Potential of biohydrogen production from dark fermentation of crop residues and its contribution to carbon emission reduction in China

Biohydrogen production (BHP) from biomass provides an essential perspective for realizing the carbon-hydrogen cycle and green hydrogen production. This paper estimated the potential BHP from dark fermentation of crop residues and its contribution to energy and carbon emission reduction in China. The available crop residues yield (rice, wheat, maize, yam, beans) was 4.7 x 108 t/a for BHP in 2019. This could correspond to 301.45 x 108 m3/a of BHP, equivalent to 11.48 % and 1.95 % of China's natural gas and coal consumption in 2019. The total greenhouse gas emissions mitigation would be about 94.33 x 106 t/a (CO2 equivalent), accounting for -1 % of China's annual GHG emissions. The highest contributor is maize residues, accounting for -0.5 %, followed by rice and wheat residues. The present results provided valuable guidance on exploiting crop residues for bioenergy refining and assisted in the realization of carbon emission reduction.