Optimization of biomethane production from purified biowaste pyrolysis gas: A comparative techno-economic assessment

Abstract

This study investigates a novel pathway for biomethane production by converting biogenic residues into product gas through pyrolysis, water-gas shift reaction, and microbial methanogenesis. A key challenge in this process is gas purification, as the product gas must meet certain requirements for grid feed-in while ensuring economic feasibility. Unlike conventional biomethane production via anaerobic digestion in biogas plants, this approach enables the utilization of recalcitrant biogenic residues while minimizing process-immanent limitations. The research integrates gas purification with a techno-economic assessment, focusing on achieving a higher H₂/CO₂ ratio through CO₂ removal, thereby minimizing additional hydrogen demand. A unique case study demonstrates that expanding the process with a scrubbing unit reduces hydrogen procurement costs by approximately 51 %, achieving the lowest levelized cost of biomethane at 143 €/MWh. Sensitivity analysis reveals that hydrogen price is the most critical factor for economic feasibility, while electricity price has minor impact. The findings provide actionable insights for scaling biomethane production from biogenic residues via pyrolysis, offering a promising alternative to conventional biogas upgrading. The study highlights the crucial role of tailored gas purification strategies and recommends scrubbing units as a key component for future industrial applications.