Microbial Electrolysis Cells for Sustainable Hydrogen Production from Waste Streams

Hydrogen gas (H2) is an environmentally sustainable and efficient automotive fuel, which has historically been produced from non-renewable fossil fuel-based resources. Over the past few decades, renewable resources have been used for H2 production via several technological approaches (i.e., electrochemical, photochemical, thermochemical, and biochemical technologies). Among those technologies, microbial electrolysis cells (MEC) show promise for sustainable H2 production from low-grade organic waste streams. This book chapter primarily covers fundamental concepts, necessary components, and potential integration of MECs with other bioelectrochemical systems for improving H2 generation from wastewater. In addition, we examine the challenges associated with energy harvesting and the economic implications of the gathered energy in depth. In a typical MEC, microbial activity occurs at the anode, whereas H2 evolution takes place at the cathode. The scaling up and real-time applications of MECs are mostly determined by reactor architecture and microbiology. The scalability of MECs needs to be elucidated in the near future to enhance H2 production and attain the United Nations Sustainable Development Goals (UN SDGs).