The requirement of energy in one form or another is important for all human activities. The U.K. Energy Research Center reported that the production of oil will reach its peak in 2030, and after that, it will start to decline (Sorrel et al. 2010). Similarly, the production of gas reaches its peak in 2020 (Bentley 2002). Further rise in global temperature results in melting glaciers and rising sea levels (Kerr 2007; Voiland 2009). Hence, the search for alternative renewable energy sources is facilitated (Faaij 2006; Rodrigo et al. 2007). The renewable energy sources are based on solar, wind, tidal, bio, piezoharvester, and fuel cells (Tsuneo 2001). Presently, biofuels such as ethanol from starch or sugarcane and biodiesel from vegetable oil or animal fats are widely used (Fortman et al. 2008). However, ethanol is not a better fuel, because it is not compatible with the present fuel transportation suchCONTENTS25.1 Introduction 557 25.2 General Principle and Techniques of MFCs 55825.2.1 Principle 558 25.2.2 Materials of Construction 56125.2.2.1 Anode 561 25.2.2.2 Cathode 561 25.2.2.3 Catholyte and Anolyte 561 25.2.2.4 Membrane 56225.2.3 MFC Design 563 25.2.4 Characterization Techniques for MFCs 566