Since large lithium batteries are a handful -- if not inherently dangerous -- we need to look at alternatives. One is to go back to the heavier nickel-cadmium batteries.
Another is to use fuel cells. Hydrogen fuel cells have proved to be both safe and reliable in warehouse lifts and they now supply unattended electric backup power to cell towers.
Why not use them to make electricity in commercial airplanes? Fuels cells have done precisely that for a decade in our space shuttles.
What about cost? With $16,000 for a lithium battery, cost is relative. Moreover, fuel cells are now a sixth of what they were just five years ago.
What about the Hindenburg? Those flames etched in our minds came from the fresh paint on the tarp. Hydrogen itself burns colorless, last about a second, and the flames go straight up.
But where could we safely store the hydrogen on an airplane? In sturdy tanks of the type now used in fuel cell cars -- and these tanks can be refilled every time the plane refuels.
Or we could store the hydrogen in the new low-pressure metal hydride storage tanks. This might be the way to go since we will gain experience with hydrides and perhaps also learn to use them as pneumatic muscle to operate the plane's wings, brakes and landing gear. A metal hydride driven artificial muscle can be as precise as a step motor, and this by merely varying the current of a heating element inside the hydride tank.