Fuel cell plane for zero emission flying
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The HY4 powertrain has already been tested successfully in the lab. To create enough lift to take off, the system must provide the maximum takeoff performance reliably for at least three minutes. During the test, the developers already succeeded in running the system for more than ten minutes at maximum power. The interplay between fuel cell and the battery, which unites the functions of an energy buffer and back-up power system, has also been proved. This paves the way to integrate the powertrain into the plane.
http://www.electronics-eetimes.com/news/fuel-cell-plane-brings-zero-emission-flying-within-reach-0
Boeing flight-tested the first manned fuel cell aircraft back in 2009.
My next thought is of methanol... A popular fuel for fuel cell forklifts. More dense and decidedly renewable.