Techno-economic and sensitivity analysis of biomethane production via landfill biogas upgrading and power-to-gas technology

Power-to-gas system produces synthetic methane through two-step processes: H2 production via water electrolysis and methanation of CO2. The technology valorizes CO2 as a useful commodity from biogas plants. Biogas upgrading technologies have the capacity to capture CO2 and supply it as a source of carbon to methanation processes hence to produce synthetic methane. In this study, we have carried out a techno-economic assessment of biomethane production and estimation of its production costs via the integration of landfill biogas to methanation process. The study assessed four different scenarios, scenario 1: water-scrubbing, scenario 2: membrane, scenario 3: direct methanation and scenario 4: methanation with membrane. Production costs in case of power-to-gas scenarios 3&4 are competitive with standard upgrading scenarios 1&2 for electricity price below 20 €/MWh. Presence of electrolyzer unit contributes to more than 75% of the total biomethane production costs. Scenarios 1&2 are insensitive to changes in electricity prices as well as to operating time, but scenarios 3&4 are extremely sensitive to both electricity prices variation and operating time. Increase in the plant size and vol% of CH4 in raw biogas presented shorter payback period in case of scenarios 1&2 due to lower specific production costs.