It was the energy crisis of 1973 and 1978 which forced people to recognize the vulnerability of oil-based economy all over the world and sincere efforts were undertaken to develop non- conventional sources of energy. In India also efforts to utilize non-conventional, renewable sources of energy were started only during seventies and a separate Department of Non-conventional Energy Sources (DNES) was established.
Conventional sources of energy, coal, oil, natural gas and nuclear energy - are non-renewable and their use is invariably associated with problems of environmental pollution. Hydro-electric power generation has its own drawbacks. Large-scale use of wood which is important source o energy in Indian villages leads to deforestation.
Moreover, the centralized system of power generation which we have developed with conventional sources of energy involves huge distribution networks. These are wasteful and expensive to maintain.
Non-conventional sources provide energy in decentralized manner to small areas and can reach places where it is difficult to carry fossil fuels or power lines. Large-scale use of non-conventional energy resources tends to reduce the burden from conventional energy systems and therefore is helpful in enlarging their life span. The Indian efforts in the direction of utilizing non-conventional energy resources have been centred around the following major sources:
An enormous amount of energy is available in the form of sunshine in our country which provides light as well as heat. Solar heat can be trapped by using simple reflecting devices which concentrate solar energy to a particular area. Department of Non-conventional Energy Sources has been trying to popularize the use of solar cookers and solar water heating devices by providing large subsidies to the consumers. Solar water heater, solar drier and desalinization plants have already become popular in India at a number of places.
2. Conversion of Solar Energy into Electricity:
Solar photovoltaic modules can convert solar energy into electricity. A large number of these modules are arranged on a panel which is called Solar panel which can either be directly connected] to the energy-using device or indirectly to batteries so that the electricity generated could be used Later when there is no sunshine. In India Solar photo-voltaic systems are being installed by Department of Non-conventional Energy Resources for lighting, running of television sets and radios, pumping water in remote area where it is difficult to carry electricity.
The Department of Tele-communications and Defence Establishments are also using solar photo-voltaic systems for their energy requirements; in our country there has been a steady rise in demand for Solar photovoltaic systems. In 1991 it was about 1 M W, in 1992 it rose to 2 MW, in 1993 it was about 4.4 MW and in 1995 the demand for solar photo-voltaic systems rose to 5.6 MWs.
High initial cost of solar photovoltaic modules is the main drawback of the system. However, solar photovoltaic panels require virtually nothing to run and once installed provide energy for years and years together. Therefore these systems are cheaper than other conventional sources of energy. Another major drawback of the solar photovoltaic systems is the non-availability of adequate energy, efficient hardware's required by the system. Storage batteries, inverters, lamps, motors, pumps etc. which can work efficiently on energy provided by solar photovoltaic modules are often difficult to find in the market.
However, sincere efforts are being made to overcome these difficulties as should be apparent from the rise in the demand of solar energy conversion systems. We have been successful in producing silicon modules in sufficient quantity and are currently exporting them to other countries. There has also been a decline in the cost of production of solar photovoltaic modules since its manufacture was undertaken in India.
3. Wind Energy:
Wind energy is another very important, clean and renewable source of energy which is slowly making its presence felt in India. In fact the efforts to use wind energy were started during the Seventh Five-Year Plan period in our country. It was in the year 1983 that wind velocity data from various observatories of Indian Meteorological Department were analyses and published which revealed the enormous wind energy potential of our country. This led the Government to initiate surveys and research. The wind energy potential of our country has now been estimated to be about 20,000 MWs-about one-fifth of our total installed power generation capacity in 1995.
We are now making rapid progress in utilization of wind power. The installed capacity of about 61 MW during the year 1993-94 has now jumped to about 235 MW during the year 1994-95. A total capacity addition of about 18,000 MW is under various stages of development and planning whereas about 80 sites in different states and Union Territories in India have been selected for installation of wind power farms.
4. Biomass Based Energy Resources:
Biomass is general term used for all material originating from photosynthesis. Biomass based energy resources are renewable and cleaner than coal, oil or fuel wood. They can also be used to minimize the pollution caused by organic wastes. All bio-degradable materials when subjected to anaerobic decomposition yield combustible gases, mostly methane (CH4) which is a major constituent of natural gas as well.
In India plenty of cow-dung and other agricultural wastes are available which may be digested an aerobically to produce about 22,500 million cubic metres of methane (commonly called Gobar gas) and about 206 million tons of organic manure every year. Department of Non- conventional Energy Sourches launched a national gobar gas development porgramme under which about 150,000 gobar gas plants were installed in our country during the year 1984-85. It is estimated that these plants can save about 600,000 tons of fire wood every year and satisfy the energy requirement of about 20 million houses in Indian villages.
In India attempts are also being made to identify potential plant species which can serve as a source of liquid petroleum. It is proposed to cultivate such plant species on denuded waste land and use the biomass for extraction of liquid hydrocarbons. Similarly these waste lands can also be used for the cultivation of fast growing plants. The biomass from these plants can be used to supplement our firewood stock. This biomass can also be coverted into coal or coal gas to provide a more convenient form of energy.
5. Other Non-Conventional Sources of Energy:
Proposals for utilization of ocean tidal energy, the energy of ocean waves and geothermal energy are also under consideration in India. Our country has a vast coastline - about 6000 kms and a number of places where we can conveniently harness energy from oceans. Similarly the hilly tracts of Himalayas and hills of Central India have a number of locations suitable for development of geothermal energy. However, the use of these forms of energy is in survey, research and planning stages only.