To ensure energy security and meet climate protection targets, Germany plans to import large quantities of hydrogen in the future. A promising energy carrier for hydrogen and its derivatives is the environmentally friendly, non-toxic, efficient, and economically attractive gas dimethyl ether (DME). The Fraunhofer Institute for Solar Energy Systems ISE has developed a new, particularly energy-efficient synthesis process for its production, which could become a game-changer for DME production and thus for the hydrogen economy. Based on this, the international “Power-to-MEDME” project investigated the entire process chain for large-scale production of methanol and DME in Chile.

“Dimethyl ether is the hidden champion of the hydrogen economy”

“Dimethyl ether is the hidden champion of the hydrogen economy, not only because it has a significantly higher volumetric energy density than ammonia—which has been the most commonly used substance to date—and is therefore an ideal candidate for import. It also serves as a renewable alternative to fossil feedstocks in sectors such as the chemical industry and the transportation sector as a platform molecule,” explains Dr. Elias Frei, Head of the Hydrogen Division at Fraunhofer ISE. The institute therefore aims to drive new DME applications and market developments in a new priority research area in collaboration with industry, enabled by current research findings.

The DME market will grow many times over

The DME market, which currently already amounts to more than five million tons per year, will grow many times over due to new applications (such as blending into liquefied petroleum gas [LPG] and as a platform molecule for fuels). “The global LPG market amounts to about 200 million tons per year. Added to this is, among other things, the market for the production of sustainable aviation fuels, which is estimated to reach up to 400 million tons per year by 2050. This demonstrates the enormous potential of DME,” explains Dr. Achim Schaadt, Head of the Sustainable Synthesis Products Department.

New Process Revolutionizes Production

DME is not an unknown gas: Many are familiar with it as a propellant in deodorants, and it is already used as a solvent and refrigerant. However, DME is currently produced via a complex and energy-intensive process, which reduces the overall efficiency of converting renewable energy into DME. This is where the INDIGO process developed at Fraunhofer ISE comes in: by combining synthesis and distillation, the process is greatly simplified, which increases efficiency and reduces costs by more than a quarter compared to the conventional DME synthesis process. The process requires less energy because the heat released by the reaction flows directly into the distillation column—as a low-energy process, it is particularly well-suited for remote regions. In the importing country, DME can then be split back into hydrogen with maximum yield, for example, via steam reforming. The “Power-to-MEDME” research project demonstrated that in all six cases analyzed, the INDIGO process is more cost-effective than the conventional reference. The Syn2X tool was used to simulate the processes and the process chain. This allowed for the modeling of the dynamic, partial-load-capable operation of the methanol plant, thereby yielding practical operating data under fluctuating load conditions.

DME Production Planned for Chile

The international research project “Power-to-MEDME” aims to tap into Chile’s potential for producing CO2-neutral energy carriers using the new INDIGO process. The prerequisites for this were established in this project. The next step is the construction of a pilot plant for the production of green methanol and DME on a megawatt scale. The research team is supporting this project through analyses of all process steps as well as material development and testing. The goal is to further reduce costs by increasing efficiency and optimizing the integration of various individual processes.

More efficient use of electricity and local value creation

Fraunhofer ISE conducted a site analysis to determine which locations in Chile are particularly suitable for renewable electricity generation and for establishing large-scale production of green hydrogen derivatives. According to the analysis, the Antofagasta region in the north of the country shows great potential, as it already produces such high surpluses of solar power (from photovoltaics and concentrated solar thermal energy) that its grid feed-in must be curtailed. “In addition to more efficient use of electricity and local value creation, the project also contributes to the region’s development through German technology via the transfer of know-how,” explains Robert Szolak, Head of the Sustainable Synthesis Products Department.

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