Optimal year-round production of DME from CO2 and water using renewable energy

• CO2 can be useful as carbon source to produce chemicals and store solar and wind energy.
• DME is produced using CO2 and electrolytic hydrogen from water.
• Mathematical optimization is used to systhesize the flowsheet and determine the operating conditions.
• Solar energy is preferred in South Europe as energy source.
• Biomass is more efficient in CO2 capture and less expensive.

In this paper we present the optimal year round production of DME from electrolytic hydrogen and and CO2. Solar PV systems and wind turbines are compared as sources of energy for water electrolysis. The process comprises a wind farm and/or a solar field, electrolyzers, gas stream purification stages, DME synthesis and purification. The unconverted gas can be recycled or used to produce power. Mathematical programming techniques are used for the design of the process and its optimal operation over a year. We present a detailed case of study in the south of Europe, Gulf of Cádiz. Solar energy and unreacted gas recycle are selected for the production of 197 kt/yr of DME at a production cost of 1.4€/kg and with an investment of 125M€. However, the production of DME over other chemicals such as methanol or methane is not a straightforward decision. Finally, up to date, biomass as a CO2 capture technology is more efficient and cost effective for the production of DME.