Wind turbines, like aircraft propeller blades, turn in the moving air and power an electric generator that supplies an electric current. Simply stated, a wind turbine is the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.
Wind Turbine Types
Modern wind turbines fall into two basic groups; the horizontal-axis variety, like the traditional farm windmills used for pumping water, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor. Most large modern wind turbines are horizontal-axis turbines.
Horizontal turbine components include:
blade or rotor, which converts the energy in the wind to rotational shaft energy;
a drive train, usually including a gearbox and a generator;
a tower that supports the rotor and drive train; and
other equipment, including controls, electrical cables, ground support equipment, and interconnection equipment.
Power generation from wind has emerged as one of the most rapidly growing renewable energy technologies. The estimated power generation capacity in India through wind is about 45,000 MW. The installed capacity is about 1,870 MW, which is about 4% of the total estimated potential.
Globally, wind generation capacity has increased by 27% in the year 2002 and is expected to expand 15 – fold in the next 20 years. Wind energy technologies have matured and large capacity wind turbines in the range of 1.25 to 1.65 MW are now being manufactured in India. The productivity of larger capacity machines is higher than that of smaller machines. Minimum wind velocity required for power generation is about 2.5 m/s and the maximum could be 30 m/s.
Energy generation for 1 MW turbine could be about 28 to 30 lakhs units per year, with a plant load factor of 25 to 30% Among the different renewable energy sources, wind energy is currently making a significant contribution to the installed capacity of power generation, and is emerging as a competitive option. The programme covers research and development, survey and assessment of wind resources, implementation of demonstration and private sector projects and promotional policies. As a result, India, with an installed capacity of about 3000 MW, ranks fifth in the world after Germany, USA, Spain and Denmark in wind power generation.
Small wind energy systems, namely water pumping windmills, aero generators and wind-solar hybrid systems can also be used for harnessing wind power potential, in addition to the large capacity wind turbines. These systems have been found to be very useful for meeting water pumping and small power requirements in decentralised mode in rural and remote windy areas of the country, which are un-electrified or have intermittent electric supply.