Wind for Power Has Big Hurdle: It Doesn't Blow on Demand

Dec 28, 2006, International Herald Tribune

Wind, almost everybody's best hope for big supplies of clean, affordable electricity, is turning out to have complications.

Engineeers have cut the price of electricity from wind by about 8-percent in the last 20 years, setting up this renewable technology for a major share of the electricity market.

But for all its promise, wind also generates a big problem: because it is unpredictable and often fails to blow when electricity is most needed, wind is not reliable enough to assure supplies for an electric grid that must be prepared to deliver power to everybody who wants it - even when it is in greatest demand.

In Texas, as in many other parts of the United States, power companies are scrambling to build generating stations to meet ever- higher peak demands, generally driven by air conditioning for new homes and businesses.

But power plants that run on coal or gas have "to be built along with every megawatt of wind capacity," said William Bojorquez, director of system planning at the Electric Reliability Council of Texas. The reason is that in Texas, and most of the United States, the hottest days are usually the least windy. As a result, wind turns out to be a good way to save fuel, but not a good way to avoid building plants that burn coal. A wind machine is a bit like a bicycle a commuter keeps in the garage for sunny days. It saves gasoline, but the commuter has to own a car anyway.

Xcel Energy which serves eight states from North Dakota to Texas and says that it is the largest U.S. retailer of wind energy, is eager to have more. Wind is "abundant and popular," said Dick Kelly, the chairman, president and chief executive, speaking at a recent conference on renewable energy.

But Frank Prager, managing directyor of environmental policy at Xcel, said that the higher the reliance on wind, the more an electricity transmission grid would need to keep conventional generators on standby - generally low-efficiency plants that run on natural gas and can be started and stopped quickly.

He said that in one of the states the company serves, Colorado, planners calculate that if wind machines reach 20 percent of total generating capacity, the cost of standby generators would reach $8 per megawatt-hour of wind. That is on top of a generating cost of $50 to $60 per megawatt-hour, after including a federal tax credit of $18 per megawatt-hour.

By contrast, electricity from a new coal plant now costs $33 to $41 per megawatt-hour, according to experts. That price, however, would rise if the carbon dioxide produced in buring coal were taxed, a distinct possibility over the life of a new coal plant. Without major advances in the ways of storing large quanitities of electricity or big changes in the way regional power grids are organized, wind may run up against its practical limits sooner than expected.