From: Michael S. Lorrey (mike@lorrey.com)
Date: Fri Jun 04 1999 - 15:27:03 MDT
Eugene Leitl wrote:
> Chuck Kuecker writes:
>
> > Looks to me that all current fuel cells work only with hydrogen - the
>
> No, you _can_ use alcohols, especially methanol in low temperature
> cells. People have recently been talking about using alcohol fuel
> cells to power portable computers. Interesting how this would compare
> to MEMS microturbine generators, powered by butane.
>
The turbines that the Army is testing for use by infantry are something like 10
watts per cubic inch. I wonder how the will compete with those new radioactive
powder plasma/dielectric batteries which supposedly have phenomenal power
densities.
> > carbon bonds, if any, are wasted as CO2 without contributing to the
> > electrical output. Perhaps in the high temperature cell, this energy helps
>
> In a way, the energy is not wasted. Fuel reforming is supposed to work in the
> following way:
> CH4+2H2O->catalyzed reforming->CO2+4H2
>
> This is how the bulk of hydrogen is produced today. CO2 are scrubbed
> using organic bases -- for high purity the gas can be passed though a
> heated Pd/Ag alloy membrane, which is selective to hydrogen.
I though the reformation process preferred producing carbon monoxide. Maybe I'm
thinking of the old coal reformation process...
>
>
> > Fuel cells are about 50% efficient, if I recall rightly - so even losing
>
> Oh, a non-production room temperature cells could have well
> beyond 90%. And electrical motors with 98% efficiencies are not
> unheard of. Notice that Carnot machines will never make more
> than 37%. A real-world car does much, much worse.
Actually, current econo-speck car engines are at least 46% efficient, but the
transmission and rolling and aerodynamic drag will drop it down to the 14-24%
efficiency range. Even an electric car, all told, has a 30-45% efficiency.
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