Secondary energy resources are those which do not occur naturally but which are obtained from one or more of the primary energy resources.
Example: Petrol or gasoline, electrical energy from coal burning, hydrogen obtained by electrolysis of water etc.
Non-commercial source of energy: Firewood, cow dung, and vegetable wastes.
Commercial sources of energy: Electricity and gas are termed as commercial fuels. In India, the consumption of commercial energy has been going up by about seven per cent per annum.
This table gives the current assessment of the potential of non-conventional sources of energy and their present status of development.
Conventional sources of energy: Crude oil, natural gas, Hydel, nuclear etc. are termed-as conventional sources of energy.
Non-conventional source of energy: These include solar, wind, geothermal, ocean, and hydrogen energy.
Since resource endowment is a primary dimension of sustainability, we may now examine the current situation in India. Despite her large geographical area of 328 million hectares, India’s primary energy reserves are not substantial. The table shows the total and per capita availability of conventional energy resources, their life span and implications on the energy future of the nation.