Thermodynamic Analysis of a Single Chamber Microbial Fuel Cell

Microbial fuel cells (MFCs) are devices that utilize bacteria to generate renewable electricity energy from organic compounds. Most of the current research performed on MFCs is concerned with increasing the power density of the system with respect to the peripheral anode surface area; little research has been done on determining the effects of voltage output, and second law thermodynamic efficiencies in comparison to varying fuel cell components and structures. Seven single chamber MFCs were fabricated and tested with primary effluent domestic wastewater sample under permitance from the City of Arcata, CA. The direct current (dc) voltage potential data obtained from these MFCs was used to compute second law thermodynamic efficiencies ranging from 7.27% to 33.6%. An environmental and economic analysis determined a theoretical large scale capital cost as $20,830,000 with projection costs of 10, 20 and 30 years based on a 5% discount rate and a theoretical carbon emission offset of 841 kg C/year. Investigation concluded that a proper biofilm is needed to obtain desirable voltage results and further analysis will investigate double layer issues and internal resistance properties using an Electrochemical Impedance Spetrometry (EIS) technique.

Keyword: MFC (*) Corresponding author E-mail: eaz4@humboldt.edu