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. This wind flow, or motion energy, is “harvested” by modern wind turbines and can then be used to generate electricity.
Wind turbines convert the kinetic energy in the wind into mechanical power. These turbines, like aircraft propeller blades, turn in the moving air and power an electric generator that supplies an electric current. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.
Wind turbines are mounted on a tower to capture the most energy. At 100 feet or more aboveground, they can take advantage of the faster and less turbulent wind.
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.
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 differ in power ratings. Utility-scale turbines range in size from 50 to 750 kilowatts. Single small turbines, below 50 kilowatts, are used for homes, telecommunications dishes, or water pumping.
- Wind energy is very abundant in many parts of the United States.
- Wind energy is a free, renewable resource. Wind energy is also a source of clean, non-polluting, electricity. Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases. Additionally, wind turbines can be located on land that is also used for grazing or farming.
- If wind generating systems are compared with fossil-fueled systems on a “life-cycle” cost basis, wind costs are much more competitive with other generating technologies because there is no fuel to purchase and minimal operating expenses.
- Wind power is an intermittent power source and does not always blow when electricity is needed. Wind cannot be stored, and not all winds can be harnessed to meet the timing of electricity demands.
- Good wind sites are often located in remote locations far from areas of electric power demand.
- Wind resource development may compete with other uses for the land, and those alternative uses may be more highly valued than electricity generation.
- The technology requires a higher initial investment than fossil-fueled generators. Roughly 80% of the cost is the machinery, with the balance being site preparation and installation.
The cost of wind power has decreased dramatically in the past 10 years. As a result, wind energy has seen a 30% annual growth rate over the past decade.