From Barton, Vermont, to the German border with Denmark and from the shores of Lake Huron, to the Romney Marches of southern England, wind power advocates are fighting crosswinds from local residents. In Barton in mid-January, a referendum overwhelmingly rejected the wind power turbines that were planned near this upper Vermont community. ...In Germany, where one-third of the world's current wind power is generated, doubters have provoked a loud debate. The company that owns the grid that includes nearly half the wind-farms in Germany reported its wind farms generated only 11 percent of their capacity. The company said the winds vary so much the wind farm had to be backed 80 percent by the conventional power grid.

The potential for growth, most analysts argue, is clear. But bottlenecks and political setbacks, not to mention technological glitches, will create many bumps in the road ahead. Indeed, fears that the most euphoric investors were overlooking such obstacles seem to have contributed to a sharp fall in clean-energy stocks earlier this year-although they have since recovered much of the lost ground. Such jitters caused several green-energy firms to cancel planned flotations. “There’s legitimate debate about a couple of segments,” says Keith Raab, boss of Cleantech Venture Network. In some instances, valuations accorded to firms with no profits-and little chance of making any soon-were reminiscent of the excesses of the dotcom bubble. As Douglas Lloyd, of Venture Business Research, puts it, “There’s too much money chasing too few opportunities. How is it possible that this many solar companies are going to succeed? They’re not.”