Techno-economic assessment of renewable dimethyl ether production pathways from hydrogen and carbon dioxide in the context of power-to-X

Dimethyl ether (DME) is an emerging alternative to traditional diesel and LPG as a power-to-X product. This study employs kinetic models to simulate potential DME production routes, assessing key technical and economic performance indicators for comparison. Aspen Plus, a commercial process flowsheet simulation tool, is used alongside Pinch methodology for heat integration. Four production routes are examined: two direct, converting feed gas directly to DME, and two indirect, involving methanol as an intermediate step. For one case in each, CO₂ is initially converted to CO via the reverse water gas shift process (rWGS). Post heat integration, all routes exhibit higher cooling demand, with significant energy savings, notably in the indirect pathways. Indirect routes achieve power-to-fuel efficiencies of up to 39.6%, considering electrolysis and carbon capture. Direct routes excel in carbon conversion efficiencies, reaching 92.6%. Economically, indirect routes have higher upfront costs but lower operational expenses due to better energy efficiencies. Direct CO₂ conversion yields the lowest levelized manufacturing costs at 2.45 €/kg, closely followed by the indirect route with rWGS. Further research is needed to enhance kinetic models and reduce simulation result uncertainty for direct conversion.