Harnessing Wind Energy to Generate Wind Power
Till a few decades back energy in India meant electrical energy generated by employing hydro, thermal and nuclear sources. India is blessed with ample hydro and thermal reserves in form of rivers and one of the world's largest deposits of coal respectively. Since independence large number of dams have been built across rivers all over India beginning with Bhakra Dam in Punjab. Equally there are large number of power houses running on thermal energy released by burning coal. Today huge quantities of higher quality coal are imported from Indonesia and Australia to meet the ever increasing demands from new power stations. Another fuel which has become increasingly available is natural gas which is supplied to power houses for electricity generation.
However there is a free resource available for power generation throughout the world. It is wind energy. Today wind energy is being harnessed to run wind turbines and generate power. In course of time wind power is going to become important as it is also non polluting in nature. Let us examine the various aspects of utilization of wind energy.
Current Power Scenario in india :
The need for electricity exists in all sections of the society ranging from domestic to farming to industry to street lighting etc. Even after 67 years of independence there is a significant unfulfilled demand by consumers all over the country. Only Gujarat claims to have developed a supply scenario where electricity is available on a 24x7 basis to consumers. We are all aware of severe power cuts for a number of hours, in almost all states during the summer months, when demand for power is at its peak. Hydro power stations face severe shortage of water during summer especially if the previous monsoon has been less than normal. Thermal power stations are faced with supply of poor quality coal containing very high percent of ash, which leads to increased cost of power generation. Natural gas is a clean source but its supply is very limited.
Electricity is the prime component in the energy scenario of India. During 2009-10, in normal times the shortage in electric supply vs demand was around 10.1% equivalent to around 83, 950 MW and in peak demand periods the shortage rises to around 13.3%. The power deficit is increasing every year. India's electrical consumption has shown an average rise of 7.3% per year. The demand is highest from the industrial sector followed by domestic, agriculture and commercial consumers. The per capita electricity consumption has increased from 178 kWh in 1985-86 to more than 846 kWh presently, even though it is still low by international standards.
The target set for capacity addition during the 11th Five Year Plan was 78,700 MW, in which thermal power was to contribute 76%, hydro 20% and nuclear 4%. It is estimated that only around 55,000 MW was added compounding the shortages further.
The total installed electricity generation capacity has increased from 16,271 MW in to 2,37,742 MW in February, 2014. It is the fourth largest in the world. This is an average growth rate of around 6.60% per year. The thermal power plants account for 59%, hydro power plants 17%, renewable energy 12%, natural gas for about 9% and nuclear power 2,02% of the installed capacity.
Resources for Power Generation:
As of 31.03.2012, in India the estimated reserves of coal was 294 billion tons, lignite reserves were 42 billion tons, crude oil reserves were 760 million tons and the natural gas reserves were around 1330 billion cubic meters.
The total potential for renewable power generation in the country as on 31.03.12 is estimated at 89,774 MW. This includes wind power potential of 49,130 MW (54.73%), SHP (small-hydro power) potential of 15,399 MW (17.15%), Biomass power potential of 17,538 MW(19.54%) and 5,000 MW (5.57%) from bagasse-based cogeneration in sugar mills.
The renewable power generated and fed into the power grids of the country was 29,500 MW in December, 2013 registering nearly 24% annual growth rates. It consisted of app. 69.65% from wind power, 13.63% from small hydro power and 12.58% from biomass power.
The non-renewable installed power capacity is around 87.55% and renewable power installed capacity is 12.45%.
Wind Power in India :
It is estimated that as of January 31, 2014 the total installed power capacity of non-conventional renewable technologies was 31,150 MW about 13.32% of the total installed capacity. Out of this wind energy accounted for 20,299 MW equivalent to 65% of the installed capacity. India has the fifth largest wind power capacity in the world accounting for nearly 6% of India's total power capacity and 1.6% of its power output.
The development of wind power in India was pioneered by Tamil Nadu Electricity Board in 1990 by setting up a wind farm near Tuticorin. Since then other states like Maharashtra, Gujarat, Karnataka and Rajasthan have taken to installing wind power facilities. Tamil Nadu has a share of nearly 40% in the country's wind power generation.
As of December 31,2013, Tamil Nadu had 7154 MW, Gujarat had 3093 MW, Maharashtra had 2976 MW, Karnataka had 2113 MW, Rajasthan had 2355 MW, MP had 355 MW, AP had 435 MW and Kerala had 35 MW installed wind power capacity. It is planned to add an additional of 6,000 MW by end 2014.
How does a wind turbine generate power ?
It basically captures the energy of the moving air and converts it into electricity. Most turbines have three aerodynamically designed blades over which wind passes creating lift which then causes the rotor to rotate. The rotating blades in turn spin a shaft 30-60 times a minute. This low speed shaft is connected through a gear box to a high speed shaft which is made to rotate at 1000-1800 rotations per minute. This high speed shaft is connected to a generator and it produces power, which goes onto a transformer that converts it into the right voltage for feeding into the electricity grid.
Wind speeds between 4 - 25 meters per second are suitable for producing energy. The turbine is not run if wind speeds exceed 25 meters per second as it can cause damage to it. In general higher wind speeds produce more energy. Larger the blade radius more the power that can be generated. Higher air density exerts more lift on the rotor and is the main reason why wind turbines are located near sea levels rather than at elevations where air is relatively lighter and will produce less power.
Wind Energy Potential :
A 120 meter diameter rotor will produce at on shore location and at 4 meter per second wind speed, 420 MWh power at 0 altitude vs 7134 MWh at 25 meter per second wind speed. Same rotor at offshore location will produce 804 MWh power vs 15280 MWh at 0 altitude. It is estimated that an 1,00,000 MW of wind power can produce same amount of electricity over a year as 62 coal power plants or 39 nuclear plants or 52 gas power plants and meet the consumption of nearly 57 million households. Offshore wind power generation is a developing and challenging opportunity being pursued with vigour because of its higher power generation capabilities. It involves setting up of wind turbines on towers in the sea.
Advantages of Wind Power :
Wind energy is a non polluting way of producing electricity. As no fossil fuel is burned, no carbon dioxide/carbon monoxide and particulate matter is released into the atmosphere. It is thus a green form of electricity. For every kWh of power produced 696 g of CO2 is avoided. Increasingly onshore wind energy is becoming competitive with fossil fuel especially when carbon dioxide disadvantage costs are offset.
Wind does not cost and is available without being controlled by any person or nations unlike fossil fuels.
Global Scenario :
The total installed wind power installed capacity at the end of 2012 was 2,82,482 MW with major installations in Asia and Europe accounting for 73%. China's installed capacity was 75,564 MW largest in the world. USA with 60,000 MW is second and Germany with 31,332 MW and Spain with 22,796 MW are at number three and four. India with 18,421 MW is at number five. The top ten countries account for nearly 86% of the installed capacity.
About 75 countries are generating wind power and 22 of them have crossed 1GW level. The annual growth rate is around 10%. In 2012 US installed 13,124 MW of wind power. China also installed almost same capacity. India installed 2,300 MW capacity. Europe installed nearly 12,000 MW capacity.
In Denmark 26% of electricity demand is met by wind power and is likely to go up to 50% by 2025. Currently the figure is 16% in Spain, 12% in Ireland and 11% in Germany. The European Union power sector is seriously moving away from fuel oil and coal with increased investments in wind energy. Around total of 8% of EU's total power generation will be from wind energy with higher figures by individual countries.
A total of 418 offshore wind turbines were set up in Europe in 2013 capable of generating 1,567 MW of power and raising the total offshore wind power capacity to 6,562 MW. The number of offshore wind turbines is now 2,080 numbers with average capacity being 4 MW.
At the end of 2012,it is estimated that a total of 2,25,000 wind turbines are in operation. Nearly 50,000 of these are installed in China and its growth rate is nearly 40% per year.
Around 2.5% of the global electricity is supplied by wind power and in can go up to 8- 12 % by 2020. It is estimated that 6 MW offshore wind turbine can supply power to 5,500 houses in European Union. A wind turbine has 8,000 parts and the largest wind turbine has a blade diameter of 150.8 meters.
Every year June 15 is celebrated as the Wind Day
Wind Power Challenges ;
Wind power costs between 4-6 cents per kilowatt-hour. Its initial cost is high and transmission costs are also to be incurred as wind turbines are located at remote places. It has to compete with conventional power generation technologies. Although wind power plants have no impact on the environment but the rotor noise is a cause of concern. Also the environmental aesthetics can be aissue if these are to be located near to cities or towns. Some times birds get killed because of the rotors.
Some of the major companies involved in wind turbine manufacture are GE Wind, Enercon, Gamesa, Vestaa and Suzlon. Chinese manufacturers are giving severe competition to German companies.
Wind power capacity should grow by leaps and bounds in India. It has a very long coast line and both on shore and offshore wind turbines can be erected. India has to import more than 70% of its fuel requirements and quality of coal is also not good necessitating import of coal to run power stations. Hydro power capacity is almost achieved and there is resistance to new dams.
Renewable energy sources like wind, solar, tidal and biomass will be increasingly utilized. Of these the most widely employed is wind energy. That a large number of countries are involved in its use and development shows its potential. India is today has the fifth largest capacity and if China is a reference than India has lot of potential to catch up. This non polluting energy source can over a period of say five decades contribute nearly 25% of our electricity needs. Together with solar energy, wind energy can ba major raw materials to generate electricity in India in the near and distant future.
India's wind god Maruti's blessings are always available.
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