How Things Work: Wind turbines
Wind power is not a new invention. Windmills have been around for centuries, grinding grain and pumping water. However, for just over a century, the energy of wind has been transformed into usable electrical energy. It has become one of the most widely discussed energy topics in the scientific field today. As a viable source of energy in the future, learning the details behind wind turbine technology is important. How do wind turbines work, and how have they impacted the availability of usable energy?
Industrialization played a huge role in the development of wind turbines. According to the U.S. Department of Energy website, wind turbines appeared in Denmark as early as the 1890s. However, interest in wind power did not significantly increase until the 1970s, when oil embargos raised the price of fossil fuels greatly and people sought a less expensive form of energy. Wind power has become so widely used that the Battelle Pacific Northwest Laboratory, part of the Department of Energy, predicts that 20 percent of American energy could eventually be provided by wind power.
Modern forms of federal legislation have also encouraged the growth of directed wind power. According to www.realclearpolitics.com, through President Barack Obama’s stimulus plan, $2 billion was directed toward the wind power sector, which made companies involved with wind turbine production eligible for tax credits. An energy bill, drafted by Congress in the wake of the BP oil spill in the Gulf of Mexico, aims to reduce greenhouse gases and place more emphasis on green technology.
The basic structure of a wind turbine, according to www.HowStuffWorks.com, resembles that of any household fan. However, instead of using mechanical and electrical energy to create wind energy, a wind turbine uses wind energy to create mechanical and electrical energy. Typically two to three blades are attached to a rotor, and when the wind hits the blades, the fans spin a cylindrical, low-speed shaft inside the rotor. Blades start spinning when wind speeds reach eight to 16 miles per hour. On the other end of the shaft is a gear box, which increases the rotational speed to about 1,000 to 1,800 revolutions per minute on another shaft. This high-speed shaft drives the generator, located at the back end of the rotor. The rotations of the shaft in the presence of several electromagnets surrounding a coiled wire induce a voltage. The voltage then transfers an electrical current out of the turbine and into power lines.
Some wind turbine structures follow the vertical-axis wind turbine, or VAWT, structure, in which the shaft is mounted on a vertical axis so that the now-vertical rotors are aligned with the wind. Unfortunately, the VAWT structure requires an initial jolt of energy to begin rotation, and the close proximity to the ground reduces the amount of wind available for it to use.
Almost all of the turbines currently in use are the horizontal-axis wind turbine, or HAWT, which allows the blades of the turbine to clear the ground and maximizes the amount of wind that it may use.
It’s easy to see the allure of these turbines. They generate, for the most part, almost no pollution or atmospheric emissions, unlike fossil fuels that require a combustion reaction in order to extract their energy. Wind is an unlimited resource, so there’s no danger of running out of available power for the turbines to harness. The economic benefits are also attractive to researchers, since each kilowatt-hour of energy only costs between four and six cents, and the turbines can be constructed in rural areas to boost their economies.
Wind energy is not without its drawbacks, however. The turbines often require an isolated location, so more transmission lines must be built in order to send the electricity to cities and towns. The technology, furthermore, requires a greater startup investment than fossil fuel generators do.
Although the economic viability of wind turbines is up for debate, wind turbines have become one of the prominent ways to tap into a natural form of energy and use it to power 21st-century technologies.