Energy can neither be created nor destroyed. Energy can only be converted from one form to another. E.g. if we drop a plate from a height, the potential energy of the plate gets converted mostly to sound energy when it hits the ground, chemical energy in the wax is converted to heat energy & light energy on burning. The total energy during a physical or chemical process remains the same. In the above examples, energy in the usable form is dissipated to the surroundings in less usable forms. Hence, any source of energy we use, to do work, is consumed & can not be used again. CLASSIFICATION OF SOURCES OF ENERGY:
The sources of energy are usually classified either as:
1. Renewable and Non-renewable source of energy.
2. Conventional & Non-conventional source of energy.
Renewable sources of energy:
• Renewable sources of energy are those which are inexhaustible i.e. which can be replaced as we use them & can be used to produce energy again & again. • These are available in an unlimited amount in nature & develop within a relatively short period of time. • E.g. solar energy, wind energy, water energy, geothermal energy, ocean energy, biomass energy (We can get a continuous supply of biomass only if we plant trees in a planned manner. In case, it is not done so, we would fall short of biomass), nuclear energy (Nuclear energy is also inexhaustible as only small mass of uranium produces large amount of energy, e.g. one atom of uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal.) Non Renewable sources of energy:
• Non renewable sources of energy are those which are exhaustible & can not be replaced once they have been used. • These sources have been accumulated in nature over a very longer period of million of years. • E.g. fossil fuel like coal, petroleum, natural gas.
Conventional source of energy:
• Conventional sources for energy are those which are used extensively & meet a major portion of our energy requirement. • e.g. fossil fuel (coal, petroleum, natural gas), hydro-energy. • Conventional sources also include biomass energy & wind energy as these are also used from ancient times. Non Conventional sources of energy:
• Non conventional sources of energy are those which are not used as extensively as the conventional ones. These partially meet our energy requirements. • Solar energy, ocean energy (tidal energy, wave energy, ocean thermal energy), geothermal energy & nuclear energy belong to this category. These sources of energy which have been tapped with the help of advanced in technology to meet our growing energy needs are also called alternative sources of energy.
FOSSILS FUEL: The fuels which are obtained from the remains of plants & animals are called fossil fuels. E.g. coal, petroleum, natural gas. The remains of plants & animals which got buried inside the earth million of years ago, changed into coal, petroleum & natural gas due to excessive heat & high pressure inside the earth. • The coal as a source of energy made the industrial revolution possible. • Fossil fuels is a major fuels used for generating electricity, in gas stoves & for running vehicles. • The growing demand for energy is largely met by fossil fuels-coal & petroleum. • There are only limited reserves of fossil fuels. The fossil fuels are non-renewable sources of energy. So we need to conserve them. If we continue consuming these fossil fuels at such alarming rates, petroleum will be finished in next 40 years & coal in next 100 years. In order to avoid this, alternate sources of energy were explored.
Disadvantages of using fossil fuel:
(i)Burning of coal & petroleum lead to air pollution. The oxides of carbon, nitrogen & sulphur that are released on burning fossil fuels are acidic oxides. These lead to acid rain which affects our water & soil resources....