Energy from coal costs around $100 per megawatt-hour to produce. The price for solar power and offshore wind generation starts at twice that much and climbs fast. Some committed environmentalists might not mind seeing their electric bills nearly double. Most other folks would—even if they say otherwise.
http://reason.com/archives/2011/09/13/the-renewable-energy-boondoggl

This isn't good news, or anything to crow about - but pretending it is not true, pretending that we can afford to pay twice as much, is dangerous.
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Then there is the Cuisinart conundrum: Wind farms already kill half a million birds a year while generating just 2 percent of U.S. electricity. How many birds would they kill generating the 20 percent that renewable advocates want to shoot for?
Wind's biggest problem, however, is that it is intermittent. Since utility-scale electricity can't be efficiently and effectively stored, utilities must back up wind farms with other generation. And while utilities can fire up another gas turbine or two when demand is high, they cannot make the wind blow. Ironically, demand often peaks during hot summer days when the winds flatline.