Wind and running water as sources of energy, were in use long before the conventional sources of energy like coal, mineral oil and natural gas came- to be used widely. Windmills were used for pumping water and for grinding grains, respectively. Wind and running water were also used for navigation.

Today non-conventional sources energy includes wind, tides, solar geo-thermal heat, biomass including farm and animal waste as well as human excreta. All these sources are renewable or inexhaustible. They are inexpensive in nature.

Wind Energy
It can be used for pumping water, a prime need in irrigating farms in the countryside. Also, it can be used for generating electricity. The states of Gujarat, Tamil Nadu, Maharashtra and Orissa are better places in regard to this energy. Areas with constant and high speed winds are suitable for the purpose. Besides windmills, there are also wind farms.

Tidal Energy
This is another unlimited and inexhaustible six source of energy. The Gulfs of Kutch and Cambay are ideally suited to develop electricity from the energy produced by high tides entering into narrow creeks.

Solar Energy
The most abundant and inexhaustible source of energy is the sun. It is a universal source and has huge potential. A notable achievement has been the solar cookers. They help in cooking food almost without any-cost. Small and medium size solar power stations are being planned for rural areas. The successful applications of the solar energy so far have been for cooking, water heating, water desalination, space heating, crop drying. It is going to be the energy of future when fossil fuels, namely coal and oil, would be totally exhausted.

Thermal Energy
India is not rich in this source. However, efforts are on to utilize natural energy of the hot springs at Manikaran in Himachal Pradesh. Energy so produced can be used for running cold storage plants.

Biomass
The efforts are being made in India to make use of biomass in an efficient and more scientific manner. The two main components of the biomass programme are production and utilisation of biomass.

(i) Energy Plantation
Waste and denuded lands are being used for plantation of fast growing shrubs and trees with high calorific value. They in turn provide fuel wood, charcoal, fodder, power (and also scope for rural employment. Through the gasification system these energy plantations over 8,000 hectares were producing nearly 1.5 mw power, annually.

(ii) Energy from Urban Waste
A pilot plant for demonstration purposes has already been set up in Delhi to treat solid municipal waste for conversion into energy. It produces nearly 4-mw energy every year. Sewage in cities is used for generating gas and electricity.

(iii) Bagasse Based Power Plants
It is estimated that sugar mills in India can generate 2,000 mw surplus electricity during crushing season. Out of 10 mw energy produced by a mill of a given size, 4 mw would meet its own power requirements and the rest of 6 mw energy can be utilized in. irrigating fields by feeding it into the local grid.

Like bagasse several other farm wastes such as rice husk are also being used to produce electricity.

(iv) Farm, Animal and Human Wastes
By using farm and animal wastes as well as human excreta, "gobar gas" plants are being set up in villages to make them self sufficient in their power requirements. The power so produced is used for cooking, lighting homes and streets and meeting irrigation needs of the village. The plants are being set up both at individual and community or village levels. Sewage from large cities can be used for generating biogas.

(v) Smokeless Chulhas The largest share of energy is used in the country in millions of our kitchens. Wood and cowdung have been the universal sources of energy. Unfortunately the traditional chulhas are wasteful means of cooking food. There were nearly 28.5 million improved varieties of efficient and smokeless chulhas in operation till 1998. They help in saving firewood to the tune of 20 to 35 percent. Nearly 11 million tonnes of firewood is saved annually through these chulhas. They help in avoiding health hazards like sour eyes.