Majority of methane emissions from European biogas plant supply chains could be eliminated at no net cost

Abstract Biogas, and its purified form – biomethane, offers substantial low-carbon energy potential, but uncertainties regarding methane emissions may undermine this benefit. This study addresses this uncertainty through a mixed-method emissions survey across three European countries, combined with environmental assessment, mitigation analysis and regional policy comparison. Our findings reveal that methane emissions from biogas production average 14.4 kg/h per site (5.4% of methane produced) with a range of 1.3-57 kg/h (2%-21.7%). These values exceed previous estimates, yet 59% of emissions could be eliminated at no net cost. When considering full supply chain emissions, methane emerged as the dominant greenhouse gas, accounting for 47% (18-93%) and 60% (34-94%) of greenhouse gases over 100- and 20-year time horizons, respectively. We advocate for EU and national policy revisions to better account for methane’s contribution and enhance emissions monitoring, highlighting the need for policy interventions incorporating recent advances in methane measurement and cost-effective mitigation strategies.