Expanding production of renewable gaseous fuels is timely needed for decarbonization across sectors. Anaerobic digestion (AD) is a commercialized technology that utilizes biodegradable feedstocks to produce biogas or renewable natural gas (RNG), but its expansion is constrained by the limited conversion efficiency. This study proposes a novel integrated AD-Pyrolysis system to enhance fuel production from the limited resources, assessing its feasibility through a techno-economic-environmental analysis. This integrated system establishes a closed-loop approach, repurposing waste streams from both systems for use in the other. The overall methane yield is improved by incorporating solid digestate-derived biochar and treating aqueous pyrolysis liquid in the digester. Taking British Columbia, Canada, as a case study, the integrated system demonstrates greater greenhouse gas (GHG) reduction potential than a stand-alone AD system. Upgrading biogas to RNG is preferred over direct use in combined heat and power generation. The negative carbon intensity of RNG makes it economically beneficial from policy. The integrated AD-Pyrolysis system maximizes feedstock utilization, particularly for residual biomass with limited availability, while improving product efficiency to meet increasing demand. The insights on its decarbonization potential and economic viability can support regional decision-making for stakeholders.
