[AR] Re: That nasty carbon again...
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 7 Jul 2021 16:15:25 -0400 (EDT)
On Wed, 7 Jul 2021, Valtteri Maja wrote:
Is there something fundamental that makes fuel cells heavy for their
power? Something like that the reaction has to happen on a surface vs in
a volume for internal combustion?
The surface aspect doesn't help, but I think the biggest issue is not so
much the fuel cells in particular, as the problems of handling the energy
as electricity. It's a huge dry-mass advantage to have the energy
released in the same gas that's going to be used as the expansion medium
to convert that energy into mechanical motion, because then the engine
hardware never has to *handle* most of that energy. Turbine engines don't
benefit from this as much as rockets (a rocket engine the size of a big
desk can be a gigawatt machine), because they've got to capture and handle
some of that energy to drive their compressors, but they're still way
ahead of systems that have to handle all of it.
Henry
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