SOLID OXIDE FUEL CELL - SOFC
Solid oxide fuel cells work at very high temperatures, the highest of all the fuel cell types at around 800ºC to 1,000°C. They can have efficiencies of over 60% when converting fuel to electricity; if the heat they produced is also harnessed.
Its overall efficiency in converting fuel to energy can be as much as 82%.
SOFCs use a solid ceramic electrolyte, such as zirconium oxide stabilised with yttrium oxide, instead of a liquid or membrane. Their high operating temperature means that fuels can be reformed within the fuel cell itself, eliminating the need for external reforming and allowing the units to be used with a variety of hydrocarbon fuels. They are also relatively resistant to small quantities of sulphur in the fuel, compared to other types of fuel cell, and can hence be used with coal gas.
A further advantage of the high operating temperature is that the reaction kinetics are improved, removing the need for a metal catalyst (similar to MCFC). There are however some disadvantages to the super high temperature: SOFC cells take longer to start up and reach operating temperature, it must be constructed of robust, heat-resistant materials, and it must be shielded to prevent heat losses.