The European Wind Energy Conference has adopted the European Commission’s estimate that 12 percent of electric energy could be from wind by 2020.
That wind figure is limited to 12 percent by the fact that wind is an intermittent power source. The variability problem is especially acute in summer during those sultry days when there isn’t a breath of air, and electricity demand is highest. High winds create excess power, which often can’t be stored or used. Variability causes the actual capacity of wind turbines to be less than the so-called nameplate capacity.
Germany, Denmark and Spain have Europe’s most aggressive wind-energy programs. Denmark’s thousands of turbines have a nameplate capacity equal to 20 percent of its total electric power, but the actual wind contribution is about 6 percent. Germany’s 16,000 turbines provided 5.7 percent of its electric power in 2006.
For the United States as a whole, wind systems provide less than 1 percent of our electric power. They operate at 29 percent to 30 percent of nameplate capacity, according to the Renewable Energy Laboratory at the University of Massachusetts.
Undeterred by all this technical stuff, our Legislature passed Renewable Energy Standard Bill SF0004, which requires Xcel Energy to use an optimistic 30 percent renewable (at least 25 percent wind) energy by 2020. With the stroke of his gubernatorial pen, Gov. Tim Pawlenty signed legislative law SF0004, thus inking out those pesky physical laws. (He and the Legislature did rely on an elaborate, though also optimistic, technical study that suggested a 20 percent target for wind energy.)
Wind can be a significant part of our future energy needs, but it’s important to be realistic. In Minnesota, the best windy sites are on our western border. Unfortunately, the state’s population and power plants are in the east, requiring a sizeable, as yet unplanned, transmission grid.
Passing paper laws is easy; the laws of nature are a little tougher to amend.
Rolf Westgard
Deerwood
19 May 2007
URL to article: https://www.wind-watch.org/news/2007/05/19/winds-unpredictability-affects-energy-reality/