1. WIND POWER

2. WHAT IS WIND?!  Caused by uneven heating of the Earth’s surface  Made of very different types of land and water, absorbs sun’s heat at different rates  Air above the land heats up more quickly than the air over water  Warm air over the land expands and rises Heavier, cooler air rushes in to take its place

4. WHAT IS WIND?!  Atmospheric winds that circle the earth are created because the land near the Earth’s equator is heated more by the sun than the land near the North and South poles  The winds are reversed at night because the air cools more rapidly over land than water

5. WIND TURBINES  Use blades to collect the wind’s kinetic energy  Wind flows over the blades creating lift, which causes them to turn  Blades are connected to a drive shaft  Turns an electric generator to produce electricity  2 different types used today

6. WIND TURBINES  Sizes of the turbines vary  Small ones have a capacity of less than 100 kilowatts  Used to power a single home or business  Large, commercial-sized ones may have a capacity of 5 million watts (5 megawatts)  Often grouped together into wind farms that provide power to the electrical grid

7. HORIZONTAL-AXIS TURBINES  Look like windmills  Most common type  Stands as tall as a 20- story building, has 3 blades that span 200 feet across  Stand tall and wide to capture more wind

8. VERTICAL-AXIS TURBINES  Look like egg beaters  Blades go from top to bottom  Darrieus wind turbine is the most common type  Named after French engineer Georges Darrieus Patented it in 1931  Typically stands 100 feet tall and 50 feet wide  Make up only very small share of wind machines today

9. WIND PRODUCTION  Wind machines in 2008, generated a total of 52 billion kilowatthours  About 1.3% of total U.S. electricity Enough electricity to serve 4.6 million households or to power the entire state of Colorado  Between 2006 and 2008, wind generation has nearly doubled

10. A CLEAN FUEL  Wind power plants (wind farms) produce no air or water pollution  No fuel is burned to generate electricity  In 1990, California’s wind power plants offset the emission of more than 2.5 billion pounds of carbon dioxide (U.S. Department of Energy)  Wind energy is free & renewable

11. cost  Higher initial investment  Roughly 80% of cost is machinery  Compared on a “life-cycle” cost basis, wind costs are more competitive because there is no fuel to purchase & minimal operating expenses