AND RECOMMENDATIONS 79

improving the situation (e.g. tariff arrangements) that had been brought out in Government-commissioned studies. (e) Owners had often not appreciated that they had an economic exploitable potential. There was no organised system of making owners and potential developers aware of their resource. (f) Financial backers have shown little interest in longer payback periods, even though these were demonstrably attractive in the longer term. (g) The grants system operated by the Government and by the European Economic Community is designed to assist innovative development but does not apply to conventional small-scale hydro-power development, (h) The obstacles to a developer in the shape of complicated statutory requirements, especially in England and Wales, are formidable, and the administration of legislation is difficult to interpret. (i) The cost of overcoming possible objections, whether or not they are valid, may make a development unviable. (j) It has been widely held that suitable plant and equipment were not readily available and that control equipment in particular was complex and expensive. The advent of micro-electronics for control and protection has an immense impact which has not yet been fully exploited. 6.3 Recommendations The working group was invited to make suggestions for further study or action, with the eventual objective of helping to overcome the main obstacles and stimulate new schemes. In so doing, the group draws attention to the Energy Act 1983 and emphasises its significance as a substantial step forward in removing obstacles to development; it considers that the full benefit of this Act has not yet been fully appreciated. It is perhaps too soon to gauge its effect. In making the following suggestions the group is conscious that, in some instances, it has not specifically identified a source of funding or parties responsible for action. In some cases it is believed that the Government would be the appropriate party. It is hoped that publication of this Watt Committee Report will stimulate further discussion and that from such interest will emerge positive action which will result in development of a substantial proportion of this untapped resource. (a) The basic facts of the Energy Act 1983 should be publicised by electricity authorities, drawing attention to the possibility of collaboration with private developers. (b) In order to simplify and clarify the rather confusing interface which continues to exist between Water Authorities and potential hydro-power developers, the Department of the Environment should consider issuing a Statutory Instrument or similar guideline, as appropriate, to achieve some measure of standardisation and consistency. It is hoped that this might result in

80 CONCLUSIONS AND RECOMMENDATIONS

either the abolition of the charge for abstraction for small hydro-electric developments (as in Scotland) or the introduction of a standard set fee, covering the necessary administration. (c) Reconsideration should be given by the Government to funding promotion and construction of pilot small-scale hydro-power developments with the object of identifying obstacles and recommending action to ease or remove such obstacles. (d) In any appraisal of economics, the funding agencies (public or private) should be encouraged to use more realistic return periods of ‘pay-back’, especially where the proportion of civil construction is high (say ten to fifteen years). (e) Government and European Economic Community should consider removing some of the restraints on grants to make them more accessible to conventional small-scale hydro-power development. The availability of such aid should be more widely advertised and the procedures for applications simplified. (f) Government should commission assessments of undeveloped potential in the U.K. where this has not already been done. This should include a schedule of the location of and current situation regarding former installations, say in excess of 50 kW potential. Such assessments, along with earlier studies, should lead to a situation where beneficial development is identified and possible developers are made aware of the potential. (g) Methods of dealing with objections should include means of obviating costs and delays; this is especially important where objections are suspected of being frivolous or spurious. (h) Manufacturers should be encouraged to standardise on and mass-produce mechanical, electrical and control equipment—a process which may help exports as well as development in the U.K.

Appendix 1 Sixteenth Consultative Council Meeting of the Watt Committee on Energy Small-Scale Hydro-Power

On 5th June 1984 the Watt Committee on Energy held the sixteenth in the series of its Consultative Council meetings. The theme was ‘Small-Scale HydroPower’, and the meeting was held at the City Conference Centre of the Institute of Marine Engineers, London. Those present were the secretaries and appointed representatives of the member institutions of the Watt Committee and others with professional interests in the subject of the meeting. Papers (listed below) were presented informally by members of the Watt Committee working group on Small-Scale Hydro-Power, and there were several periods of discussion. The contents of the papers form part of the present Watt Committee Report. As published here, the papers have been expanded and revised to present additional information for which there was insufficient time at the meeting and to take account of questions that arose in discussion (including subsequent written contributions). Programme of Meeting Session 1 Chairman: J.V.Corney (Institution of Civil Engineers) Official Opening by Dr J.H.Chesters OBE FEng FRS (Chairman, Watt Committee on Energy) J.V.Corney: Introduction Professor E.M.Wilson (Institution of Civil Engineers): The potential for smallscale hydro-power in the United Kingdom J.Taylor (Institution of Electrical Engineers): Mechanical and electrical plant and equipment for small-scale hydro-power N.A.Armstrong (Institution of Electrical Engineers and Institution of Mechanical Engineers): Civil engineering aspects Discussion Session 2 Chairman: H.W.Baker (Institution of Civil Engineers) E.C.Reed (Institution of Water Engineers and Scientists), D.J.Hinton (Institution of Civil Engineers) and A.T.Chenhall (Institution of Electrical Engineers): Institutional barriers to small-scale hydro-power development Discussion Session 3 Chairman: Professor E.M.Wilson

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A.T.Chenhall: Economics of small public and private schemes Discussion J.V.Corney: Concluding remarks Contributors to discussion W.R.Abram, South West Water P.W.Agnew, University of Glasgow J.H.Amos, Institution of Electrical Engineers J.M.Bain, Institution of Mechanical Engineers D.J.Banks, Institution of Civil Engineers Dr W.O.Binns, Chartered Institute of Foresters Commander G.C.Chapman, National Association of Water Power Users J.A.Crabtree, National Association of Water Power Users Dr P.J.Fenwick, Department of Energy Dr M.Flood, International Solar Energy Society—U.K. Section O.M.Goring, Water Power Engineering R.Holland, Institution of Electrical Engineers Dr P.O.McGovern, Scottish Development Department Planning Services Dr J.C.McVeigh, Institution of Production Engineers Dr M.Mansell, Institution of Civil Engineers P.Mason, Institution of Structural Engineers W.A.Patterson, Institution of Civil Engineers I.F.Seager, Institution of Electrical Engineers T.E.Truslove, Institution of Mechanical Engineers Dr M.L.Wright, Water Power Engineering

Appendix 2 Government grants and funding available by P.J.Fenwick Department of Energy, London

There are currently a number of schemes, funded both by the United Kingdom Government and the European Economic Community, which may be applicable for either the development or installation of small-scale hydro-power projects. The names and addresses given here were correct in February 1985. A.2.1 EEC Support for Demonstration Projects The European Commission will again be inviting applications in 1985 for the funding of the demonstration of hydro-electric schemes with outputs of up to 3 MW. The criteria for funding of up to 49% of the total cost are that the schemes should generally be of low head and be of a decidedly innovative character. General enquiries relating to the scheme may be made to: Dr G.Preston Department of Energy, Thames House South, Millbank, London SW1P 4QJ. Telephone 01–211 5461. A.2.2 Energy Efficiency Survey Grants: Department of Energy The Energy Efficiency Office at the Department of Energy has recently included the category ‘Use Renewable Energy Source’ as a recommendation which might be made under the grant-aided Energy Efficiency Survey Scheme. The purpose of the survey is to identify opportunities for potentially cost-effective improvement to energy efficiency, and the scheme offers a grant of 50% towards the cost of a survey carried out by an independent consultant. If, therefore, at a particular site, small-scale hydro-power were to offer one of the better opportunities for costeffective improvement, this would appear in the ranking of the recommendations made by the consultant. Further details of the scheme may be obtained from: Energy Efficiency Office,

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Department of Energy, Room 1697, Thames House South, Millbank, London SW1P 4QJ. Telephone 01–211 7074. A.2.3 Support for Innovation: Department of Trade & Industry This scheme provides general support to manufacturing organisation towards the costs of the research, design, development and launch of technically innovative products. Grants of up to 25% of the total costs are currently available. In the field of small-scale hydro-power, those proposals leading to the development of innovative equipment suitable for export markets would be particularly appropriate. Further information may be obtained from: Research & Technology Policy Division, Department of Trade & Industry, 24 Bressenden Place, London SW1E 5DT. Telephone 01–213 5839. A.2.4 Research and Development Funding: Department of Energy The Department of Energy provides research and development funding for a range of energy projects, including the renewable energy sources such as smallscale hydro-power. The Department’s primary objective is to investigate potentially significant new and renewable forms of energy and assess what contribution they might make to U.K. energy supplies in the longer term. Support for the development of selected promising ideas, techniques or equipment is assessed in terms of its contribution towards achieving the Department’s primary objectives. Further details may be obtained from: Mr W.Macpherson, Department of Energy, Thames House South, Millbank, London SW1P 4QJ. Telephone 01–211 6580.

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A.2.5 Regional Development Grants: Department of Trade & Industry The installation of a small-scale hydro-power scheme may in specific circumstances qualify for support under the general criteria of the regional development grants. These grants are primarily designed to encourage investment in new capital assets for manufacturing activities located in specifically designated geographical areas. Grants of up to 22% are available towards the capital expenditure incurred in providing new buildings, works, machinery on plant for use on qualifying premises. Further information may be obtained from: Regional Policy and Development Grants Division, Department of Trade & Industry, Room 429, Kingsgate House, 66–74 Victoria Street, London SW1E 6SJ. Telephone 01–212 6712.

Appendix 3 Use of water for milling or power generation: circumstances in which a licence is required Memorandum by the Department of the Environment and Welsh Office NOTE. In supplying a copy of this Memorandum, which was prepared in August 1974, the Department of the Environment draws attention to changes in the circumstances, especially the level of charges, that may have occurred since. 1. Following representations made to the Parliamentary Commissioner for Administration regarding charges for abstraction of water for the purpose of flowing over waterwheels or turbines in order to generate power or operate machinery, it was found that there were to some extent differing views among the former river authorities as to the licenseability of such uses. Added to this was the fact that, in some areas, use of water for power generation was either minimal or it had little effect on resources and had therefore been exempted from charge, while in other areas such uses had considerable effect on the resources of particular areas. This led to variations in charges to perhaps a greater degree than was normal in the case of other uses which every river authority considered licenseable and appropriate for charge. 2. In consequence, the Commissioner suggested that it might help to reduce inconsistency if the Secretary of State gave his views on the subject of licenseability, although he recognised that such advice would have no force in law. As the Water Resources Act stands at present, there is no provision for the Secretary of State to determine whether the taking of water in any set of circumstances is a licenseable abstraction under the Act. Moreover, because of the many different physical circumstances governing the use of water for power generation, it is impossible to cover every instance, but the following covers the more usual situations. 3. Where water for power generation is concerned, that part of the operation where water is actually flowing over turbines is of itself unlikely to constitute an abstraction so that the point to be resolved is, normally, whether a licenseable abstraction is taking place in order to get water to the point where it will flow over the turbines or wheels. Then, if abstraction is taking place within the meaning of section 135 of the Act, the abstractor requires to obtain from the appropriate water authority a licence authorising that abstraction. He is then liable to whatever is the appropriate charge under the authority’s current charging scheme. Set out below are views on some fairly basic types of circumstances, although it is recognised that there may be many variations.

APPENDICES 87

Figure A.1 Scheme involving no abstraction.

4. Under section 23(1) of the Water Resources Act 1963 no one may abstract water from a source of supply except in pursuance of a licence. (There are certain minor exceptions such as abstraction of water for the domestic purposes of an individual household). The definition of ‘abstraction’ in section 135(1) of the Water Resources Act 1963 is as follows:‘“abstraction”, in relation to water contained in any source of supply in a river authority area, means the doing of anything whereby any of that water is removed from that source of supply and either— (a) ceases (either permanently or temporarily) to be comprised in the water resources of that area, or

88 APPENDICES

Figure A.2 Scheme involving abstraction.

(b) is transferred to another source of supply in that area, and “abstract” shall be construed accordingly’. ‘Source of supply’ is also a term of art (section 2 and section 135(1), especially the definitions of ‘inland water’ and ‘watercourse’), but in addition to rivers and streams it includes passages through which water flows, subject only to limited exceptions which are virtually certain to be immaterial in the present context. 5. The use of water to drive wheels or turbines seems unlikely of itself to constitute an abstraction at that point of the operation. (Where there is some fall of water on to a wheel, the time during which the water is not in a ‘source of supply’ is so short it is thought that the maxim de minimis would normally

APPENDICES 89

Figure A.3 Abstraction from primary leat to secondary leat at sluice.

apply). Where a sluice-gate is in a stream and it is operated to allow water to flow directly onwards to turn a turbine or waterwheel sited in that stream, the operation of the sluice gate merely allows water to flow on within the same source of supply and therefore water is not being removed from a source of supply nor is it transferred from one source to another, so no abstraction is taking place within the meaning of the Act. 6. A licenseable abstraction for the purposes of power generation therefore usually arises from diversion of water, e.g. the removal of water from a stream to

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Figure A.4 Abstraction from river but not from leat: abstraction is considered to occur at A but not at B.

the mill leat (a different source of supply) where the turbines or mill wheel are placed, and then only if there is a sluice gate or other form of regulator to which something is ‘done’ (turned, raised, etc.) in order to ‘remove’ water from the stream, the original source of supply, and transfer it to the other source of supply (the mill leat). The most usual form is the weir on the main stream which impounds the flow to get a head of water, which is then released into the leat by

APPENDICES 91

Figure A.5 Abstraction through pipeline.

means of a sluice gate at or near the junction of the stream and the leat. In certain cases, this sluice gate may be positioned farther down the leat itself instead of at or near the stream, but it may have the same effect. When the sluice gate is shut, water is ponded back as far as the entrance to the leat and forms a barrier which prevents more water flowing from the main stream into the leat. When the sluice gate is opened, the effect is to ‘remove’ water from the stream by allowing it to flow into the leat. 7. A series of sketches is attached showing various circumstances and indicating whether or not the Department considers abstraction is taking place.

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Figure A.6 Arrangement with separate channels for turbine and overflow below sluice: no abstraction.

Appendix 4 National Association of Water Power Users: Paper for the Watt Committee

Note This paper was presented at a meeting of the Watt Committee working group on 2 December 1983. A.4.1 Aim This paper aims to present to the Watt Committee’s Working Group on SmallScale Hydro-Power the views of the National Association of Water Power Users (NAWPU), and of some members of its Council, in answer to the questions posed in the Working Group’s Terms of Reference, and in correspondence. A.4.2 Background The NAWPU was formed in 1975 principally to ease, for water power users, the constraints caused by the Water Resources Act 1963, and the various Electricity Acts; the former leading Water Authorities to charge for so-called ‘abstraction’, and the latter restricting the activities of private generators of electricity in relation to the nationalised electricity supply industry. The Association’s aims include promotion of water power use, and steps are at present being taken to improve the service to members in this direction. The Association welcomes the opportunity to assist the Working Group and looks forward to seeing its report in due course. A.4.3 Questions The questions to be answered are, we believe: (1) What is the potential for further small-scale hydro-power development in the United Kingdom? (2) What factors inhibit such development? (3) What plant is available in the U.K.? (4) What is the export potential?

94 APPENDICES

A.4.4. Definition ‘Small-scale’ is obviously relative. We wish to draw no hard and fast upper limit, but to suggest that perhaps the 10-MW level (see Energy Act 1983, Section 2) below which private generators do not need to inform their Area Board might be appropriate. While a lower limit is perhaps unnecessary, it is worth remarking that the lowest energy levels we have found in use which either are, or could be, hydropowered, are in the order of 200 Wh per day for domestic lighting: a hydraulic ram is comparable. As insulation levels of houses improve— and conversion efficiency of e.g. lighting appliances—so demand is falling. A.4.5 Potential for Further Small-Scale Hydro-Power Development in U.K. NAWPU membership has been something over 200 for most of its eight years of life, with around 350 people or firms being members at one time or another. Many more eligible users and interested people have enquired. Currently, a majority of members are either water power users or have projects in mind or hand and it is likely that they are a representative sample. Nevertheless, the NAWPU membership is a small proportion only of water power users. One report1 put the number of working water-power sites in England in the peak period of the 1800s at over 20000; another has identified over 600 usable sites of over 25kW in Wales.2 Francis in 1978 put the usage at 370.3 So if England and Wales have say 21000 sites, perhaps 900 are in use. In the U.K. as a whole there may be around 1000 in use, with the potential to develop another 20000 at least. This number can possibly be increased, since its basis is the relatively low number of sites associated with water-wheels. Use of longer pipelines, higher head and turbines and modern dam-building, on the one hand, and low-head turbines, on the other, will widen the scope for finding sites, though this will be offset to some extent where various factors, e.g. depletion of river flows by (genuine) abstraction, have rendered old sites unusable. As a matter of observation, virtually all usable water-wheel sites have been exploited at some time or other. Francis estimated the potential energy available from the usable sites that he identified at 0.7M tons of coal equivalent per year—say 1.4×109kWh/year or 160000kW continuously. If this were to be generated by 21000 units, the average power output would be 7.6kW—which sounds reasonable. Not only is this energy important nationally, it can make a very useful and economic contribution to many businesses and individuals.

APPENDICES 95

A.4.6 Factors Inhibiting Development Water resources The Water Resources Act 1963 took no account of the use of water for energy production, and the definitions of ‘abstraction’ (Section 135(1)) and ‘source’ (Section 2(1)) are such that Water Authorities regard any device other than an undershot wheel placed in a river as ‘abstracting’. This has not, as far as we know, been challenged in the Courts. From this the Water Authorities have insisted that commercial users be licensed and charged both a fee for the licence (Section 57) and a charge based on the quantity of water used (Section 58 (2)). After much work by the Association and others, the Energy Conservation Act 1981, Section 16, added a paragraph to Section 60(2) of the 1963 Act telling Water Authorities to ‘have regard to…the need to conserve sources of energy (other than water) and the consequent desirability of preventing the charges in question from inhibiting the use of water as a source of energy’. This was after Ministers had agreed that for energy use a licence fee to cover the administrative cost was all that was justified. Regrettably Parliament—or the Departments—did not see fit to amend or repeal Section 58(2) and the Welsh Water Authority (for one at least) continues to attempt to exploit that section. Indeed, in addition, they seem intent on charging not only on a basis of quantity but also for the length of leat or pipe; the greater the distance over which the water is ‘abstracted’ from the main stream, the more you pay. At the same time, Water Authorities are inviting users to submit financial accounts to show the extent to which an ‘abstraction’ charge would render a scheme unprofitable: presumably with a view to setting the charge at such a level that the scheme is sufficiently profitable for the owner to go ahead—or not shut down an existing plant. This really can only be described as waterway robbery. The merit of waterpower is that the fuel is not only from a self-refilling source, but it is ‘free’ in the sense that the delivery system is very largely provided naturally. Some places even have to spend money to prevent a surplus of fuel causing damage. To levy a charge for water so that a user is just kept from using a fossil-fuel source is indefensible—but this is what is proposed. There is an element of iteration here. If the price of Electricity Board energy is used as a comparator in the assessment of a private plant’s fee, and that price is already higher than it might otherwise be because the CEGB is paying an ‘abstraction’ charge then…! Again, this has not yet been fully put to the test in negotiation or the Court, or by appeal to the Minister. The CEGB, be it noted, is not a member of NAWPU. Electricity generation The Energy Act 1983 permits private generators of electricity to buy and sell from and to the Boards and to use the Boards’ lines to

96 APPENDICES

supply private consumers. SWEB have recently published their tariffs. While these set out the various charges they no more than mention the metering and other arrangements which have been used in the past (by some Area Boards) to discourage private generation, whatever the prime mover. It is perhaps too soon to assess the effect of the 1983 Act; but it is worth pointing out that the potential total of small-scale hydro-electricity power is around 160MW made up of many small units, and this should be seen in relation to the CEGB’s total capacity and output. It is also worth noting that the CEGB’s own small hydro-power plants in Devon (a total of 3.34MW at three sites) are shut down at night, presumably because the cost of watch-keepers at night, together with the abstraction charges, renders them uneconomic in relation to the coal- and nuclear-fired base generators. Costs It seems that many potential users are advised by their accountants to seek a 2–3–4-year payback period for a hydro-power plant. It is the accountants who need to be convinced of the merits, in the long term, of investment in hydropower where the payback period is of the order of 10 years and the life 50 to 100 years. One question for the accountants to answer is, ‘What capital sum must be invested to be sure that the net interest (after tax and inflation) will pay the electricity bill for ever?’ Even so, there is a belief among some small hydro-power engineers that there is a tendency to over-design, and where a system designer is new to the subject this is understandable. As a designer gains experience, he can simplify; this can lead to considerable cost reduction. The NAWPU list of ‘Experts’ includes, besides those who manufacture or sell equipment, a number of consultants. Perhaps it is revealing that none of them claims to specialise in, e.g., surveys of water resources or design or installation of complete systems. Generally, people with a stream or river or derelict mill have difficulty in finding anyone who admits to having the knowledge, skill and time to survey, design and install a scheme and to quote for or estimate the cost. Where schemes are started they seem, in general, to take longer to complete than the customer thinks necessary. As often as not, the customer himself undertakes some of the installation and civil engineering work. To date, the industry has not ‘taken off, or rather, recovered the situation of the late 1700s, when the collective knowledge and experience of water power was held partly by millwrights and partly by users (millers, farmers, industrialists) and was considerable and widely available. Generally, there are probably enough chartered and other engineers either already on the NAWPU list or lurking in the background to meet a bigger demand than exists at present: very few are over-worked. As long as demand is constrained for any of the other reasons, an apparent shortage of qualified, experienced people who are prepared to build schemes cheaply (with a proven record of success) further restricts demand.

APPENDICES 97

One of the few bonus points is that at many disused sites much of the survey has already been done and the civil engineering assets would be readily restorable. A.4.7 Plant Available in U.K. Of manufacturers or agents (including those who are members of NAWPU),* the breakdown is: Turbines, 8 Water-wheels, 1 Electronic load controllers, 5 Generators, 4 This list is certainly not exhaustive. Of the makers of electrical generators, all make brushless machines for outputs from 3kW upwards, and there are more firms who make larger machines. A wide range of machines is available from stock and on the second-hand market. There is also a handful of firms and individuals who restore old hydro-power plant and machinery. Restoration for museum use with sales, e.g. of stoneground organically grown flour, does seem to be a growth activity. We suggest that the manufacturers should be asked to give details of their products and where they may be seen in manufacture and in operation. A.4.8 Export Potential NAWPU is in no position to assess the export potential of small hydro-power plant. What we would say is that the world is a much smaller place with a better educated population than it was 150 years ago, when the U.K. could find a ready market for its manufactures and expertise overseas. Today the capability of some people in virtually every country to engage in ‘state of the art’ small-scale hydropower development, manufacture and installation is as good as that in the U.K., and the capacity—on account of lower wages and less rigorous engineering and safety standards—is frequently greater. As often as not, we can learn from them. Our ability to exploit any export potential will depend on the same factors as affect potential at home, and also on our ability to produce better products more cheaply, to time and within budget. Possibly systems expertise has a greater export potential than straight manufacture.

* See Table 2.4, page 20.

98 APPENDICES

One body which has concerned itself with aid to developing countries (and aid to our own exports) is the Intermediate Technology Development Group. References 1. 2. 3.

Weisbach, J. A Manual of the Mechanics of Engineering &c. Translated by A.Jay du Bois, Vol. 2, John Wiley & Sons, New York, 1880. Hydro-power potential in Wales. A Report for the Department of Energy, by Professor E.M.Wilson, Salford University, Oct 1980. Francis, E.E. An Appraisal of the low head and run-of-river water power in England and Wales. Dept of Energy, 1978.

Appendix 5 Abbreviations Used in this Report

Abbreviations used in this Report, and certain other abbreviations that are likely to be encountered, are listed here. The units and other abbreviations used vary, in some instances, according to common practice, although the units of the Système Internationale (S.I.) are usually preferred. Conversion factors and approximate equivalents for certain quantities that occur frequently are also given, but it should be remembered that approximate equivalents are not suitable for accurate calculations, for which accurate equivalents must be used. Organisations CEC CEGB CERL EEC

ESRC IEC NAWPU NCB NIES NSHEB OECD SSEB WMO UN UNEP UNECE

Commission of the European Communities Central Electricity Generating Board Central Electricity Research Laboratory (CEGB) European Economic Community (‘the Community’, whose power is exercised by the Commission of the European Communities—‘the European Commission’—under the policy direction of the Council of Ministers subject to the powers of the European Parliament) Electricity Supply Research Council International Electrotechnical Commission National Association of Water Power Users National Coal Board Northern Ireland Electricity Service North of Scotland Hydro-Electric Board Organisation for Economic Co-operation and Development South of Scotland Electricity Board World Meteorological Organisation United Nations United Nations Environmental Programme United Nations Economic Commission for Europe

100 APPENDIX

Units Length m mm km Area ha Volume/capacity 1 Mass (weight) g kg t Power W kW MW Energy kWh MWd GWy J MJ GJ EJ Btu Electric current A V kV MV Force N Pressure atm

metre (1 m=1000 mm=1.094 yard=3.28 ft) millimetre (1 mm=0.03937 inch) kilometre (1 km=1000 m=0.621 mile) hectare (1 ha=10000 m2=2.47 acre) litre=(1 l=10−3 m3=1.759 pint=0.220 gallon (Imp.)) gram (1 g=1000 mg=0.0353 oz) kilogram (1 kg=1000 g=2.205 lb) tonne (1 t=1000 kg=0.9842 ton) watt (1 W=1 J/sec=1 VA=9.478×10−4 Btu/sec) kilowatt (1 kW=1000 W=1.341 horsepower) megawatt (1 MW=1000 kW=106 W) kilowatt hour (1 kWh=3600 kJ=3.412 Btu) megawatt day (1 MWd=24000 kWh) gigawatt year (1 GWy=365000 MWd) joule (1 J=1 Nm=0.0009478 Btu) megajoule (1 MJ=106 J=9.478×10−6 therms) gigajoule/1 GJ=103 MJ=109 J=9.478×105 Btu=9.478 therms) exajoule (1 EJ=1018 J=1 Q=1015 Btu (quadrillion Btu)) British thermal unit ampere volt kilovolt (1 kV=1000 V) megavolt (1 MV=1000 kV=106 V) newton (1 N=1 kg m/sec2) atmosphere (1 atm=101325 N/m2 =4.7 lbf/in2 =1013.2 millibar)

Approximate equivalents 1 tonne of coal equivalent (1 t.c.e.) =26 GJ =0.6 t.o.e. (tonnes of oil equivalent)

THE WATT COMMITTEE ON ENERGY 101

106 t of coal

=7250 kWh electrical energy (total energy) =675 m3 of natural gas =25.5×1012 Btu

Other CBR CHP FDC IRR LRMC MWSO NEC NPV pmf PP TDR

cost-benefit ratio combined heat and power flow duration curve internal rate of return long-run marginal cost megawatts sent out (i.e. net of station auxiliary power) net effective cost net present value probable maximum flood payback period test discount rate

THE WATT COMMITTEE ON ENERGY

GENERAL OBJECTIVE The objective is to promote and assist research and development and other scientific or technological work concerning all aspects of energy and to disseminate knowledge generally concerning energy for the benefit of the public at large. TERMS OF REFERENCE The Watt Committee on Energy, being a Committee representing professional people interested in energy topics through their various institutions, has the following terms of reference: — 1. To make the maximum practical use of the skills and knowledge available in the member institutions to assist in the solution of both present and future energy problems, concentrating on the U.K. aspects of winning, conversion, transmission and utilisation of energy and recognising also overseas implications. 2. To contribute by all possible means to the formulation of national energy policies. 3. To prepare statements from time to time on the energy situation for publication as an official view of The Watt Committee on Energy in the journals of all the participating institutions. These statements would also form the basis for representation to the general public, commerce, industry and local and central government. 4. To identify those areas in the field of energy in which co-operation between the various professional institutions could be really useful. To tackle particular problems as they arise and publish the results of investigations carried out if suitable. There would also, wherever possible, be a follow-up. 5. To review existing research into energy problems and recommend, in collaboration with others, areas needing further investigation, research and development. 6. To co-ordinate future conferences, courses and the like being organised by the participating institutions both to avoid overlapping and to maximise cooperation and impact on the general public.

THE WATT COMMITTEE ON ENERGY 103

EXECUTIVE COMMITTEE as at March 1985: Chairman Dr J.H.Chesters, O.B.E., F.Eng., F.R.S. Deputy Chairman Dr G.K.C.Pardoe E.A.Alcock, Institute of Cost and Management Accountants (Hon. Treasurer) Professor W.O.Alexander, Institute of Metals J.W.Rogers, Institution of Civil Engineers H.Brown, Institution of Plant Engineers R.F.C.Butler, International Solar Energy Society (U.K. Section) Professor I.C.Cheeseman, Chartered Institute of Transport J.Boddy, Institute of Petroleum Professor A.W.Crook, Institution of Mechanical Engineers R.S.Hackett, Institution of Gas Engineers Dr A.F.Jackson, Institution of Electrical Engineers Dr E.G.Masdin, Institution of Chemical Engineers Dr J.R.Milford, Royal Meteorological Society W.B.Pascall, Royal Institute of British Architects W.Ridley, Society of Business Economists Dr P.A.A.Scott, Royal Society of Chemistry A.Silverleaf, Royal Institution of Naval Architects Professor A.J.Smith, Geological Society of London Professor J.Swithenbank, Institute of Energy E.L.Walker, Institute of Purchasing and Supply N.G.Worley, British Nuclear Energy Society J.G.Mordue, Secretary Note: A part of the executive rotates on an annual basis at 30th April each year. The following institutions were members of the executive for the years shown: 1983/84 British Association for the Advancement of Science Hotel Catering and Institutional Management Association Institute of Chartered Foresters Institution of Agricultural Engineers Institution of Electronic and Radio Engineers Institution of Water Engineers and Scientists 1984/85 Geological Society of London Institute of Purchasing and Supply Institute of Metals International Solar Energy Society (U.K. Section) Royal Institution of Naval Architects Royal Meteorological Society

Dr J.G.Collingwood M.J.Moore J.N.R.Jeffers J.C.Weeks R.F.C.Butler C.Cash Professor A.J.Smith E.L.Walker Professor W.O.Alexander R.F.C.Butler A.Silverleaf Dr J.R.Milford

Small Scale Hydro Power

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