Biohydrogen 2.0: Emerging Innovations from Waste Valorisation to Intelligent Bioprocess Design

The growing requirement for sustainable energy, coupled with greenhouse gas emissions reduction, have resulted in increased research efforts towards the production of hydrogen via biohydrogen as an alternative to fossil fuels. Biohydrogen production methods, though environmentally friendly, have limitations in terms of hydrogen yield and other operational issues. The objective of this literature review is to introduce Biohydrogen 2.0 and discuss recent advancements which make biohydrogen production technologically feasible for its incorporation into future energy generation. Special focus will be paid to biohydrogen production using WV approaches through utilization of crop residues, food wastes, industrial effluents, sewage sludge, algae biomass, and new waste sources as sustainable feedstock. Additionally, novel approaches like ME, synthetic biology, microbial consortium engineering, nanobiotechnology-enabled bioprocessing, and DF-PF and microbial electrolysis cell hybrids are also explored. Recent developments in hybrid and MEC-assisted systems have demonstrated higher hydrogen yields than conventional DF, which typically produces approximately 2–4 mol H2 per mol glucose, with some integrated systems achieving up to 5.2 mol H2 per mol hexose-equivalent substrate under controlled conditions. In addition, the combination of AI, machine learning, digital twins, and advanced reactor engineering is making huge changes to process optimization with predictive accuracy rates exceeding 95%, coupled with operational savings of 40%. Overall, the combination of biotechnology, digitization, and the circular bioeconomy approach can pave a way towards effective biohydrogen production.