Flowsheet analysis of bio-derived hydrogen as a surplus product at sugar mills and associated biorefineries from processing residues

Abstract

The novelty was to investigate the self-sufficient integration of bio-derived H2 production at a sugar mill from lignocellulosic residues that is available at 65 tonne/h, using gasification OR anaerobic-digestion with biogas-reforming (ADR) that may include vinasse generated from an annexed ethanol distillery. Thus, the optimal use of lignocellulosic residues should ensure a steam supply of 120 tonne/h to the sugar mill, while also optimising the production of H2. Overall process economic costs were evaluated with the minimum selling price of H2 (MSPH). Thus, gasification processes may have produced 2566 kg/h of H2 at the lowest cost of 6.9 US$/kg, and ADR may have produced 2067 kg/h of H2 at 7.7 US$/kg from lignocelluloses that underwent steam-explosion. Otherwise, annexing ethanol production could allow an H2 selling price under 5 US$/kg, if ethanol trades above 1.6 US$/kg. Generally, the milling season limited the annual H2 production, and hence the annual economic returns.