If you've ever measured your own carbon footprint, you know that frequent flying really takes a toll on the environment. And if you've bought plane tickets recently, you know that fuel costs are a huge part of the price you'll pay. Yesterday, Continental Airlines became the first major American airline to fly a plane powered in part by alternative fuels.

A Continental Boeing 737-800 jet left Houston's Bush International Airport with no passengers, and flew for one hour and 45 minutes. One of the plane's two engines used regular fuel, and the other used a mixture of half regular fuel and half biofuel derived from algae and jatropha plants. According to Continental, the biofuel exceeded specifications for regular jet fuel, and no modifications to the plane or its engines were needed, but it will still be many years before airlines are able to really use alternative fuels on a large scale. There simply isn't enough available right now.

Biofuel sources like algae and jatropha are sustainable, but there aren't enough facilities producing the biofuel to supply airlines with the volumes they need. 2008's fuel spike has given the biofuel industry a boost, though, and some experts predict that airlines will be using as much as 20% biofuels in planes within the next decade. As biofuel production increases and becomes more efficient, it will be able to compete more with petroleum. With sustainable sources, we shouldn't see such drastic price swings in biofuels as we've seen in the past few years in regular jet fuel and gasoline. When airlines begin to regularly integrate alternative fuels, we can expect to see cheaper, cleaner flights. Sounds like a win-win.