19-01-2016, 02:30 PM
Introduction
The Industrial Revolution of the 19th century ushered in new technologies. The spurt in inventions in that century was unprecedented in many ways. Some of these inventions involved use of natural resources like coal and oil. The thought of exhaustible nature of these resources and the environmental damage from the use of these resources never occurred either to the inventors or the subsequent generations. In the quest to sustain galloping economic activity, the dependence on coal and oil has soared at a phenomenal rate over the years. The burnt fuels result in the release of carbondioxide and other gases into the atmosphere causing environmental damage. It has become imperative to look at energy technology with a new perspective. There are abundant renewable sources of energy such as wind, sun, water, sea, biomass apart from even daily wastes. These sources are pollution free and hence clean energy apart from being unlimited/ inexhaustible.
Power generation in India has grown in size to around 1 lakh MW and in Tamil Nadu it has increased to 7924 MW which is distributed through a vast network of transmission, sub-transmission and distribution lines that reach all villages even in remote areas. The demand for power is growing rapidly. The problem will be compounded due to fast depletion of fossil fuel deposits, quality of fuels, heavy price to be paid for basic materials plus their transportation cost and above all the environmental degradation caused by the use of conventional energy sources. Under such conditions, environment-friendly and pollution-free, non-conventional and renewable energy sources known as 'clean and green energy' have emerged as an important alternatives to conventional energy sources. The renewable energy sources are clean and inexhaustible as they rely on sun, wind, biomass, etc., as primary sources of energy. It is estimated that, about 2000 MW can be generated from wind potential available in Tamil Nadu. As against this potential, 19 MW of power in the State Sector mostly through demonstration wind farms and 838 MW in the private sector have been harnessed as on 31.3.02, Under Biomass, the estimated potential is about 500 MW and 154 MW capacity has been expected using biomass/bagasse.
The country is endowed with large amount of sustainable resource base and non-conventional energy technologies which are well-suited for grid connected power generation, energy supplies in remote areas which are not/ could not be connected to the grid and for captive consumption. Non-conventional energy sources like wind energy, solar energy through thermal as well as photovoltaic system, biomass and hybrid sources will help to a great extent in enhancing power generation capacity. Hence appropriate policies and programmes that optimise the use of available energy resources with new technologies have to be propagated, promoted and adopted, if necessary, by budgetary support.
Tamil Nadu has done very well in promoting and harnessing renewable sources of energy particularly wind and bagasse based power generation. With a view to develop and propagate the non-conventional sources of energy, the Tamilnadu Energy Development Agency (TEDA) was formed in 1985. Apart from serving as a coordinating agency to promote the use of non conventional energy sources, TEDA acts as nodal agency to the Ministry of Non-conventional Energy Sources (MNES), Government of India to implement Centrally funded and sponsored schemes in the State. During the past 17 years, TEDA has conducted sustained campaigns to promote harnessing of renewable energy with active support from the Central and the State Governments. The total installed capacity in Tamilnadu under Non-conventional Energy Sources is 1000 MW as on 31.3.2002 which is about 13% of total TNEB grid capacity, while at the All-India level, it is only 3%. The major share of this comes from Wind Energy followed by bagasse based co-generation plants in sugar industries. This has largely come through private investments encouraged by policy initiatives of the Central and the State Governments.
Non - Conventional or Renewable Energy Sources
1.Wind Energy
The evolution of windmills into wind turbines did not happen overnight and attempts to produce electricity with windmills date back to the beginning of the century. It was Denmark which erected the first batch of steel windmills specially built for generation of electricity. After World War II, the development of wind turbines was totally hampered due to the installation of massive conventional power stations using fossil fuels available at low cost. But the oil crisis of 1973 heralded a definite break through in harnessing wind energy. Many European countries started pursuing the development of wind turbine technology seriously and their development efforts are continuing even today. The technology involves generation of electricity using turbines, which converts mechanical energy created by the rotation of blades into electrical energy, some times the mechanical energy from the mills is directly used for pumping water from well also. The wind power programme in India was started during 1983-84 with the efforts of the Ministry of Non-Conventional Energy Sources. In India the total installed capacity from wind mills is 1612 MW, of which, Tamilnadu has an installed capacity of 858 MW as on 31.03.2002.
Tamil Nadu is endowed with lengthy mountain ranges on its Western side with three prominent passes in its length. These are with wind-potentials: (1) Palghat Pass in Coimbatore District-1200 MW, (2) Shengottah Pass in Tirunelveli District-500MW and (3) Aralvoymozhi Pass in Kanniyakumari District- 300 MW (Total potential-2000 MW). The mountainous areas close to Cumbum Valley are observed to be having high potential and, though coastal areas, central plains and hilly areas have been observed unsuitable for wind power projects, Rameshwaram is found suitable.
2.Bio Energy
Biomass is yet another important source of energy with potential to generate power to the extent of more than 50% of the country's requirements. India is predominantly an agricultural economy, with huge quantity of biomass available in the form of husk, straw, shells of coconuts wild bushes etc. With an estimated production of 350 million tons of agricultural waste every year, biomass is capable of supplementing coal to the tune of about 200 million tonnes producing 17,000 MW of power and resulting in a saving of about Rs.20,000 crores every year. Biomass available in India comprises of rice husk, rice straw, bagasse, coconut shell, jute, cotton, husk etc. Biomass can be obtained by raising energy farms or may be obtained from organic waste. The biomass resources including large quantities of cattle dung can be used in bio-energy technologies viz., biogas, gasifier, biomass combustion, co-generation etc., to produce energy-thermal or electricity. Biomass can be used in three ways - one in the form of gas through gasifiers for thermal applications, second in the form of methane gas to run gas engines and produce power and the third through combustion to produce steam and thereby power.
3.Solar Energy
Solar Power was once considered, like nuclear power, 'too cheap to meter' but this proved illusory because of the high cost of photovoltaic cells and due to limited demand. Experts however believe that with mass production and improvement in technology, the unit price would drop and this would make it attractive for the consumers in relation to thermal or hydel power. The Solar Photo Voltaic (SPV) technology which enables the direct conversion of sun light into electricity can be used to run pumps, lights, refrigerators, TV sets, etc., and it has several distinct advantages, since it does not have moving parts, produces no noise or pollution, requires very little maintenance and can be installed anywhere. These advantages make them an ideal power source for use especially in remote and isolated areas which are not served by conventional electricity making use of ample sunshine available in India, for nearly 300 days in a year.
A Solar Thermal Device, on the other hand captures and transfers the heat energy available in solar radiation. The energy generated can be used for thermal applications in different temperature ranges. The heat can be used directly or further converted into mechanical or electrical energy.
4.Other Sources
The other sources of renewable energy are geothermal, ocean, hydrogen and fuel cells. These have immense energy potential, though tapping this potential for power generation and other applications calls for development of suitable technologies.
(i) Geo-Thermal Energy
Geo-Thermal energy is a renewable heat energy from underneath the earth. Heat is brought to near surface by thermal conduction and by intrusion into the earth's crust. It can be utilised for power generation and direct heat applications. Potential sites for geo-thermal power generation have been identified mainly in central and northern regions of the country. Suitable technologies are under development to make its exploitation viable.
(ii) Ocean thermal and Tidal energy
The vast potential of energy of the seas and oceans which cover about three fourth of our planet, can make a significant contribution to meet the energy needs. Ocean contains energy in the form of temperature gradients, waves and tides and ocean current, which can be used to generate electricity in an environment-friendly manner. Technologies to harness tidal power, wave power and ocean thermal energy are being developed, to make it commercially viable.
(iii) Hydrogen and Fuel Cells
In both Hydrogen and Fuel Cells electricity is produced through an electro-chemical reaction between hydrogen and oxygen gases. The fuel cells are efficient, compact and reliable for automotive applications. Hydrogen gas is the primary fuel for fuel cells also. Hydrogen can be produced from the electrolysis of water using solar energy. It can also be extracted from sewage gas, natural gas, naptha or biogas. Fuel cells can be very widely used once they become commercially viable.
(iv) Bio fuels
In view of worldwide demand for energy and concern for environmental safety there is need to search for alternatives to petrol and diesel for use in automobiles. The Government of India has now permitted the use of 5% ethanol blended petrol. Tamilnadu is one of the nine States in the country where this programme will commence from January 2003. Ethanol produced from molasses/ cane juice, when used as fuel will reduce the dependence on crude oil and help contain pollution. Further, technology is also being developed to convert different vegetable oils especially non-edible oils as bio-diesel for use in the transport sector. They are however, in R & D stage only.
5. Potential and Exploitation of Renewable Energy Sources
India ranks fifth in the world in Wind power with installed capacity of 1612 MW out of an estimated potential of 45,000 MW. Tamilnadu ranks first in the country in Wind power with a capacity of 858 MW out of an estimated potential of 3050 MW. In biomass power the country has an installed capacity of 381 MW out of total potential of 19500 MW. In Tamilnadu the installed capacity is 142 MW against the potential of 1000 MW. The potential available under solar photovoltaic energy is 20 MW per Sq.Km. But in view of high cost and heavy investment involved the progress is rather slow.In Solar thermal energy (Solar Water Heater system) 15 lakh M2 collector area has been installed in the country against a potential of 1400 lakh M2. In Tamilnadu, 20084 M2 area has been installed. There is considerable scope for expanding this activity with suitable incentives.The most note-worthy achievement of Tamilnadu has been in creating an installed capacity of about 1000 MW from the non-conventional energy sources alone in the State, i.e., 13% of the total TNEB grid capacity against 3.2% only for the country. The major component of this has come from Wind Energy (858 MW) followed by co-generation in sugar industries (142 MW). Further, this has largely come about through private investment due to attractive policy initiatives of the State and Central Governments. It may be worthwhile to offer various incentives to enhance its share further in view of the vast potential available.