Algae in the Tank

It's a bit expensive right now, but it certainly holds promise.

Algae Emerges as a Potential Fuel Source

ST. PAUL, Dec. 1 (AP) — The 16 big flasks of bubbling bright green liquids in Roger Ruan’s laboratory at the University of Minnesota are part of a new boom in renewable energy research.

Driven by renewed investment as oil prices push $100 a barrel, Dr. Ruan and scores of scientists around the world are racing to turn algae into a commercially viable energy source.
Some algae is as much as 50 percent oil that can be converted...(complete article here).