Sources of energy Worksheet-5
(a) Renewable and non-renewable?
(b) Exhaustible and inexhaustible?
Are the options given in (a) and (b) the same?
(i) Tidal energy : Very few suitable sites are available for construction of dams and the power generation is intermittent and not very large.
(ii) Wave energy : Where power output is variable and the presently available technologies are very expensive.
(iii) Ocean thermal energy : Where the conversion efficiency is low (3% - 4%) and a lot of capital investment is required.
2. The nuclear fuel supplies energy over a long span of time.
These sources were formed over millions of years under special conditions.
Fossils fuels cause pollution on burning whereas solar energy is pollution free.
Fossil fuels can provide energy at any required time whereas solar energy becomes unavailable when the sky is covered with clouds.
Fossil fuel is expensive and solar energy is free.
(ii) The energy from bio-mass can be obtained by using a chullha or a gobar gas plant whereas hydro-electricity requires construction of dams on rivers.
(iii) Bio-mass provides pollution-free energy only when converted into biogas whereas hydroelectricity is fully pollution-free.
(i) They can be replaced as we use them
(ii) They can be used to produce energy again and again.
Non-renewable sources of energy
1. They cannot be replaced once these are used.
Exhaustible sources of energy
Their supply is limited, e.g., coal, petroleum and natural gas.
Inexhaustible sources of energy
Their supply is unlimited, e.g., solar energy, water energy, wind energy, nuclear energy etc.
Renewable sources of energy are inexhaustible whereas non-renewable sources of energy are exhaustible with some exceptions.
For example, biomass is a renewable source of energy only if we plant trees in a planned manner. On the other hand, geothermal energy and nuclear energy though inexhaustible are non-renewable.
(ii) Construction of dams on rivers to generate hydroelectricity destroys large ecosystems which get submerged under water in the dams. A further, large amount of methane, which is a greenhouse gas, is produced when submerged vegetation rots under anaerobic conditions.
Measures to be taken to reduce energy consumption :
(i) Fossil fuels should be used with care and caution to derive maximum benefit out of them.
(ii) Fuel saving devices should be used for example solar cookers, pressure cookers..
(iii) Efficiency of energy sources should be maintained by regular servicing.
(iv) We should be economical in our energy consumption as energy saved is energy produced.