Energy in the form of electricity is critical for economic growth, social development and human welfare. In this materialistic world the status of a country is adjudged by its per capita consumption of electricity. That way our per capita consumption of 350 kWh per Anum may be ten times less in comparison to the United States and proves us to be a poor and undeveloped country. This may not be true as the living habits of our major countrymen i.e. the rural masses are totally different.
They live closure to nature and by their age-old practices they utilize the energy gifted by nature in a more natural way. This was true when India lived in villages but now the pattern is changing. 11% of our population living in cities in the year 1901 has become 26% in 1991. This urbanization has changed our living style and we are also in the race of consuming more and more energy even at the cost of environmental degradation. India with its present installed capacity of 1,30,000 MW is facing a 10% deficit per year, which results in a loss of production of about 2% of the national income.
All of us are aware of the power cuts for most of the times in a year. But the question is this that where this present system of energy conversion and utilization will lead us? At present the electricity production in India is roughly 68% by coal and other fossil fuels, 22% by hydro power, 4% by nuclear and only 6% by renewable energy sources, though there is a large scope for it. The present installation cost of electric plant based on fossil fuel is about Rs. 5 crore per MW and that by solar photovoltaic may be Rs. 200 per watt i.e. 20 crores per MW. But this type of comparison is unfortunate. All of us know that the fossil fuels are not everlasting.
They are depleting at a very fast rate, and the main thing is the pollution caused by them. The pollution in terms of suspended particulate matter (S.P.M.) in the air of Kota was found to be on average 1000 micro gram per cubic meter. Water which is the second biggest need of survival has become so much polluted that the government has to spend 10 times of the money on its purification than the revenue realization. Still a large portion of our rural masses is deprived of electricity and safe drinking water and the urban population is facing the pollution problem
DIFFERENT RENEWABLE SOURCES OF ENERGY
Sun is the prime source of energy. Sun daily spreads an enormous amount of energy; out of which our mother earth receives a very small fraction. Even that small fraction is so much that is sufficient to meet all our demands. The energy that is directly received through the solar radiation can be classified as solar photovoltaic and solar thermal. The word PV means “voltage from light”. The photovoltaic cells are used to turn sunlight directly into electricity. PV cells generate power through the interaction of tiny particles of light called “photons” with electrons in the cells.
PV cells were originally developed for use in space program, PV cells have powered nearly every man-made satellite sent into the orbit. These days many equipment is using solar energy in this way and so many buildings are being equipped with arrays of PV cells for meeting their electricity demand. In this way of solar energy conversion by photovoltaic means the semiconductor silicon cells directly convert the sun’s light into electricity. But the efficiency is very low and the cost is high because of the problem of very high requirements of purity of material.
The material should be almost cent per cent pure. For small applications the cost may be as high as Rs. 3 lakh per kW. One solar photovoltaic pump of 1 H.P. costing Rs. 2.5 lakh is successfully running at Engineering College Kota under the Renewable Energy Park Project funded by M.N.E.S, installed by R.E.D.A. with author as the principal investigator. Though costly but the PV method of solar energy conversion is very much suitable for decentralized small uses like remote village electrification etc. The PV cells are modular in nature, having long effective life, with no moving parts and no pollution. But the problem of storage in lead acid batteries is typical.
However, on the basis of domestic R & D India has become the second largest manufacturer in the world of solar photovoltaic panel based on crystalline silicon solar cells. Advanced countries are working to install thin PV sheets having very large area in the geo-synchronous orbit of the earth so that they can continuously generate electricity and send it to the earth in the form of microwaves.
Since long time windmills are used to mill wheat and pump water. Modern windmills are called wind turbines. They transform the energy in the wind into mechanical power, which can then be used to produce electricity. Wind turbines can be used singly or in clusters called wind farms and are usually about 60 m high. Small wind turbines called wind chargers are used to charge batteries and can be used by unelectrified homes, boats etc., to power television and other domestic appliances and so on.
For the economical harnessing of wind power a wind velocity of about 7 m/sec. is required which is the major limitation of this system. However, the conversion of wind energy into electricity has increased to 6315 (1/1/07) MW which is more than half of the total production by renewable. It is under sincere considerations even in Rajasthan. 2 MW wind project started in Jaisalmer on 14th August 1999. Rajasthan State Power Corporation Ltd. Plans to construct a new 1-billion rupee 25 MW Wind farm in the district of Jaisalmer. The development is one of the 28 planned state government wind projects expected to generate a total of 444.25 MW of electricity.
As per the officials the state government is also considering other sites at Devgarh, Harhnath, Jaisalmer, kohdal, Mohangarh and Phalodi for the potential establishment of wind farms by private developments.
Energy from Water 111
Hydro power generation is a conventional renewable energy resource utilization method that is most environmental friendly but the problem of rehabilitation is typical. The uncertainty of rainfall and regional problems of water use and distribution are never ending. The ambitious river inter-linking project is yet to be tested .Mini and micro power plants can help in solving the problem. Small hydro Power (up to 25 MW),included in the category of renewable has a large share in the total achievement.
Energy from Oceans
Ocean is also a source of renewable energy. It can be harnessed in three ways. First is the ocean thermal energy conversion method. The temperature difference of about 25° C between the upper layer of water and a layer 1000 m below can be used in a heat engine to produce electric power. Tides can be used as a source of energy from the oceans. Large structures like barrages can be built which allow tidal water to pass through large turbines for producing power. The third way of harnessing energy is the use of sea waves. In India it is generally felt that only tidal energy can be harnessed in the foreseeable future.
Energy from Biomass
Trees and other vegetation convert the sun’s energy directly into the useful biomass. The biomass can be converted into bio gas or bio-liquid ( bio- diesel) and used as a source of energy. Using the wood and other agriculture waste directly by burning is the most inefficient way of energy conversion. By converting it into bio gas at least 25% more energy can be obtained along with the benefit of useful natural organic manure. Biomass is derived from the carbonaceous waste of various natural and human activities. Is obtained from numerous sources including the household waste. Biomass does not add CO2 to the atmosphere because it absorbs the same amount of carbon in growing as it releases when consumed as a fuel.
Unlike other renewable energy systems that require costly advanced technology, biomass can generate electricity with the same equipment/ power plant that are burning fossil fuels at present. In the biological conversion method biomass is converted into bio-gas by anaerobic decomposition method. The raw material may be cattle dung or the organic part of the municipal solid waste. Sometimes the use of other biomass like Water Hyacinth (Jal Kumbhi) helps in the reduction of flow hazards produced by it in the water bodies.
In a study made in the engineering college Kota in which water hyacinth was taken from the local reservoirs and used as the biomass for bio-gas production, it was observed that it could be used efficiently to produce bio-gas. So in the communities where cattle dung is scarce and water hyacinth is available in plenty it serve both purposes of water hyacinth eradication and bio-gas production.
The core of earth is very hot. It is possible to make use of this geothermal energy. In some countries such as the U.S., hot water is pumped from underground water deposits and used to heat the residences.