Critical factors influencing biohythane production from research to commercialization

The shift from fossil-derived energy to clean, renewable sources has accelerated due to the demand for sustainable and commercially viable energy solutions. Another possible clean fuel is biohythane, also known as HCNG, which is a blend of bio–CH₄ and bio–H₂ with a concentration of 10 and 30 % v/v, respectively. The chemical industries have eventually been utilizing bio–CH₄ and bio–H₂ extensively because of their high calorific values of 143 and 55 kJ g⁻¹, respectively. The bio–H₂ and bio–CH₄ have been emerged as promising green energy carriers, offering a broad range of applications in chemical industries, owing to their high calorific value, renewability, and CO₂ neutrality. In the pursuit of zero-emission technologies to mitigate the global warming, biohythane is gaining attraction as a potential future fuel. This study explores biohythane production through a sequential two–stage process that converts organic wastes into bio–H₂ and subsequently into bio–CH₄, offering an ideal pathway for sustainable biohythane generation. Further, this study provides an overview of key developments and applications in two–stage microbial synthesis of bio–CH₄ and bio–H₂, alongside insights into the demand, supply, and current global status of biohythane production. This study delves into the acidogenic phase, where bio–H₂ is produced, and the methanogenic phase, which yields bio–CH₄. While detailing the biochemistry, critical factors, challenges, and limitations of an integrated bio–hythane production system are discussed. Finally, the strategies for enhancing bio–H₂ and biohythane production and an outlook on their commercialization potential are discussed.