Why choose wind power

Wind-power Resources and Economics

On a global scale, wind turbines are currently generating about as much electricity as eight large nuclear power plants. That includes not only utility-scale turbines, but also small turbines generating electricity for individual homes or businesses (sometimes used in conjunction with photovoltaic solar energy). A small, 10-kW-capacity turbine can generate up to 16,000 kWh per year, and a typical U.S. household consumes about 10,000 kWh in a year.

A Watt? · Watt (W) - electricity-generating capacity 1 megawatt (MW, 1 million watts) of wind power can produce from 2.4 million to 3 million kilowatt-hours of electricity in one year. · Kilowatt-hour (kWh) - one kilowatt (kW, 1,000 watts) of electricity generated or consumed in one hour See How Electricity Works to learn more.

A typical large wind turbine can generate up to 1.8 MW of electricity or 5.2 million KWh annually, under ideal conditions -- enough to power nearly 600 households. Still, nuclear and coal power plants can produce electricity cheaper than wind turbines can. So why use wind energy? The two biggest reasons for using wind to generate electricity are the most obvious ones: Wind power is clean, and it's renewable. It doesn't release harmful gases like CO 2 and nitrogen oxides into the atmosphere the way coal does (see How Global Warming Works), and we are in no danger of running out of wind anytime soon. There is also the independence associated with wind energy, as any country can generate it at home with no foreign support. And a wind turbine can bring electricity to remote areas not served by the central power grid.

But there are downsides, too. Wind turbines can't always run at 100 percent power like many other types of power plants, since wind speeds fluctuate. Wind turbines can be noisy if you live close to a wind plant, they can be hazardous to birds and bats, and in hard-packed desert areas there is a risk of land erosion if you dig up the ground to install turbines. Also, since wind is a relatively unreliable source of energy, operators of wind-power plants have to back up the system with a small amount of reliable, non-renewable energy for times when wind speeds die down. Some argue that the use of unclean energy to support the production of clean energy cancels out the benefits, but the wind industry claims that the amount of unclean energy that's necessary to maintain a steady supply of electricity in a wind system is far too small to defeat the benefits of generating wind power.

 

Wind Power Usage in the U.S.

Potential disadvantages aside, the United States has a good number of wind turbines installed, totaling more than 9,000 MW of generating capacity in 2006. That capacity generates in the area of 25 billion kWh of electricity, which sounds like a lot but is actually less than 1 percent of the power generated in the country each year. As of 2005, U.S. electricity generation breaks down like this:

• Coal : 52%
• Nuclear : 20%
• Natural gas : 16%
• Hydropower : 7%
• Other (including wind, biomass, geothermal and solar): 5%

Source: American Wind Energy Association

The current total electricity generation in the United States is in the area of 3.6 trillion kWh every year. Wind has the potential to generate far more than 1 percent of that electricity. According to American Wind Energy Association, the estimated U.S. wind-energy potential is about 10.8 trillion kWh per year -- about equal to the amount of energy in 20 billion barrels of oil (the current global yearly oil supply). To make wind energy feasible in a given area, it requires minimum wind speeds of 9 mph (3 meters per second) for small turbines and 13 mph (6 meters per second) for large turbines. Those wind speeds are common in the United States, although most of it is unharnessed.

When it comes to wind turbines, placement is everything. Knowing how much wind an area has, what the speeds are and how long those speeds last are the crucial deciding factors in building an efficient wind farm. The kinetic energy in wind increases exponentially in proportion to its speed, so a small increase in wind speed is in fact a large increase in power potential. The general rule of thumb is that with a doubling a wind speed comes an eight-fold increase in power potential. So theoretically, a turbine in an area with average wind speeds of 26 mph will actually generate eight times more electricity than one set up where wind speeds average 13 mph. It's "theoretically" because in real-world condition, there is a limit to how much energy a turbine can extract from the wind. It's called the Betz limit, and it's about 59 percent. But a small increase in wind speed still leads to a significant increase in power output.