You read that right. Vehicle hybridization has turned its CO2-reducing attentions to the air-travel industry. The next-generation Boeing 737 aircraft is being adapted for use as an external-combustion/electric hybrid, with the small on-board auxiliary-power unit turbine generating enough electricity to propel the aircraft under certain circumstances at speeds of up to 20 mph. Okay, taxiing under electric power may not seem glamorous, but trust me, you'll love it.

Imagine being able to leave the gate as soon as the last overstuffed suitcase has been jammed into an overhead bin without waiting for an airport tug and driver to push the plane out to the active taxiway. Green-minded travelers will love the fact that letting electric motors tow them all the way out to the runway saves tons of CO2 and precious jet fuel. One estimate suggests that leaving a new 737's wing engines off while taxiing and idling before takeoff could save 200 pounds of fuel per flight, eliminating 500-1000 tons of CO2 per plane per year depending on its flight schedule. Other cost savings include reduced brake wear, no damage from clumsy airport-tug operators, and reduced turn-around time because ground personnel won't have to wait for engines to cool. All together, total monthly savings could reach $60,000, according to Isaiah Cox, CEO of WheelTug, the subsidiary of Chorus Motors plc., which is developing the concept. Surely some of that savings will trickle down to lower ticket prices.

So how does an electric wheel motor small enough to go up and down on a plane's landing gear manage to pack enough punch to accelerate a 300,000-pound aircraft to 20 mph? With black magic and witchcraft (well, their words are "mesh-connected windings" and "fundamental harmonics"-visit chorusmotors.com). These esoteric concepts combine to deliver the efficient low-speed torque of a permanent magnet motor (such as the ones in most hybrid cars) with the light weight, lower cost, and better high-speed performance of an AC induction motor (as in the Tesla and Chevy Volt).

... read more here: http://www.motortrend.com/features/editorial/112_0901_flying_hybrids_technologue/index.html