I've mentioned before that one of the major ways to frame my 2011 transcontinental ride is as a tour of US energy policy. Among other things I rode across Iowa, then and now a leader in wind power. I saw and photographed a great many windmills, and some of the roads I traveled seemed to carry more turbine parts than any other kind of traffic. At that time they boasted that 4% of the electricity generated in the state came from wind power, and that it was doubling every 24 months. 5 years later and sure enough, 25% of electricity generated in Iowa comes from wind.
Now those numbers aren't really as impressive as they look, because three separate nuclear power stations stand within a half a mile of Iowa's borders in various neighboring states, conveniently located for their power to count against electricity consumed in the state but not against the generation count.
Still, it's pretty interesting to read this morning that the biggest of those three is closing because it no longer makes economic sense to keep it running.