June 21, 2005

The myths of wind power ...

An article in the June 10 Daily Hampshire Gazette (Northampton, Mass.) describes the controversy of industrial wind facilities, using a tour of the Searsburg, Vt., turbines led by Enxco representative Martha Staskus as the framework. Here are a couple of comments about some things Staskus said.
One of the myths about wind power, says Staskus, is that it's unreliable. On the contrary, she says, the turbines at Searsburg are on line over 90 percent of the time and need little maintenance or oversight. "It's a very efficient operation," she says.
Being "on line," or available, is a lot different than generating power. (And even during this tour, 2 of the 11 turbines were down for repairs, and 1 was turned off for the safety of the visitors.) Searsburg's turbines average about 89% availability but they generate electricity -- even the slightest trickle -- just over 60% of the time, according to a report by the Electric Power Research Institute.

In addition, Searsburg's output has decreased every year since beginning operation. It was down to 20.4% of its capacity in 2003, producing less than 11,000 MW-h, an average generation rate of 1.25 MW. The average residential customer of Green Mountain Power uses 7.5 MW-h annually (an average load of 0.85 KW), so Searsburg's output is equivalent to the use of less than 1,500 "homes." But two-thirds of the time, because the generation rate falls off sharply below the ideal wind speed, output is much less, and almost 40% -- two-fifths -- of the time it is zero. That is, they are very rarely providing power for any homes, much less the nonresidential needs of the grid. Further, when the wind picks up, for example, at night, is not necessarily when people need extra electricity.
But Staskus cites the most important benefit of wind: clean power. Searsburg produces enough electricity to light 2,000 homes annually, and in doing so displaces about 60 tons of sulfur dioxide and 12,000 tons of carbon dioxide that would otherwise be emitted by fossil-fuel plants, according to statistics provided by enXco.
In Vermont, the emissions argument is especially weak, because more than two-thirds of our electricity is emissions free (hydro and nuclear -- the latter, however, with its own serious problems) and none is from coal, the main cause of acid rain. According to the U.S. Energy Information Agency, Vermont's annual emissions from electricity production in 2002 were 17,000 tons of CO2, 141,000 tons of NOx, and no SO2 at all. Searsburg's output is equivalent to 0.2% of Vermont's electricity consumption. So, pretending that 1 MW of wind power displaces 1 MW of nonwind power, that means Searsburg "saves" 282 tons of NOx (and no SO2) and 34 tons of CO2. According to the EPA, that's equivalent to the CO2 emissions of 2 cars. The U.S. as a whole emitted over 6 billion tons of CO2 in 2002.

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