Thermodynamic analysis of biohydrogen and microbial fuel cells

A thermodynamic analysis is performed based on the free energy of reaction for the different approaches, which included methanogenesis, with combustion of the methane to generate electricity; biohydrogen production using a fermentative process combined with methanogenesis; biohydrogen production using a fermentative process combined with a second H ₂, which is converted to electricity with a fuel cell; biohydrogen production using a fermentative process combined with a microbial fuel cell (MFC); and direct generation of electricity using a MFC. On the basis of ideal voltage output for a MFC, glucose is the most ideal fuel source with the highest voltage output of 1.24 v. The observed voltage output of MFC is 0.475 and 0.6 v. Biohydrogen production with conversion of the H ₂ to electricity in a conventional fuel cell is intermediate between the fuel-cell options and methanogenesis. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).