What's behind Duke's wind-power push?

Duke Energy, one of the biggest coal-burning utilities in the U.S., just added another clean-energy company to its growing portfolio. The Charlotte, NC-based company will pay $320 million for Catamount Energy Corp., a small wind-power developer based in Vermont.

There are a few possible readings here. First, maybe rising capital costs of coal and nuclear power plants-as well as rising fuel costs for coal and natural gas-really are turning the tables against traditional ways to generate power and toward renewables like wind power. Duke said as much:

"You can build large utility scale wind farms and power plants relatively fast compared to anything else and build them cheaper than any renewable energy at this stage. That makes wind very attractive to us," [Duke Energy Generation Services president Wouter] van Kempen said in a conference call with reporters.

Wind power is certainly growing fast, even if Congress hasn't gotten around to extending clean-energy tax credits. Plenty of states are boosting renewable-energy targets. The Department of Energy is chuffed about wind's potential. And even if the Lieberman-Warner climate bill sank, U.S. industries know there will be some pricetag put on carbon emissions pretty soon. That will make wind (and nuclear) more attractive.

But maybe the deal is just a way to burnish Big Power's image at a time when energy companies are taking fire from all directions. Catamount's wind-power assets are a drop in the bucket compared to Duke's overall generation mix. Catamount's U.S. assets, part of the massive Sweetwater wind-farm complex in Texas, equates to about 300 megawatts of power, or about one-quarter of some of Duke's big coal-fired plants and less than 1% of Duke's total generation portfolio.

The Catamount acquisition comes after other small clean-energy deals, like a plan to buy a tiny bit of solar power in North Carolina. Duke certainly has been winning green kudos lately; witness the big profile in the NYT Sunday magazine that called Duke boss Jim Rogers an "environmentalist."

But, taken together with last year's purchase of Sierra Energy, Duke says it now has a wind-power project pipeline of 5,000 megawatts-or the rough equivalent of five big coal plants. Granted, not all those projects will pan out-wind-industry pipelines are notoriously padded. So where is Catamount developing all those new wind farms? Mostly in the U.K.

Which, coming as it did the same day that British Prime Minister Gordon Brown announced a 100-billion-pound "green revolution" to push renewable energy in the U.K., suggests a third possible reading for Duke's purchase.

After years in which the U.S. became the wind-power holy land and attracted massive investment from Europe, is political dithering over clean-energy policy in the U.S. knocking the ball back into Europe's court?