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Comment by nickff | Hacker News Reader

This is not about financial cost, it is about weight and complexity. It would be less costly and more efficient to separate water into hydrogen and oxygen (using solar power if you like), then use them to power a rocket engine.

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Aircraft weight turns directly into fuel cost via induced-drag. If electric energy is wildly inexpensive, you can afford very heavy airframes.

See https://en.wikipedia.org/wiki/Nuclear-powered_aircraft

There are two major problems with very heavy airframes:

1) Aircraft cost is proportional to empty weight.

2) Range is proportional to total stored energy / drag and drag is proportional to weight. If you have low specific energy, you cannot go far.

One more to add. Current commercial aircraft can jettison fuel to reduce the landing weight and minimize risk if the structure is compromised. Hard to see how this design would.

Jets also constantly lose weight while burning fuel. This results in airliners flying higher and more efficiently as the flight progresses. With batteries, you're kinda stuck with the weight.

And it's true that airliners take off with more weight than they are speced to land with. They have to dump fuel if landing before burning it off.

No reason I can think of why you can't drop empty batteries in an emergency situation. In fact, you probably want swapable batteries to begin with, don't want to waste time on the tarmac charging up.

One reason would be if they're built into the wing surfaces, as this article proposes. You probably don't want to jettison your wings.

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