Jim Blair: More than 1,000 turbines needed as sub for Cassville plant

Jim Blair:  —  7/25/2008 5:30 am

Dear Editor:

In the proposed Cassville bio-coal plant discussion in Sunday's Wisconsin State Journal, William Pickett asked how many wind turbines it would take to generate 300 megawatts of electricity.

Here is an estimate. The wind farm in Kewaunee uses 660 kilowatt wind turbines. That would mean 455 turbines if they operated at maximum capacity 24/7. But they don't. Overall they have had an output of 23 percent capacity, which would mean 1,976 turbines to generate 300 megawatts.

The newer Enron wind turbines along Highway 18 west of Madison have over twice that output at 1.5 megawatts. According to the Renew Wisconsin Web page, they have a 19.7 percent efficiency factor. This is probably because the wind is less favorable there, but perhaps also because they shadow each other for other than north or south winds. The Kewaunee turbines are scattered over a larger area and placed far enough apart so as to not interfere with each other. So it would take 1,015 of the bigger turbines to match the proposed Cassville plant.

During calm weather those turbines would not put out nearly as much power as the Cassville plant. Since wind speeds in Wisconsin are typically lowest during the summer, when electric demand is highest, turbines here contribute the least power when they are needed most.

So saying 1,015 large turbines are equivalent to a 300 megawatt plant is rather like claiming that Wisconsin weather is perfect on average: too hot in the summer, but too cold in the winter.

Jim Blair

Madison

Jim Blair:  —  7/25/2008 5:30 am