1. Period 11 the tension group, md ds ay bp as

2. How it works  Wind is a form of solar energy. 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. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.

3. Where it’s being used now  In the United States, wind power is most commonly used in the West, home to some of the windiest areas in the nation, but wind power is expanding in all parts of the country.  California most, Texas 2 nd

4. Cost/Availability  The cost of wind energy has come down 85 percent in the last 20 years, according to the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy. In 2002, wind power cost 4 to 6 cents per kilowatt- hour, a price that is competitive with new coal- or gas-fired power plants.

5. Environmental Concerns  Although wind power plants have relatively little impact on the environment compared to fossil fuel power plants, concerns have been raised over the noise produced by the rotor blades, visual impacts, and deaths of birds and bats that fly into the rotors (avian/bat mortality)

6. Why we don’t use it more  The production of wind power varies and is harder to forecast than the fluctuations in electricity demand. Adding large quantities of wind power to power systems is therefore challenging.

7. Works Cited  http://www1.eere.energy.gov/windandhydro/ wind_how.html http://www1.eere.energy.gov/windandhydro/ wind_how.html  http://www.nrdc.org/air/energy/renewables/ wind.asp http://www.nrdc.org/air/energy/renewables/ wind.asp  http://www.sciencedaily.com/releases/2007/1 2/071207000819.htm