Sustainable and Efficient Biohydrogen Production via Electrohydrogenesis

In response to the pressing challenges of the energy crisis and global warming, the imperative for transitioning to sustainable energy sources has never been more urgent. Fossil fuels, with their finite supply and detrimental environmental impacts particularly the emission of carbon dioxide, underscore the necessity for change. Hydrogen emerges as a promising alternative, yet its predominant derivation from fossil fuels highlights the critical need for several sustainable production processes, including electrolysis of water, thermocatalytic reformation of hydrogen-rich organic compounds, and biological processes. Biological productions of hydrogen technologies demonstrate a wide spectrum of approaches to evolve molecular hydrogen, including MECs (microbial electrolysis cells), biophotolysis, photo and dark fermentation. Electrohydrogenesis, a revolutionary electrolytic technique, offers a sustainable approach by harnessing specific exoelectrogenic bacteria through a microbial electrolysis cells (MECs). MECs emerged as an innovative technology harnessing the power of the microorganisms to evolve hydrogen and other valuable chemicals from renewable sources. These technologies illustrate a convergence of electrochemistry, microbiology, and engineering, offering distinct advantages, including lower energy inputs, higher conversion efficiency, and alternatives to traditional energy-generating methods in the current global energy scenario. The present chapter elucidates the basic principle, operational parameters, electron transfer mechanism, overcoming microbial limitations, crucial factors influencing MEC performance, key confronting challenges for practical applications, emerging approaches, and advancements in MECs. Current article underscores the potential of sustainable hydrogen by addressing various associated factors influencing environmental optimizations and genetic modifications, application of diversifying feedstocks, electrodes systems, and mitigating methanogenic consumption during its operational spectrum. The contemporary and upcoming challenges in MECs technology also include the integration with MFCs (microbial fuel cells) in hybrid MEC–MFC systems to reduce external energy inputs during MEC operations. Such technological advancement in energy sector plays a pivotal role in a circular economy that leads to reshaping greener energy routes with rapid possibilities for commercialization.