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For over 1,300 years, humans have used windmills to convert the power of the wind to mechanical energy. In contrast to early windmills, modern wind turbines utilize generators and other components to transform the energy generated by the spinning blades into a steady flow of alternating current electricity.
FREMONT, CA: Wind energy accounts for a tiny but growing share of electricity generation. It generates 5 percent of worldwide electricity production and 7 percent of the United States' electrical supply.
Wind energy worldwide exceeds 651 gigawatts, which is greater than grid-connected solar energy and around half of what hydropower can offer. Wind farms generate almost three-quarters of the 651 gigawatts in five countries: China, the United States, Germany, India, and Spain. Wind energy capacity has tripled across the Americas over the last decade.
Currently, the United States has more wind turbines than it needs to generate 100 million watts of electricity, or around 29 million megawatts, which is enough to power all of the country's average homes.
Wind energy's cost has decreased dramatically during the last decade. In the US, it is cost-competitive with natural gas and solar energy.
Wind and solar energy are complementary, as wind is frequently highest after the sun has heated the ground for a while. Warm air rises from the hottest locations, creating a vacuum into which other air can rush, resulting in horizontal wind currents. Wind energy is advantageous in places that are overcast or dark to generate significant amounts of solar energy, particularly at higher latitudes. People can use solar energy throughout the day and wind energy at night and in the evening.
Typical utility-scale land-based wind turbines are approximately 250 feet tall and have an average capacity of 2.55 megawatts, capable of powering hundreds of homes. While land-based wind farms are sometimes in distant locations, most of them are easily accessible and connect to existing electricity infrastructures.
Smaller turbines, frequently used in distributed systems that generate electricity for local use rather than sale, stand on average around 100 feet tall and generate between 5 and 100 kilowatts.
While tall offshore wind turbines lack some of the advantages of land-based wind farms, their use is increasing due to their ability to harness the energy of strong, dependable winds high in the air near coasts, which are home to the majority of the world's largest cities. One type of offshore wind turbine now under development stands 853 feet tall, or four-fifths the height of the Eiffel Tower, and can produce 13 megawatts of electricity. They are adjusted for wind variances, sufficient to power thousands of households continuously.
Engineers are in the early stages of developing airborne wind turbines. The components are either buoyed by a gas such as helium or utilize their aerodynamics to remain high in the air, where the wind is greater. These devices are being evaluated for usage offshore, where traditional wind turbines on tall towers are prohibitively expensive and difficult to build.
Trees, which can survive gale strength and yet move in response to gusts from any direction, also inspire new wind energy technology concepts. Engineers have speculated on the possibility of creating artificial wind-harvesting trees. This would necessitate the development of novel materials and systems capable of converting the energy contained in a tree's complicated movements into the continuous rotation required by conventional generators. Wind energy harvesting closer to the ground with smaller, less visible devices and in areas with complex airflows, such as cities, is the prize.