We've covered the ongoing development of solar-powered airplanes, which look almost space-age as they fly silently through the sky. But if sustainable aviation fuel is going to come from anywhere in the near future, it won't be from solar but from biofuel. Continental ran a biofuel-powered test flight last January out of Houston and flew around the Gulf of Mexico, and now Alaska Airlines is investigating whether biofuels can be used more broadly. The airline is teaming up with Boeing and Washington State University to run a pilot biofuel program across three Northwest airports.

PDX, SeaTac, and Spokane will see whether they can become part of their own little biofuel sub-industry, where nearby algae, agriculture, and wood byproducts are converted into something that can keep airplanes in the air. The details are a little sketchy but the idea—local, non-fossil fuel materials—seems pretty straightforward.