PNNL

Abstract

Microbial electrolysis cells (MECs) provide exciting opportunities to produce clean energy carriers such as hydrogen (H2) while degrading organic matter contained in wastewater. Various configurations and functionalities have been explored ever since MECs’ invention. Despite hundreds of MEC literature published so far, scaling up MEC remain a challenge due to the unique problems arose as the size goes up. It has been more than 10 years since the first scale-up MEC was built, and this review serves to look back on the scale-up efforts and summarizes what lessons we can learn from the past pilot MEC efforts. For the first time, we summarized the major scale-up configurations and systematically evaluated their performance . We discussed how different parameters were affected by the size effect and found that current related parameters, including volumetric current density and H2 production rate, were the most impacted by scaling-up. In order to improve the H2 production rate, surface area-based current density of pilot MECs need to be further increased. A preliminary techno-economic analysis shows that MECs can be profitable at many different price scenarios, although pilot MECs should aim for lower applied voltage and higher faradaic efficiency to make MEC economically viable. Lastly, we provide our perspectives on the research needs for scaling up MEC and envisioned the MEC research in the approaching era.