I recently heard about some report that says the winds are slowing down in the Midwest of the U.S. Is that true and if so, how will that affect wind power development? – Jake N., Massillon, OH
Jake, you may be referring to a soon-to-be released study on which the Associated Press reported recently. The study indicates that surface wind speeds may have slowed by as much as 10% in some parts of the country and that a possible culprit is global warming.
Suffice it to say, the wind industry knows a lot about wind resource and is constantly working to know more; after all, the businesses that make up the industry depend on the accuracy of that information, and so wind resource assessment is an entire discipline unto itself. With wind resource affecting profit margins, it is common practice within the industry to assess historical wind data over periods of up to 30 years.
What has been the reaction to the study among members of the wind industry and, more specifically, those in the area of resource assessment? Generally speaking, they do not view it as cause for concern.
That’s largely because, as the study’s authors are quick to point out, the conditions under which the wind measurements were taken do not mimic those found at wind farms. Perhaps most importantly, measurements in the study were taken at approximately 30 feet (often using anemometers located at airports), a level that has long been discredited as predictive of the wind resource at the 300-foot height of modern wind turbines. Conversations with leading experts in the wind energy resource assessment field suggest a consensus that there has been no change in wind speeds at hub height.
If there has indeed been a decrease in surface wind speed, the prime culprit may be an unlikely one: reforestation. Notably, the purported decreases in surface wind speeds have occurred chiefly in the regions of the U.S. that have seen the most reforestation. Still, there is no reason to believe that changes in surface wind speeds will have any effect on wind speeds at the height of modern wind turbines; the evidence thus far bears that out.
Finally, even if further studies were to confirm a general downward trend in wind speeds, there inevitably would remain far more good wind sites than needed to supply all of the nation’s energy needs many times over. According to Black & Veatch, there are over 8,000 gigawatts of available land-based wind resources that the industry estimates can be captured economically.
A third-party expert look at the study and the related story is available in a June 11 posting on the RealClimate blog.