Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. The earth’s surface is made of different types of land and water. These surfaces absorb the sun’s heat at different rates, giving rise to the differences in temperature and subsequently to winds. During the day, the air above the land heats up more quickly than the air over water. The warm air over the land expands and rises, and the heavier, cooler air rushes in to take its place, creating winds. At night, the winds are reversed because the air cools more rapidly over land than over water. In the same way, the large atmospheric winds that circle the earth are created because the land near the earth's equator is heated more by the sun than the land near the North and South Poles. Humans use this wind flow for many purposes: sailing boats, pumping water, grinding mills and also generating electricity. Wind turbines convert the kinetic energy of the moving wind into electricity.
Wind Energy for power generation
Wind Energy, like solar is a free energy resource. But is much intermittent than solar. Wind speeds may vary within minutes and affect the power generation and in cases of high speeds- may result in overloading of generator. Energy from the wind can be tapped using turbines.
Setting up of these turbines needs little research before being established. Be it a small wind turbine on a house, a commercial wind farm or any offshore installation, all of them, at first, need the Wind Resource to be determined in the area of proposed site. The Wind Resource data is an estimation of average and peak wind speeds at a location based on various meteorological. The next step is to determine access to the transmission lines or nearest control centre where the power generated from the turbines can be conditioned, refined, stored or transmitted. It is also necessary to survey the impact of putting up wind turbines on the community and wildlife in the locality. If sufficient wind resources are found, the developer will secure land leases from property owners, obtain the necessary permits and financing; purchase and install wind turbines. The completed facility is often sold to an independent operator called an independent power producer (IPP) who generates electricity to sell to the local utility, although some utilities own and operate wind farms directly. Wind mills can be set up ranging scales of:
- On-shore grid connected Wind Turbine systems
- Off-shore Wind turbine systems
- Small Wind and Hybrid Energy Decentralized systems (Floating)
- Can be used for both distributed generation or grid interactive power generation using on-shore or off shore technologies.
- Ranges of power producing turbines are available. Micro-turbines are capable of producing 300W to 1MW and large wind turbines have typical size of 35kW-3MW.
- Wind turbine is suitable to install in remote rural area, water pumping and grinding mills
- Average capacity factor can be close or higher than 30%
- The total cost can be cheaper than solar system but more expensive than hydro.
- Electricity production depends on- wind speed, location, season and air temperature. Hence various monitoring systems are needed and may cost expensive.
- High percentage of the hardware cost (for large WT) is mostly spent on the tower designed to support the turbine
The range of wind speeds that are usable by a particular wind turbine for electricity generation is called productive wind speed. The power available from wind is proportional to cube of the wind's speed. So as the speed of the wind falls, the amount of energy that can be got from it falls very rapidly. On the other hand, as the wind speed rises, so the amount of energy in it rises very rapidly; very high wind speeds can overload a turbine. Productive wind speeds will range between 4 m/sec to 35 m/sec. The minimum prescribed speed for optimal performance of large scale wind farms is about 6 m/s. Wind power potential is mostly assessed assuming 1% of land availability for wind farms required @12 ha/MW in sites having wind power density exceeding 200 W/sq.m. at 50 m hub-height.
The energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of faster and less turbulent wind. Wind turbines can be used to produce electricity for a single home or building, or they can be connected to an electricity grid (shown here) for more widespread electricity distribution. Furthermore projects are going on exploring in Research Design and Development to achieve following goals:
- Continue cost reduction: improved site assessment, better modeling for aerodynamics, intelligent/recyclable materials, stand-alone and hybrid systems.
- Increase value and reduce uncertainties: forecasting power performance, improving standards and engineering integrity and storage techniques.
- Enable large-scale use: Load flow control and adaptive power quality
- Minimize environmental impacts: Noise impacts, Flora and Fauna, utilization of land resources and aesthetics integration
India‘s Unique Proposition
Geographic Location and Wind Potential: The potential is far from exhausted. It is estimated that with the current level of technology, the ‘on-shore’ potential for utilization of wind energy for electricity generation is of the order of 65,000 MW. India also is blessed with 7517km of coastline and its territorial waters extend up to 12 nautical miles into the sea. The unexploited resource availability has the potential to sustain the growth of wind energy sector in India in the years to come. Potential areas can be identified on Indian map using Wind Power Density map. C-WET, one of pioneering Wind Research organization in the country is leading in all such resource studies and has launched its Wind Resource map.
In a step towards identifying and properly exploiting these wind resources, MNRE has estimated state-wise wind power potential in the country.
- World Market Share: According to REN21- Global Status Report 2011 (GSR-2011), Indian company Suzlon was among top ten manufacturers of Wind Turbine manufacturer’s in the world with world market share of 6.7%. Also major world companies are pouring into the fast evolving Wind Energy market in India: Vestas, GE Wind, Enercon and Gamesa have already opened up their establishments across various cities in India.
- Government Support and Policies: Several states have come up with renewable energy policies like Karnataka, Tamil Nadu and Andhra Pradesh. More details of and summary for such policies is available on this page.
Installed Capacity: According to MNRE ‘s achievent report, The cumulative installed capacity of Grid Interactive Wind Energy in India by the end of September 2011 was 14989MW (of which 833MW was installed during 2011-2012 against a target of 2400MW). Aerogenerators and hybrid systems contributed 1.20MW during 2011-12 to yield cumulative off-grid wind capacity of 15.55MW.
India in the windy world: In 2008, India shared 6.58% of total wind energy installed capacity around the world, according to World Wind Energy Report-2008. According to GSR-2011, the world witnessed highest renewable energy installations through wind energy. Total installed capacity of wind energy reached 198GW by the end of 2010. India ranked third in the world in annual capacity additions and fifth in terms of total wind energy installed capacity. India has been able to fast pace its growth in wind energy installations and bring down costs of power production. The GSR 2011 reported on-shore wind power (1.5-3.5MW; Rotor diameter 60-100m) at 5-9 cents/kWh and off shore wind power (1.5-5MW; Rotor diameter 75-120m) at 10-20 cents/kWh. But India’s onshore wind power cost reached 6-9cents/kWh in 2008 itself (Indian Renewable Energy Status Report-2010).
Clean Wind to overcome power shortage: Electricity losses in India during transmission and distribution have been extremely high over the years and this reached a worst proportion of about 24.7% during 2010-11. India is in a pressing need to tide over a peak power shortfall of 13% by reducing losses due to theft. Theft of electricity, common in most parts of urban India, amounts to 1.5% of India’s GDP. Due to shortage of electricity, power cuts are common throughout India and this has adversely affected the country’s economic growth. Hence a cheaper, non-polluting and environment friendly solution to power rural India is needed.
Wind energy as job generator: Wind energy utilization creates many more jobs than centralized, non-renewable energy sources. Wind Energy companies have opened up huge career options. Also the ease and accessibility of manufacturing technology has given entrepreneurs with new business options to venture in. The wind sector worldwide has become a major job generator: Within only three years, the wind sector worldwide almost doubled the number of jobs from 235,000 in 2005 to 440,000 in the year 2008. These highly skilled employees are contributing to the generation of 260 TWh of electricity.
A notable feature of the Indian programme has been the interest among private investors/developers in setting up of commercial wind power projects. Several companies have established themselves in wind technology manufacturing. The gross potential is 48,561 MW (source C-wet) and a total of about 14,158.00 MW of commercial projects have been established until March 31, 2011. All projects installed in India are listed on this page. The break-up of projects implemented in prominent wind potential states (as on March 31, 2011) is as given below:
|State||Gross Potential (MW)||Total Capacity (MW) till 31.03.2011|
Two Wind POwer summarized cae studies centered around State and company are: