INTRODUCTION

Society in general has become aware about the conservation of resources and protection of environment. Though the awareness has come after a great loss to the environment in the form of global warming, acid rain and ozone depletion etc. The environmental degradation cannot be dealt within isolation. It has close relation with energy obviously the clean energy, green energy. The energy resources that we are using conventionally like coal and other fossil fuels, have come to the present state in millions of years. We have used them for thousands of years and they are going to be depleted in hundreds of years.  So they are non-renewable, we call them renewable if they can be replenished within the average lifecycle of human being. Renewable energy is the energy that will never end (Akshaya urja shroat). It can be conveniently used to produce electricity and heat we need in our homes, schools, offices, factories etc. In India and all over the world, more and more people are using renewable energy, as it is a very good way of safeguarding our environment. They are less harmful than other kinds of energy sources such as coal, oil and gas (fossil fuels). Fossil fuels are limited in nature and they produce harmful greenhouse gases resulting in global warming. They also produce oxides of nitrogen and sulfur that cause acid rain and various diseases.

Actually, the environment i.e. the living conditions in which we live, play a very important role in the efficient working. But in place of comfortable living the time has come that the very existence of life on our planet is endangered because of the environmental pollution. Exponentially increasing population, rapid growth of industrialization and the global trend of urbanization have totally disturbed the Eco- balance. This type of development cannot be sustained for a long time and the policy planners have to seriously think over it. The discussion in this paper is intended to consider the scope of using renewable energy resources to meet the ever-increasing demand of electricity.

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 annum 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 hydropower, 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 microgram 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.

Is this the sustainable development? Can it be sustained for all times to come? It is neither sustainable nor holistic development. Sustainable development is a term that emerged from the 1992 Earth Summit in Rio de Janerio. Sustainable Development enjoins upon the world community to manage development in such a way that generations are not deprived of the benefits of the planet’s resources particularly its life supporting systems, land, forests, air, water and the oceans. The concept is “to meet the needs of the present without compromising the ability of future generations to meet their  needs”.

Sustainable development can only be achieved if a close link between environment and over-arching agenda for poverty eradication and development is achieved at the earliest. In this context one may be Eco-centric or techno-centric. A middle path, obviously, is desired state as development at the cost of environment can only be at the peril of mankind and such development cannot be sustained .

RENEWABLE SOURCES OF ENERGY

The renewable sources of energy dealt here are solar energy, wind energy, energy from water, energy from the oceans, energy from biomass and the geothermal energy.

• Solar 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 are 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.

The other way of harnessing the solar energy is by solar thermal means. In this method sunray’s heat energy is used either for air, water heating or for the production of electricity. In the later case some parabolic dish concentrates the rays or other deflectors to some fluid like oil and this stored heat is converted to electricity by turbines. At the solar energy center at Gualpahari near Gurgaon electricity is being produced by this method. The Rajasthan State Power Corporation Limited is going to install a 140 MW integrated  combined  cycle  project  having  35  MW  solar  component,  at  Mathania  in Jodhpur district. It will be a solar chimney based power plant where heated fluid will be air. In this method the sunrays are passed through some glass cover, which has the property of allowing sun’s short wave radiation and entrapping the heat of long wave radiation. Thus the temperature inside a collector can be increased to a very high level that can be used for heating air or water for conversion into electricity or solar cooking, solar drying, solar water heating or space heating for comfort in buildings.

A large portion of energy is used in the building industry, in manufacturing the building materials and in space cooling and heating. Domestic and building sector accounts for an average of 45% of the developing countries total energy consumption. Just as in Europe, America and the rest of world where temperature remain below freezing point in winter, scientific and technological advancements have made things easier for people of Ladakh. Solar buildings are now being constructed in the region to fight chill. Ladakh is cold and semi arid, where temperatures vary between –300C and  –60°C  in  winter.

Ladakh  Environment  and  Health  Organization (LEHO)  have introduced solar buildings in Ladakh. The passive solar heated building admits solar radiation through glass and stores it in a dense material-thermal mass-,which can then release the heat slowly. The temperature inside the building remains 15 to 25°C depending upon the glazing, insulation and availability of radiation. This reduces the heating requirement of the building and thus saves electricity.

The following photographs show the photovoltaic cell modules and solar water heaters

• Wind Energy

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 renewables. 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.

The following photograph shows the wind farm (a collection of aerogenerators for the production of electricity).

• Energy from Water

Hydropower 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 renewables has a large share in the total achievement. The following photograph shows a dam for a hydroelectricity power plant.

• 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 biogas 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 biogas at least 25% more energy can be obtained alongwith 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 biogas 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 biogas production, it was observed that it could be used efficiently to produce biogas. 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  biogas  production.

Even human excreta can produce biogas. Aryan society for environmental research and Development, Jaipur has installed a night soil based biogas plant at the police lines Udaipur and at the bus stand in Nathdwara. In the thermochemical use of biomass the various crop residue like rice husk can be burnt in boilers or pallets can be made and electricity may be generated in the power plants. These methods not only help directly in the electricity production but also help in reducing the waste management problem.

• Geothermal Energy

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.

• POTENTIAL OF RENEWABLE ENERGY RESOURCES IN INDIA.

India’s so far assessed potential of wind power is 45000 MW, small hydro power 15000 MW, biomass power 21000 MW (including bagasse cogeneration) and energy recovery from waste is 2700 MW (9) i.e. the total is 83700 MW. Out of this the achievement upto 31.12.2006  is 9265.31 MW. The complete status is as shown in the table.

Table Renewable Energy at a Glance in India

Source ‘Renewable Energy’, ‘Akshaya Urja’ Volume 3 issue1 Jan-Feb 2007 Ministery of New and Renewable Energy Government of India.

• CONCLUSION

There  is  an  acute  necessity  of  switching  over  to  the  renewable  energy  resources, as they are ever lasting, environment friendly and thus sustainable. The present conventional sources of energy are fastely depleting and are not eco-friendly. While comparing the costs of electricity production by coal, oil etc. with the solar, wind etc, the overall environmental cost and their decentralized nature, which stops the migration of rural masses should be considered. The present higher rate of electricity production is because of the developing stage of renewable energy sources. The increasing R & D, and the utilization of RES on mass scale will certainly bring them at par. Large potential of renewable energy resources is available. Capacity building of individuals and organizations; proportionate investments in renewable energy technologies, production facilities, market infrastructure and human resource development are all required for a rapid growth of the global RE market. The lack of awareness alongwith the lack of both senior and middle level local technical manpower is proving to be the biggest barriers at present. Awareness, education and training unlock human potential and can be powerful force to shape positive social and economical development around the world. In the renewable energy field all modes of education are therefore of prime importance, especially about the use and  potential  of  RE  technologies,  in  all  teaching  institutes.  Additionally  industry non-government and voluntary organizations and society at large need to get involved in this initiative to make renewable energy education/  capacity building a  people  oriented  program.

• Written by Lohit Seth.
• In category Arts & Science.
• 14 years ago.

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