The huge volumes of crop residues generated during the production, processing, and consumption of farm products constitute an ecological nuisance when ineffectively managed. The conversion of crop residues to green hydrogen is one of the sustainable management strategies for ubiquitous crop residues. Production of green hydrogen from crop residue sources will contribute to deepening access to clean and affordable energy, mitigating climate change, and ensuring environmental sustainability. However, the deployment of conventional thermochemical technologies for the conversion of crop residues to green hydrogen is costly, requires long residence time, produces low-quality products, and therefore needs to be upgraded. The current review examines the conventional, advanced, and integrated thermochemical conversion technologies for crop residues for green hydrogen production. After a brief overview of the conventional thermochemical techniques, the review delves into the broad narration of advanced thermochemical technologies including catalytic pyrolysis, microwave pyrolysis, co-pyrolysis, hyropyrolysis, and autothermal pyrolysis. The study advocates the deployment of integrated pyrolysis, anaerobic digestion, pyrolysis, and gasification technologies will ensure scalability, decomposition of recalcitrant feedstocks, and generation of high grade green hydrogen. The outlook provides suggestions for future research into cost-saving and sustainable integrated technologies for green hydrogen production towards achieving carbon neutrality and a circular bio-economy.
Awogbemi et al. (Tue,) studied this question.