We have all seen those creaky old mills on farms and although they may seem about as low tech as you can get, those old wind mills are the predecessors for new modern wind turbines that generate electricity. The same wind that is used to pump water for cattle is now turning giant turbines to power cities and homes. Today’s wind turbines are much more complicated machines than the old prairie wind mills but the principle is the same: both capture the wind’s energy.
How does wind energy work?
A wind turbine’s blade works like an airplane, blowing air passes along both sides of the blade. The shape of the blade causes the air pressure to be uneven, higher on one side of the blade and lower on the other. And that is what makes it spin: the uneven pressure causes the air to spin around the center of the turbine. On the top, there is a weather vane that is connected to a computer to keep the turbine turned into the wind so that it captures the most energy. The blades are attached to a shaft, which turns about 18 revolutions per minute (rpm), which is not nearly fast enough to generate electricity by itself. So the rotter shaft spins a series of gears, which increase the rotation up to 1800 revolutions per minute, and at that speed the generator can produce a lot of electricity.
So why are wind turbines so tall? Because the higher up you go, the windier it is. More wind, naturally means more electricity, and in many cases larger turbines can capture energy more efficiently: the blades can sweep a circle in the sky as long as a football field (up to 130 ft). What is really cool is that even a small wind farm can generate enough electricity to power more than 9,000 homes, and larger farms can provide much more clean wind energy for our homes and businesses.
Benefits of wind turbines
There are a number of specific benefits that can be derived from wind turbines:
1. Unlike other costly energy resources the wind is free, and its power can be harnessed efficiently.
2. Wind energy does not cause any pollution to the air we breath.
3. Wind turbines require only a small plot of land to be built on. This makes them attractive to agricultural areas both in the US and in the developing countries where this land can be used for farming.
4. Remote areas both in the US and abroad, particularly in developing countries, which are not yet connected to the grid can use wind turbines to produce their own supply of electricity.
5. Wind turbines can come in a variety of sizes which means that they can be used by a wide range of consumers from home owners, to businesses, to small villages, depending on individual needs.
6. Wind energy provides more jobs per unit of energy produced than any other form of energy. The number of people employed by the industry worldwide is estimated to be 100,000. Each megawatt of wind provides 2-1/ to 3 job years of employment.
7. Wind turbines provide financial benefits to farmers and other landowners who lease the land wind farms are built on. The lease payments help bolster their incomes and the farmers are still able to use their land for farming.
8. By using wind energy to power our homes and businesses, we can strengthen our energy independence and lessen our reliance on fossil fuels. For every kilowatt hour generated by wind turbines, one less kilowatt hour is needed from polluting fossil-fueled power plants.
9. Wind energy is reliable and efficient. Unlike other power plants, wind energy systems require minimal maintenance and have low operating expenses.
10. Wind energy is cost competitive to other fuel sources, like natural gas. Notably, it is the least expensive of all renewable energy sources. Wind energy provides a stable long-term price for power production. Today’s wind farms can generate electricity for less than 5 cents per kilowatt hour in many parts of the U.S., a price that is competitive with new coal- or gas-fired power plants. The cost is expected to continue to decline as the technology improves and the market for this source develops.
Wind energy around the world
Countries around the globe have been steadily increasing the use of wind energy, and it has been the world’s fastest growing renewable energy source for more than a decade, with an average annual growth rate of over 20%. In 2008, worldwide wind energy capacity passed the 120,000 MW mark, representing a 28% increase over 2007. That same year, the United States had a record breaking year by increasing generating capacity by 50%. As a result, the United States has overtaken Germany as the world’s leader with 25,170 MW of total installed capacity. This amount is enough to power more than 7 million average U.S.households According to the American Wind Energy Association, wind energy in the United States could provide as much as 10,777 billion kWh annually—more than twice the electricity generated in the U.S.today. Germany is second with 23,903 MW. Spain, which generates 10% of its electricity from the wind, is third with 16,754 MW of installed capacity. China is fourth with 12,210 MW and India is fifth with 9,645 MW. France, the United Kingdom and Portugal continue to be growing markets for wind energy as well.