Comparative economic and environmental performance assessment of biomass gasification pathway for green H2 production

The transition to low-carbon energy sources is essential to limit the temperature rise due to global warming. Biomass is a carbon-neutral source of energy that could aid in the energy transition and decarbonisation goals. This work compares the economic and environmental performances of small-scale (100 kg/h output) green hydrogen [biomass gasification (BG) and water electrolysis (WE)] pathways, using commercial-scale (20 tph output) conventional hydrogen [steam methane reforming (SMR)] as reference. The source of the electricity supply for BG system operations is a major determinant of the life-cycle emissions. It could be sourced externally (grid) or generated in-situ through an auxiliary gasification system. Capture of CO2 from the syngas stream is feasible through a vacuum pressure swing adsorption (VPSA) unit. The assessment reveals negative specific carbon emissions (up to -19 kg CO2/kg H2) when electricity is generated in-situ and carbon capture is carried out in BG systems. The hydrogen costs from the BG pathway are in the range of INR 307-352/kg ($3.71-4.27/kg), competitive with water electrolysis using solar power. The study also suggests the introduction of emission reduction incentive (ERI) as a combined economic-environmental performance indicator. Among the green pathways, BG-H2 with in-situ electricity generation and carbon capture has the best combined performance, requiring an incentive of $127/tonne CO2. While commercial-scale SMR has a low hydrogen production cost due to economies of scale, the increasing natural gas prices could make the BG-H2 pathway lucrative in the future.