Over the last couple of months, a test pilot has taken Boeing's hydrogen fuel-cell prototype up, up and away ... at low altitudes and low speeds.

Hydrogen fuel cells produce electricity, but unfortunately, electricity isn't very good at powering planes. So far, it's been difficult to produce enough power in such a small, light space.

In fact, the fuel-cell airplane actually needed assistance from a lithium-ion battery pack to take off. Once in the air, however, the power came entirely from the much more energy-dense compressed hydrogen.

It doesn't look like hydrogen is going to solve our problems with consumer air travel. Boeing is hoping that the technology could find a home in unmanned or light-weight aircraft.

Via TreeHugger