http://www.sciencemag.org/content/334/6058/935
The solid oxide fuel cell (aka "Bloom Box") is a bit of a mystery of efficiency - even with units in mass production. With the HotCat demonstrating surprising temperature possibilities - direct conversion is on the horizon and one wonders if the SOFC is adaptable as a non-combustion converter of heat to electricity using oxygen from air as the charge carrier (looped)? There are other possibilities as well. In the SOFC, a high temperature ceramic (zirconia based) - which is non-porous - is used as the "fast ion electrolyte" and oxygen is the charge carrier. This seems implausible at first to anyone who is unaware of the technology - that oxygen ions instead of the much smaller and more mobile protons would be an efficient charge carrier in such a converter. Recently, solid oxide fuel cells have demonstrated high power densities of about 2 watts per square centimeter at 650°C and conversion efficiency of over 50% thermal-to-electrical. A sleeve of SOFC material of a size that would enclose the HotCat could potentially convert 6 kW of thermal power, derived from 1 kW of self-generated electricity - into 3 kW of electrical, with up to 2 kW to spare - if a substitute for combustion via a substitute were available. Riiiiight... in an optimist's dreams it could. Anyway, SOFCs rely on combustion to effectively provide the emf to "pull" the hot oxide ions from one side of the ceramic to the other. Thus, there is an effective pressure involved - and we must ask - is heat combined with externally applied pressure enough to "push" the same hot oxide ion in an inverted SOFC? After all, the proton provides only about 1.25 eV of emf, and on paper the band gap of many semiconductors could provide that, or else a triode grid combined with mechanical pressure. If an extra kW is required for pumping (the oxygen in a closed loop) or grid losses, there is still some to spare. Even so - the reflexive answer to a possible combustion substitute is "no-way" - even with losses .... but then again, the reflexive answer to whether a reaction of nickel and hydrogen can provide 6 times more energy than combustion is also no. "Closing the loop" is likely to be the only way that many skeptics, the ones in deepest denial, will be swayed. Jones Brick: What is the victory of a cat on a hot tin roof? Maggie: Just staying on it, I guess...
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