From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Fri Jun 04 1999 - 14:45:21 MDT
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.
> 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.
> 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.
> 50% of the bond energy due to reforming a fuel to hydrogen, we get better
> overall efficiency with the fuel cell. I just get itchy when ANY energy
> gets thrown away without a chance to do work.
>
> If I recall right, large methane fueled fuel cells were proposed for
> installation in New York City to generate power - and the waste heat could
> then be used for process or building heat. Does anyone know if this scheme
> was actually installed?
>
> Chuck Kuecker
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