Converting methane into electricity and higher-value chemicals at scale via anaerobic microbial fuel cells
Thomas K. Wood, Ilke Gurgan, Ethan Howley, Ingmar H. Riedel‐Kruse
Abstract
Methane (CH4) is the second most damaging greenhouse gas by absolute amounts released. Many globally distributed methane sources are of human origin, representing a significant untapped potential for capture and on-site conversion into electricity or ‘higher value’ chemicals. This study systematically and quantitatively analyzes the anaerobic oxidation of methane (AOM) in microbial fuel cells (MFCs) for generating electric power as well as analyzes AOM in bioreactors for producing value-added chemicals. The maximum performance of such systems is currently unknown. Based on biophysical arguments, power densities of 10 kW/m3 and more should be achievable, and Coulombic, carbon conversion, and energy conversion efficiency could reach 90%. Such performance is much higher than what is usually predicted. This AOM MFC approach promises higher efficiency, scalability, cost-effectiveness, and easier distribution compared to existing chemical plants or aerobic biological approaches. Yet achieving this requires significant and integrated advancement of different technologies. This analysis provides an accessible primer for the necessary interdisciplinary research effort, and discusses recent enabling biotechnological advancements, open research questions and corresponding R&D pathways, where enzyme and synthetic microbial consortia engineering, microfluidic technologies, membrane and electrode materials, modular system integration, and power optimization technology will likely be critical. In conclusion, AOM MFC is a very promising technology as the performance limits estimated here show, and if realized at scale, a significant impact on green-house gas reduction and sustainable, on-demand electricity and chemical (fuel) production could be achieved; this analysis could also aid the rational MFC design for other chemical reactions.