Biogas-based hydrogen production and carbon dioxide removal: Techno-economic and climate impact assessment

Biohydrogen produced from biogas combined with carbon dioxide removal (CDR) can provide renewable energy whilst generating negative emissions. This study evaluates production costs and climate impacts of biogas-based hydrogen via steam methane reforming (SMR), electrified SMR (e-SMR), and plasma methane pyrolysis (PMP), together with CDR based on either CO 2 or solid carbon, across three production scales. Hydrogen production costs including CDR range from 6.0-11.8, 4.5-8.6, and 7.3-17.9 € kgH 2 −1 for SMR, e-SMR, and PMP respectively, but can decrease through carbon credit revenue. Although biogas plant integration reduces costs in decentralised systems, large-scale centralised systems achieve the lowest overall costs. Solid carbon from PMP applied in agricultural soil lowers CDR cost compared to geological CO 2 storage (1.3-12.1 and 203.0-299.0 € tCO 2 eq −1 stored, respectively), primarily by avoiding capture and shipping. All systems can achieve net negative emissions (−6.2 to −13.3 kgCO 2 eq kgH 2 −1 ) if low-carbon electricity is available.