One of the two engines of this plane is running on biofuel derived from algae. And it managed to stay in the air.

The only modification required to switch the EADS demonstrator to the eco-friendly fuel was a slight tightening of the engine injection nozzles, due to the algae-juice producing more explosive power than standard JET-A1 fuel. The biggest problem facing the EADS demo plane at the moment is simply finding enough algae fuel—the Farnborough flight nearly didn't happen due to a global lack of algae- breeders and refiners. [The Engineer]