"The answer, my friend, is blowin' in the wind." -- Blowin' in the Wind, Bob Dylan (1967).

There seem to be a few truisms regarding alternative energy investing: The companies suck up cash like sponges, their products are not really cost-competitive, and the stocks generate considerable capital losses for those true believers who stick by them.

These are especially true if you limit your gaze to perennial disappointments like Ballard Power (NASDAQ:BLDP), FuelCell Energy (NASDAQ:FCEL), Capstone Turbine (NASDAQ:CPST), and Beacon Power (NASDAQ:BCON). You see much more sizzle than steak (and most of that sizzle is the sound of investors' cash being burned away into the atmosphere).

Look abroad, though, and you see a different picture. In particular, you see Vestas. Vestas Wind Systems is a Denmark-based company specializing in wind power. Unlike its fuel-cell, mini-turbine, and solar-power brethren in the United States, Vestas has actually made money.

With roughly 35% market share around the world, Vestas has managed to build a real business in alternative energy alongside titans like General Electric (NYSE:GE), and Siemens (NYSE:SI). Unfortunately, you can't invest in it easily. Although the company has a Pink Sheets ticker symbol (VWSYF.PK), there's no volume there and investors who want to buy shares have to look to European stock markets to do so.

That's a pity.

Vestas posted more than $3 billion in revenue for 2004, up more than 50% from the year-ago period. Although the company posted a net loss for the year, results were hurt by one-time costs. Still, the company does have positive EBITDA (earnings before interest, taxes, depreciation, and amortization) -- something that many American alternative energy plays can only dream about.

What's the secret behind Vestas? For starters, it hasn't tried to change the world. Instead of crafting technology that forces everyone else to adjust to it, it makes gear that fits into existing systems.

What's more, the technology is cost-competitive. While wind power isn't practical everywhere, in those places where it is appropriate (you have to have wind, after all), it matches up very well. In fact, at about $0.06 per kilowatt-hour, wind power is equivalent in many cases to existing coal or gas-fueled electricity, and that's without any special government handouts or programs.

Vestas might be too difficult for most readers to own, but that doesn't mean that there aren't lessons here for American investors. Optimism about renewable energy is all well and good, but basic economics still wins out in the end. In other words, no matter how cool the technology may be, it's got to make financial sense for the intended end users or it's just a fancy science fair project.

Considering that Vestas booked more revenue in 2004 than American independent fuel cell companies have managed in total, I'd say investors should take heed. A solid business plan and products that are actually economically competitive trump "gee whiz" technology every time.

For more on energy, check out these Foolish opinions:

Will alternative energy stocks ever be true Rule Breakers ? Find out by taking a free, no-obligation trial today.

Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long, nor short the shares).