May 2005

Wind Power Upgrade

Turbine technology looms large.

By David Talbot

Wind power, already the world's fastest-growing source of electricity, is picking up still more momentum. The wind industry in Europe -- the epicenter of wind power adoption -- expects that one-quarter of the continent's new electricity-generating capacity in the next decade will come from wind. To both spur and serve this demand, manufacturers are developing colossal new offshore wind turbines with blade spans that exceed the length of a football field -- including the end zones.

Today's largest commercial wind turbine has a blade span of 104 meters and produces up to 3.6 megawatts of electricity -- enough to power 1,000 average U.S. households. But in February, Repower Systems of Germany switched on a demonstration turbine near Hamburg that produces five megawatts and has a blade span of 126 meters. And General Electric is developing a design for a 70-meter blade, which translates to a total blade span topping 140 meters. GE doesn't yet have a timeline for building such a massive machine but believes a turbine of that size could produce as much as seven megawatts, says Jim Lyons, chief tech­nologist at GE Wind.

"The economics work better as the turbines get bigger -- and the name of the game is economics," says Bob Thresher, director of the National Wind Technology Center, a fed­eral lab in Boulder, CO. The goal of industry and federal researchers is to create wind farms that produce electricity for about three cents per kilowatt-hour, down from about 4.5 cents today; that would beat the cost of fuel for the most efficient new gas-fired power plants -- currently about 3.5 cents per kilowatt-hour. If the development process goes well, Thresher says, these huge turbines should be ready for widespread wind farm use in 2012.

Still, relying on superbig machines is not without risk, notes John McGowan, a mechanical engineer and wind energy expert at the University of Massachusetts Amherst. The bigger the turbines get, the higher the cost if one of them fails. "Sooner or later, they are going to make one too big," says McGowan, "and they are going to lose their shirt." And, he adds, efforts to develop turbines in the five- to seven-megawatt range are still too immature to yield reliable estimates of the cost of deploying them in wind farms.

Global wind power capacity grew 20 percent last year, and power-grid operators are wrestling with ways to integrate that increased output into today's transmission system. Bigger turbines churning out still more power would make solving that problem all the more critical. Wind farms' productivity fluctuates with the weather, and that's a challenge on the electrical grid, which must maintain a constant balance of supply and demand. Hydroelectric power, where available, can provide some stability. For example, last year Canadian Hydro Developers built a wind farm next to a hydroelectric plant in southern Alberta. Grid managers are also turning to advanced wind forecasts to help them plan ahead, tapping supplementary capacity or purchasing additional power as necessary.

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