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Researchers Seek to Optimize Lower-Temperature SOFCs for Biofuels

Researchers at the University of Virginia are working to use nanoscale structures to develop lower-temperature solid oxide fuel cells optimized for the direct use of biofuels.

The team led by Assistant Professor Steven McIntosh will attempt to increase the speed and efficiency of the ion reactions in the SOFC to enable operate at lower temperatures (500°C rather than 800°C), making them more stable and longer lasting.

The goal is a fuel cell that can produce 10,000 hours of electricity to be used in a new type of small power plant, which would provide enough power for a small town or even a city block.

The research is supported with part of a $30,000 U. Va. Collaborative Sustainable Energy Seed Grant. The other part of the grant is supporting the development a new solar-cell for water-splitting, using similar nanostructures.


Healthy Breaze

So, I always thought a big part of the appeal of SOFC was that they are very efficient and could run on a wider range of fuels than PEMFC and the like. That makes them attractive for running on wet ethanol, biodiesel, or whatever turns out to have the best well-to-wheel efficiency, as it were.

Question: If you reduce the temperature at which SOFC will run, do you lose some of the fuel flexibility?

yes as long as the operating temperature is above the point where the delta G for the auto reforming of the fuel reaction is negative then the reaction will happen. Thermochemical reactions are temperature sensitive increasing temperatures usually drive the reactions to the left being product favored. The kinetics of the reaction are temperature, pressure and concentration of the products vs reactions dependent.Any Chem II student can run the calculations on a SI calculator 500'C is still 723K pretty high in absolute terms. most Autoreforming reactions for common fuels should still happen at 700+'K the longer hydrocarbons like JP8 or Diesel might start to have issues but all of the lighter hydrocarbons, alcohols should still work. Now where is my old Chem II book...


Actually, at lower temperatures the conversion to combustion products (CO2, H2O) should be more complete and the difference in oxygen-ion concentration across the cell should be higher.  That would yield greater efficiency.

The expanded choices of materials, reduced thermal stresses, etc. are probably more important than slight improvements in reaction kinetics, I suspect.

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