NEW YORK (FORTUNE) - All right-thinking people agree that reducing dependence on fossil fuels is a Good Thing. Shifting energy consumption toward renewables such as biomass, wind and solar helps make the world cleaner; and it would be awfully nice not to have to rely quite so much on a certain rather volatile region of the world.

You'd have to be a scum-sucking tool of the filth (ie, oil and coal interests) to disagree.

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But developments in the windpower business illustrate just why the renewables future is taking so long to arrive. Windpower has been the fastest-growing renewable, growing 30 percent a year worldwide from 1990-2003. The cost of wind has fallen sharply, some 90 percent over the last 20 years, making it among the most economical alternatives. And with Europe committed to cutting greenhouse gas emissions to comply with the Kyoto protocol, windpower companies should be printing profits.

Tell that to Vestas (Research), the world's largest wind producer, with 28 percent of the global market. A few weeks ago Vestas, which is based in Denmark, announced its financial results. They were appalling, including an operating loss of 116 million euros - even the company agreed its 2005 performance was "entirely unsatisfactory."

Worse, it was the second year in a row it had lost money - despite revenues that grew strongly, up 52 percent, to 3.6 billion euros. Vestas blamed supply bottlenecks, warranty problems and issues in the American market, where uncertainty over the Production Tax Credit (a subsidy for producers to make wind more competitive) has contributed to a boom-and-bust cycle for producers.

Wind is not yet in a position that it can live without such a subsidy - and that makes it vulnerable. In 2001, for example, when a new Danish government announced its intention to reduce and then eliminate wind subsidies by 2010, Vestas took a blow that it has yet to recover from. Since April 2001, Vestas's stock price has posted a total return of negative 52 percent, while the Copenhagen index has risen 45 percent.

Over in Britain, The Independent - a newspaper entirely run by right-thinking people - reported that a conference in early April on wind energy in London was distinctly downbeat. "Offshore wind," the paper concluded, "is floundering" and larger projects needed more government support. Wind and other renewables will only take off when they can compete in the marketplace without subsidy. That day has not yet come.

And public support cannot necessarily be counted on either. A project to build 130 wind turbines in Nantucket Sound to generate electricity for Cape Cod and the islands looks likely to be scuttled. An unusual amendment to the Coast Guard authorization bill in early April would grant Massachusetts governor Mitt Romney (or his successor) the right to block the project, which would have been America's first off-shore wind farm. Because the project is in federal waters, Romney, who is opposed to the project, would not normally have such veto power. (Congress will vote on the bill April 24.)

What makes this interesting is that the area the wind farm would have served is full of the kind of people who are normally all for renewables. Famously, the Kennedy compound is about 7 miles from the proposed project - in visual range, that is - and both U.S. Senator Ted Kennedy, and his nephew, environmental activist Robert Kennedy, have been ardent opponents.

This is not necessarily hypocrisy (although it might be). The argument over the Cape Wind project is one on which reasonable people can disagree. But it does serve to illustrate that wind cannot live off a sense of virtue alone.

The fact is, wind does have a promising future. The best installations can generate power almost as cheaply as coal, the nation's largest source of power. In the United States, windpower consumption doubled from 1989 to 1999 and then doubled again between 2000 and 2004. It now accounts for enough energy to keep 1.6 million households comfy.

But this is still barely a spark in the turbine that is the U.S. power supply. Wind consumption in 2004 reached .143 quadrillion BTUs; coal and natural gas, respectively, were at 23,000. The U.S. goal is to increase windpower to 6 percent of consumption by 2020 - a goal that is modest enough to be plausible. The term "drop in the bucket" comes to mind.

Ditto for Europe. Despite the continent's generally deeper hue of green, renewables now account for only 12.8 percent of electricity production, barely above the 12.2 percent in 1990. And wind accounts for only 3.7 percent of total renewable consumption, well behind biomass (66 percent) and hydropower (24 percent).

So for all the talk about renewables, it's tempting to conclude that, for both economic and political reasons, we're talking about a little substance and more than a little hot air. In other words, Kermit got it exactly right: It's not easy being green.