A few years back, my local utilities company invested in an expensive wind power project in New Mexico.

Anyone who supports renewable or alternative energy has the option to sign up for wind power (or at least a portion of it) and pay a few extra dollars per month to help offset the cost of the project.

I signed up, and I've been proud to display a "Wind Power" bumper sticker on my car to let the world know that I think it's a worthwhile cause. (Yes, I see the irony of slapping these stickers on a fossil-fuel-using car, but that's the way it is.)

Anyway, I was -- and still am -- glad to do something that lessens our reliance on fossil fuels, and have no problem spending a few bucks to make alternative power more of a reality.

So I was dismayed when I read this article on LiveScience.com about a new study that's found that renewable energy may not be as green as we might like to believe.

According to the study, many of our most common renewable energy alternatives -- including wind farms, biomass, damming rivers, solar power -- would disrupt nature and existing ecosystems in profound and destructive ways.

The study found that:

• Producing enough electricity to meet the U.S. demand would require a wind farm the size of Texas.

• Powering New York via wind energy would require wind farm the size of Connecticut.

• Solar power and biomass are "un-green" because the amount of land required would to make any gains would ultimately do more harm to the environment.

Fortunately, these findings were disputed by other scientists and environmentalists who don't buy into the study's "energy density" scenario. They argue that calculating energy density may not be the most reliable way to assess whether renewable resources are effective.

More importantly, while reading the article, I couldn't help but notice that the study seemed to have a slant towards using nuclear power. In fact, the lead researcher stated that nuclear power is more environmentally responsible than renewable resources.

Personally, I see the reasons to support -- as well as to resist -- nuclear power. But I'm not ready to give up on renewable power alternatives yet.

And, until I'm convinced otherwise, my "Wind Power" sticker is staying on my car.