Techno-economic assessment on bio-dimethyl ether production from a landfill biogas in Spain: a comparison between direct and indirect routes

Herein we propose two bio-DME production configurations from landfill biogas produced by a real company located in Sevilla, Spain. The purpose of this paper is to shed light on real cases of landfill biogas-to-bio-DME profitability studies, which are scarcely reported, and can be of great interest as renewable fuels. The processes studied are (i) direct bio-DME route, where bio-MeOH synthesis and its dehydration occur in a one-step reacting stage, and (ii) indirect bio-DME route, with bio-MeOH synthesis and purification taking place prior to bio-DME synthesis. Technical modelling is conducted with Aspen Plus® software including the Pitch point heat integration strategy. The economic outcome is estimated for a 20-year lifespan project with three key parameters: Net Present Value, Profitability Index and Minimum Selling Price. Simulation results include 249.2 kg bio-DME /h (99.7% purity) along with 34.4 kg bio-MeOH /h (99.5 wt% purity) for the direct route, and 244.7 kg bio-DME /h (99.6% purity) plus 37.8 kg bio-MeOH /h (99.6% purity) for the indirect route. Moreover, CO 2 avoidance is in line with previous works, reaching up to 0.61 kg bio-DME /kg CO2 for the direct DME route. Regarding the economic aspect, the Net Present Value is positive for bio-pricing of DME and MeOH, while strongly negative profit results for the indirect conversion to DME under fossil commercialization. MSP bio-DME range of 0.95 to 1.35 €/kg bio-DME is reported. Sensitivity analysis reports high influence of biogas flow and composition variations on final bioproducts’ quality and strong profitability fluctuations with heating requirements. This research gives valuable insight into circular economy principles, fostering the great potential of biogas-based DME synthesis under current landfill infrastructure for its potential utilization as alternative fuel.