People have been harnessing the power of the wind for thousands of years – since the first sail helped a boat cut through the water. Today, modern wind turbines capture the kinetic energy in wind and convert it to electricity, one of the fastest growing sectors in clean energy. The amount of wind energy in the United States grows by about 30 percent every year, according to the federal government.
The turbines that capture wind energy range from multi-million-dollar commercial machines that can generate up to 10 megawatts of energy to smaller, on-site generators for a single home. A 1-megawatt turbine can make enough electricity to power approximately 350 homes.
The mechanics of a turbine are fairly simple. A tower supports blades that begin to turn when wind speed reaches about 7 mph. Those blades are connected to a drive shaft in a box on top of the tower. As the blades turn, the drive shaft turns and produces electricity. The electricity flows down the tower and into a transformer located outside the turbine. Inside the transformer, electricity from the turbine is converted to a voltage that can flow into the electrical grid.
The amount of energy a turbine can produce depends on the amount of wind in a particular location, but modern equipment generally ranges in size from 660 kilowatts to over 3 megawatts of capacity. Ideal locations have steady winds that blow at least 13 mph.
A 10-kilowatt machine (the size needed to power a large home) might cost around $50,000 to install. Often, federal or state tax incentives can help offset the expense, making wind energy more attractive in rural areas or for use on farms. Commercial towers might be 300 feet tall or more, but residential towers typically stand around 80 feet.
As wind continues to show potential for clean energy, UL engineers have developed safety Standards for both large and small turbines. These standards minimize the risk of fire and shock, assess safety-related systems and address the way the system connects to the utility grid. Other risk factors, like unusual wind patterns, snow, seismic activity and soil conditions, are specific to each turbine location and should be evaluated by local authorities.
Wind power projects in the United States currently have a combined capacity of about 46,900 megawatts, or only about 2.3 percent of the country’s energy supply. But, according to the U.S. Department of Energy, all America’s power needs could be met by the wind resources in Texas and the Dakotas alone.
While interest in wind energy grows, particularly in the Great Plains and Midwest where wind is still a big untapped resource, advances in research have cut wind energy’s costs by more than 80 percent over the past 20 years, fueling rapid expansion in the industry.