1. Renewable
1.1. Clean
1.2. Nonpolluting
2. Devices
2.1. Wind-Powered Sailing Ships
2.1.1. Egypt
2.1.2. 2800 B.C.
2.2. Windmills
2.2.1. Persia(Iran)
2.2.2. A.D. 600
2.2.3. convert a portion of kinetic energy into rotational energy
2.2.3.1. turns a shaft
2.2.3.1.1. operates machinery
2.3. wind turbines
2.3.1. modern
2.3.2. drive electric power generators
2.3.2.1. generate electric power
2.3.2.1.1. Denmark
2.3.2.1.2. U.S.
2.3.3. 25,000 by the 1990's
2.3.3.1. 0.1% world's power
2.4. wind farms
2.4.1. 2005
2.4.2. U.S.
2.4.2.1. < 1% power/yr.
3. Kinetic
3.1. movement
3.2. 11 Quadrillion kw-hrs./yr.
3.2.1. kw-hr.
3.2.1.1. work by 1k watts/hr.
3.2.2. 10% of wind energy/yr. > earth's needs/yr.
4. Challenges
4.1. Kinetic Energy
4.1.1. only 59% transferred to blades
4.1.2. only 40% converted to useful rotational energy
4.2. Factors
4.2.1. practical
4.2.1.1. size
4.2.1.2. land
4.2.2. environmental
4.2.2.1. kills birds
4.2.2.2. noisy
4.2.3. speed of wind
4.2.3.1. varies over the earth
4.2.3.2. at times, dies down completely
4.2.3.3. counteract
4.2.3.3.1. storage systems
4.2.3.3.2. back-up generators