Science Buddies: "Ask an Expert"

How are solid oxide fuel cells kept at the high temperatures required for them to operate? If they use heat from an engine, does that mean a car couldn't be powered solely by solid oxide fuel cells? Or if it could (i.e. the engine powered by the SOFC generates heat, which keeps the SOFC at the right temperature) how would the car get started? In my mind, the engine would have to run before the SOFC could start generating electricity, to get it to the right temperature. And that would mean the car could never run without an outside power source.

PEMFCs run at about 60-80 degrees C, and not above 100. Even 60 degrees is much higher than room temperature. So, for that matter, how are PEMFCs kept at the temperature required for them to run?

Thanks
candy4me

I don't know that much about fuel cells, but from what I can tell by looking around the internet, it appears the SOFC's started up by applying external heat, and that the process takes around an hour to do smoothly to avoid damaging the cell. It's probably not too suitable for a car power source for that reason, though there's some evidence that people are working on something called "micro-tubular fuel cell design" that has a start up time on the order of minutes (that might still be too long for a car in a practical sense).

The problem with PEMFCs appears to be more cooling than keeping it hot, as they generate as much heat as they do electrical power. Exactly how that's started up isn't clear to me, but it appears that the 60 degree temperature is its efficient range, not that it's necessary for them to work at all.