Altamont Pass, Calif. The PG&E system in California operates normally when wind generation supplies up to 8 percent of its system demand.
Photo by Warren Gretz courtesy of National Wind Technology Center at NREL (National Renewable Energy Laboratory).
If solar power can make hydrogen, it can surely make wind. (Quickie explanation: The sun heats the atmosphere, either directly or by warming the earth. When this air warms it expands and becomes less dense. When the warming air is shouldered aside by colder, denser air, the resulting movement is called wind.)
Although wind has been generating electricity since the 1930s, the revival of interest in wind power dates to the oil crises of the 1970s. Today, what was once a small-scale solution for those who wanted to be independent of the electric grid is becoming a fast-growing source of energy. But the big action is no longer in individual windmills supplying homes. Today, it's in giant wind farms supplying the utility grid.
For the past three years, worldwide wind-electricity capacity has grown 25 percent per year. According to the American Wind Energy Association, 1520 megawatts (MW) of new installations came on line in 1997, mostly in northern Europe.
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A megawatt -- one million watts of electric power -- is used to describe the capacity of electric generators. If wind generators worked at full output all the time, one megawatt of capacity would serve the average needs of about 380 people in the United States, together with their share of industry and agriculture. But wind turbines actually produce about 23 percent of their rated capacity when averaged over the year, says Michelle Montague, communications director of the American Wind Energy Association. Turbines can't operate in light winds, and they shut down in heavy winds to avoid damage (a limitation that will fade in time, as you'll read below). |
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Growing fast
The German and Danish governments, for example require utilities to pay 12 to 15 cents per kilowatt-hour for wind. This and other incentives have pushed Germany past the United States to become the world's largest wind energy producer. In Denmark, which already gets 7 percent of its electricity from wind, wind-energy products are the second largest export; the industry employs 8,600 people.
In the United States, incentives are lower but still significant: a federal tax credit pays electricity generators 1.7 cents for every kilowatt hour of wind energy produced. The credit, applicable only to machines that generate electricity before June 30, 1999, helps explain why almost 800 MW of new wind power is scheduled to come on line by the end of 1999. (Here's the home of one big player.)
The dramatic growth in Europe reflects a large demand for new electricity and improvements in technology. It also reflects politics, specifically the 1996 Kyoto agreement on climate change, which committed governments to stem global warming, and political support for alternative energy. Susan Hock, manager of the wind energy program at the U.S. National Renewable Energy Laboratory, says public environmental consciousness has induced many European governments to support renewable energy in concrete (read financial) ways.
You can't see it, but it's there
Believe us, wind is nowhere near that level yet. The United States has about 2,000 MW of wind capacity, accounting for a measly 0.3 percent of total generating capacity. (Don't believe us? Check these stats on conventional and alternative power.)
Despite what Montague says is an 80 percent drop in the cost of generating wind electricity over the past 25 years, wind remains more expensive than fossil fuels -- if environmental costs are ignored.
According to Hock of the renewable lab, the cost of wind delivered to a substation ranges from 4 to 5 cents per kilowatt hour, while coal comes in at about 2 to 3 cents. "If you do it on a pure cost basis, compared to coal, wind is more expensive," she says.
Why should anything interfere with the logic of the market and ask consumers to pay more than absolutely necessary for electricity? To reduce global warming, and other energy-associated pollution, such as acid rain and oil spills, says Hock. Governments have recognized the "non-cost" values of wind, she says, and "are giving value to this."
Some consumers apparently think likewise, judging by the success of "green electricity" programs in the United States, which charge a premium of a few cents per kilowatt-hour.
Making sense of wind.
The near-gale of interest in wind reflects the simple fact that there's so much of it. Turbines installed on less than 1 percent of the 48 contiguous states could provide 20 percent of current U.S. power needs, according to an estimate by Christopher Flavin of the Worldwatch Institute. He says wind could eventually rival hydropower -- which now produces about 20 percent of the world electricity supply.
