Hydrogen production from switchgrass via an integrated pyrolysis–microbial electrolysis process

• Demonstrated conversion of switchgrass-derived bio-oil aqueous phase to hydrogen.
• Enriched anode community capable of simultaneously converting inhibitory compounds.
• Achieved hydrogen production rate of 4.3 L H2/L-day using biomass-derived liquids.
• Long-term operation with high Coulombic, conversion and overall energy efficiencies.

A new approach to hydrogen production using an integrated pyrolysis–microbial electrolysis process is described. The aqueous stream generated during pyrolysis of switchgrass was used as a substrate for hydrogen production in a microbial electrolysis cell, achieving a maximum hydrogen production rate of 4.3 L H2/L anode-day at a loading of 10 g COD/L-anode-day. Hydrogen yields ranged from 50 ± 3.2% to 76 ± 0.5% while anode Coulombic efficiency ranged from 54 ± 6.5% to 96 ± 0.21%, respectively. Significant conversion of furfural, organic acids and phenolic molecules was observed under both batch and continuous conditions. The electrical and overall energy efficiency ranged from 149–175% and 48–63%, respectively. The results demonstrate the potential of the pyrolysis–microbial electrolysis process as a sustainable and efficient route for production of renewable hydrogen with significant implications for hydrocarbon production from biomass.

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