Friday, May 31, 2019

Hydrogen planes, not battery?

There's a start up planning on making a small, boxy commuter "flying car" powered by hydrogen fuel cells.   The mock up doesn't look all that inspiring (looks like a slightly bigger version of a passenger drone):


but what's said in the article about the energy density of fuel cells is interesting:
The argument for fuel cells boils down to energy density: One pound of compressed hydrogen contains over 200 times more energy than one pound of battery, says Alaka’i founder Brian Morrison. That means the Skai can meet the speed, range, and payload requirements that Alaka’i thinks will make it competitive, while saving a lot of weight—a top line consideration for anything that flies. Though the company won’t reveal specifics surrounding the power system, it suggests that it and its fuel cell provider (also not disclosed) have made “breakthroughs” with the technology that enable this performance.

Hydrogen fuel cells are proving themselves able to significantly boost run times for vehicle systems, with certain small unmanned aircraft jumping from 30- to 45-minute run times with batteries to more than two to four hours with fuel cells, says Thomas Valdez, a chemical engineer with Teledyne Energy Systems. And they offer a safety benefit by eliminating the risk of thermal runaway. Even a punctured tank is no big deal: “Pressurized hydrogen would very quickly dissipate in the air, so it won’t pool or catch fire the way conventional fuels do,” Valdez says.
I would still think a pressured hydrogen tank would be the safest thing in a crash.   But nor is normal aviation fuel, of course.

Anyway, one way or another, it seems our future cities will look a bit Blade Runner-ish.

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