Biohydrogen and biomethane production from biomass gasification: Compositional analysis, recent advancements, challenges, and prospects

Renewable fuels such as biohydrogen and biomethane are vital in reducing greenhouse gas emissions and fulfilling energy demands. These biofuels are the main products of the biomass gasification process. Review studies have shown a large number of experimental works performed in recent years to enhance biohydrogen and biomethane production process performance. A few process systems engineering-based reviews have also been published, mainly focusing on production technologies. However, detailed literature review assessments of biohydrogen and biomethane production from biomass gasification, considering both experimental and process systems engineering studies, are not available in the open literature. Here, we investigated biohydrogen and biomethane-focused experimental works and process systems engineering studies considering feed and product specifications, process parameters, and process performances. Additionally, the factors influencing the composition of biohydrogen and biomethane, including pressure, temperature, and gasifying agents, are also discussed. The results show that biomass gasification using water at super-critical conditions improves the biohydrogen and biomethane composition in the product gas. Experimental studies indicate that wood-based biomass sources produce biohydrogen (∼82 vol%) and biomethane (∼10 vol%) rich syngas. The process systems engineering studies indicate energy efficiency (∼67 %) in gasification processes, suggesting further improvement potentials. Integrating other processes and employing a feedstock mix can improve gasification process efficiency. This study can help develop a sustainable, cost-effective, environmentally benign, and energy-efficient biomass gasification process.