Energy Sources and Transfer of Energy

(d) list renewable and non-renewable energy sources. (e) describe the processes by which energy is converted from one form to another, including reference to (1) chemical/fuel energy (a re-grouping of atoms), (2) hydroelectric generation (emphasising the mechanical energies involved), (3) solar energy (nuclei of atoms in the Sun), (4) nuclear energy, (5) geothermal energy, (6) wind energy. 

Fuel energy involves reduction-oxidation reduction-oxidation chemical reactions that generate heat (exothermic), that heat is then converted to mechanical energy using energy using a working fluid passing through some machine which in turn powers an alternator (or generator) which converts mechanical energy to electrical energy to keep my computer running. Hydroelectric generation converts gravitational potential energy into energy intokinetic kinetic energy (moving energy (moving water) which is converted into mechanical energy by a turbine which spins an alternator which converts mechanical energy into electrical energy.

Renewable/ S.No

Type of Non-

Energy

Renewable

Wind 1

Renewable

Renewable

Energy Conversion

Advantages

Disadvantages

1-renewable.

1-Expensive at installation time.

Kinetic to

2-No CO2 pollution.

2-Dangerous for birds.

Electrical

3-Very cheap Electricity after

3-Visual and Noise pollution for for

few years.

large production.

1-renewable.


GPE to

2- No CO2 pollution.

2-Dangerous for wildlife.

Electrical

3- Very cheap Electricity

3-Visual pollution for large

after few years.

production.

Main Source: Sun

2 Water

Form of

1-renewable. 3

Geothermal Resource

Renewable

Thermal to



Electrical

3- Very cheap Electricity

2-Not available everywhere.

after few years.

4

Solar Heating Systems

Renewable

Light to

1-renewable.

Thermal


1-Expensive at installation time. 2-Dangerous for wildlife. 3- If there is no Sun it won't work.

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Renewable/ S.No

Type of Energy

Form of Energy Non-

Conversion

Advantages

Disadvantages

1-renewable.

1-Expensive at


installation time.

3- Very cheap


Electricity after few

3-Visual pollution for

years.

large production.

1-renewable.

1-Expensive at


installation time.

3- Very cheap




years.

large production.

1-renewable.

1-Expensive at


installation time.

3- Very cheap




years.

large production.

Renewable

5

6

7

Solar Cells

Fossil Fuels

Nuclear Power

Renewable

Renewable

Renewable

Light to Electrical

Chemical to Electrical

Nuclear Potential Energy to Thermal + Kinetic

Try following question

(f) explain nuclear fusion and fission in terms of energy releasing processes. Fission: Splitting of atom is called fission. Atoms store large amount of energy-- just like stretched catapult!. Which upon its release return stored energy. Similiarly, when atoms are split they release a large amount of energy in the form of heat and light.



when atoms are joined they store that energy in them—however, while storing energy they kind of vomit energy out as well. So in every fusion process energy is released in the f orm of heat and light.

(g) describe the process of electricity generation and draw a block diagram of the process from fuel input to electricity output.

(h) discuss the environmental issues associated with power generation. As discussed in the advantages and disadvantages in table given.

(j) calculate the efficiency of an energy conversion using the formula efficiency = energy converted to the required form/total energy input. (k) discuss the efficiency of energy conversions in common use, particularly those giving electrical output.



The key to understand the efficiency concept is to understand the concept of “useful energy” and “input energy.”

The amount of energy that is put into the system is called Input Energy. For example, the amount of fuel that is poured into the car’s tank is the input chemical energy.

The useful output energy that we need from chemical energy is movement energy (we need car to move), light energy (head lights etc) and Sound energy (horn). However, Heat is not useful energy and therefore called waste energy. Unfortunatley, in any process some amount of undesirabel energy is always produced. This is called waste energy. Efficiency is defined as the ability of any device or process to transform maximum amount of input energy into useful form. Useful energy is different for different system e.g.; for light bulb the useful energy is light not heat, for bicycle it’s the movement energy, for horn it is the sound energy.

Look at the following diagram.



Try question on following page

(b) The lamp is of 100 W and is only 5% efficient. What does this mean? ........................... ....................................... ......................... .......................... ......................... .......................... ........................... .......................... ............................... .................. ........................... ....................................... ......................... .......................... ......................... .......................... ........................... .......................... ....................... .......... (2) Solution: (a) Electrical to

light & heat

(b) That only 5 J of Electrical energy is converted into Light. Rest is wasted into heat.



Energy Sources and Transfer of Energy

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