Cost-effective carbon-dioxide removal through water electrolysis and Oxy-BECCS integration

Abstract

This study investigates the integration of water electrolysis with biomass oxy-combustion and gasification for hydrogen (H₂) production and carbon dioxide removal (CDR) within a bioenergy with carbon capture and storage (BECCS) framework. As demand for clean H₂ grows to meet decarbonization goals, producing it with minimal emissions is increasingly critical. Oxygen (O₂) enhances combustion and gasification by reducing nitrogen dilution, improving thermal conversion efficiency, and facilitating CO₂ capture. Four configurations, atmospheric and pressurized combustion and gasification, are evaluated to assess the impact of process type and pressure on H₂ production, CO₂ capture, and electricity demand, highlighting trade-offs between conditions and costs.

All configurations achieve a net-negative emission system (Scope 1), with pressurized gasification delivering the lowest levelized cost of hydrogen (LCOH) at $3.91/kg H₂, a 21% reduction compared to the atmospheric combustion case, excluding CO₂ credits. Total capital investment (TCI) and cost of manufacturing (COM) are the lowest for combustion cases due to their simpler process design, requiring fewer equipment units and lower net electricity demand. Conversely, gasification configurations require syngas processing and compression, leading to higher capital and operating costs, however, these are offset by the near doubling of H₂ production. Sensitivity analysis reveals that CO₂ credits of up to $117 USD/tonne can reduce LCOH below standalone electrolysis. Additionally, electrolyzer-integrated O₂ consistently outperforms air separation unit (ASU)-sourced O₂ in cost-effectiveness across scenarios, highlighting the economic value of CO₂ credits in supporting net-negative H₂ pathways. Pressurized gasification is identified as the most cost-effective overall, while combustion is better suited to electricity- or capital-constrained applications.