ABSTRACT
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. Turbine components: Horizontal turbine components include: 1. Blade or rotor, which converts the energy in the wind to rotational
shaft energy. 2. A drive train, usually including a gearbox and a generator. 3. A tower that supports the rotor and drive train. 4. Other equipment, including controls, electrical cables, ground support
equipment, and interconnection equipment. Wind turbines are often grouped together into a single wind power plant, also known as a wind farm, and generate bulk electrical power. Electricity from these turbines is fed into a utility grid and distributed to customers, just as with conventional power plants. Wind turbines are available in a variety of sizes, and therefore power ratings. The largest machine has blades that span more than the length of a football field, stands 20 building stories high, and produces enough electricity to power 1400 homes. A small home-sized wind machine has rotors between 8 and 25 ft in diameter and stands upwards of 30 ft and can supply the power needs of an all-electric home or small business. Utility-scale turbines range in size from 50 to 750 kW. Single small turbines, below 50 kW, are used for homes, telecommunications dishes or water pumping. A renewable non-polluting resource: Wind energy is a free, renewable resource, so no matter how much is used today, there will still be the same supply in the future. Wind energy is also a source of clean, non-polluting, electricity. Cost issues: The technology requires a higher initial investment than fossil-fuelled generators. Roughly 80 per cent of the cost is the machinery, with the balance being site preparation and installation. If wind generating systems are compared with fossil-fuelled systems on a ‘life-cycle’ cost basis (counting fuel and operating expenses for the life of the generator), however, wind costs are much more competitive with other generating technologies because there is no fuel to purchase and minimal operating expenses. Environmental concerns: Although wind power plants have relatively little impact on the environment compared to fossil fuel power plants, there is some concern over the noise produced by the rotor blades, aesthetic (visual) impacts, and birds and bats having been killed (avian/bat mortality) by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly citing wind plants.
