Biofuel Takes to the Skies

Electric cars are all well and good; cars sit on the ground, and don't really have to be concerned about the weight of the battery. Electric airplanes? Not so much. Airplanes must worry about weight, and they need a lot of energy. They're limited to engines with high energy-to-weight ratios, and in our current technology, that means internal combustion. So how can airplanes meet society's demand for low carbon?

Biofuels are one way, since they are carbon neutral. Convention biofuels are OK but not great; they generally contain less energy than high-octane gasoline. But one, based on the highly oily plant camelina, produces biofuel that matches jet fuel's even higher energy content. The US Air Force has chosen camelina as its biofuel source of choice. In fact, earlier this year, an F-22 Raptor flew Mach 1.5 using a 50/50 mix of camelina biofuel and conventional fuel, called JP-8. In 2009, a Japan Air Lines Boeing 747 made a short flight with one engine burning a 50/50 mixture of Jet-A and camelina.

And another milestone is on the horizon. Next week, Boeing will make the first Transatlantic flight (video) of a commercial airliner using biofuel, an 85/15 mix of Jet-A and camelina, aboard a new Boeing 747-8 Freighter, on all four engines. It will fly from Boeing's home base inEverett, Washington all the way to the Paris Air Show. The plane will require no modifications whatsoever to use the blend, developed by Honeywell in partnership with Boeing. They've poured enough R&D into this fuel that they expect to get slightly better performance than with Jet-A alone. It will result in an unspecified double-digit reduction in carbon emissions.