gets accumulated at the landfills has the potential to be a valuable source of energy since methane is a major constituent. Currently, the majority of the landfills either burn away their gas in flares or combust it in mechanical engines to produce electricity. The issue with mechanical engines is that incomplete combustion of gasses can lead to pollution of the atmosphere and is also highly inefficient. The issue with using landfill gas to fuel an SOFC system is that landfill gas contains hydrogen sulfide. Any landfill accepting biological waste will contain about 50-60 ppm of hydrogen sulfide and around 1-2 ppm mercaptans. However, construction materials containing reducible sulfur species, principally sulfates found in gypsum-based wallboard, can cause considerably higher levels of sulfides in the hundreds of ppm. At operating temperatures of 750 °C hydrogen sulfide concentrations of around 0.05 ppm begin to affect the performance of the SOFCs. Ni + H2S → NiS + H2 The above reaction controls the effect of sulfur on the anode. This can be prevented by having background hydrogen which is calculated below. At 453 K the equilibrium constant is 7.39 x 10−5 ΔG calculated at 453 K was 35.833 kJ/mol Using the standard heat of formation and entropy ΔG at room temperature (298 K) came out to be 45.904 kJ/mol On extrapolation to 1023 K, ΔG is -1.229 kJ/mol On substitution, Keq at 1023 K is 1.44 x 10−4. Hence theoretically we need 3.4% hydrogen to prevent the formation of NiS at 5 ppm H2S. See also Auxiliary power unit Bloom Energy Server – SOFC product from an American company Ceramic Fuel Cells Ltd – Australian company producing solid oxide fuel cells Glossary of fuel cell terms Hydrogen technologies Micro combined heat and power References External links US Department of Energy page on SOFCs National Energy Technology Laboratory website on SOFCs An article in Encyclopedia at YCES Illinois Institute of Technology page on SOFCs Assessment of Solid Oxide Fuel Cells in Building Applications Phase 1: Modeling and Preliminary Analyses CSA Overview of SOFCs SOFC glass-ceramic sealing Refractory Specialties Inc. Materials & Systems Research, Inc.'s (MSRI) Solid Oxide Fuel Cells Canada (SOFCC) Strategic Research Network SOFC Dynamics and Control Research Solid State Energy Conversion Alliance (SECA) Fuel cells ko:연료전지#고체산화물 연료전지 (Solid Oxide Fuel Cell, SOFC) ja:燃料電池#固体酸化物形燃料電池 (SOFC)