Techno-economic analysis of bio-methane production from agriculture and food industry waste

Bio-methane production via anaerobic digestion is a promising technology for the decarbonization of the energy system. Bio-gas obtained from anaerobic digestion of farm and food industry waste is largely composed of 60% CH4 and 40% CO2. For injection of bio-methane into the gas distribution network it is necessary to remove CO2 from the biogas so that a richer CH4 stream is injected to satisfy gas network requirements. Chemical separation processes using solvents that react with CO2 or physically processes using adsorbents or membranes in which CO2 is retained are currently under investigation to reduce associated energy consumption whilst maximizing CO2 removal. In the case of sorbent based processes, research is mainly focused on the optimal design of pressure swing adsorption (PSA) cycles. In this work, a comparative techno-economic study of bio-gas upgrading for bio-methane production using solvent based processes and pressure swing adsorption cycles is presented. The results show that, pressure swing adsorption cycles exhibit 37% lower capital costs and 10% lower average life-time costs compared to solvent based technologies.