The consortium analyzed the entire value chain: from production from hydrogen and CO2 from the air (Direct Air Capture, DAC) through the intermediates methanol and dimethyl ether (DME) to diesel and gasoline fractions as well as Sustainable Aviation Fuels (SAF). DME played a central role in this. The gas is non-toxic, has a high energy density, and is suitable as an energy carrier and as a raw material for the chemical industry.
Four scenarios were considered for the years 2030 to 2040 with the export countries Finland, Spain, and Brazil. Four technologies from the Federal State of Baden-Württemberg were evaluated: DAC, hydrogen or synthesis gas production via the bioliq process of the Karlsruhe Institute of Technology (KIT), DME production via the Indigo process of Fraunhofer ISE, and the production of SAF and other fuel fractions. Methanol served as a comparison reference as the current state of the art.
Indigo process with lower costs than methanol route
In a process simulation, the researchers compared two DME synthesis processes – Indigo and a conventional process – with methanol synthesis. According to Fraunhofer ISE, the Indigo process showed significantly lower operating and total costs. The project partner Mineraloelraffinerie Oberrhein has the option to implement the process as a licensee in its refinery.
KIT investigated for the first time in the laboratory the individual processes for olefin and fuel synthesis from DME in continuous operation. According to the institute, energy efficiency increases to up to 90 percent compared to the methanol route, correspondingly reducing CO2 emissions. From the oligomerization products, the researchers produced gasoline and diesel fractions as well as SAF.
Test stand for Direct Air Capture developed with Purem
In parallel, Purem GmbH and Fraunhofer ISE investigated a DAC process based on solid sorbents. The newly developed test stand was operated in cyclic mode with industrially relevant air streams. "The developed scaling concept enables cost-effective production of DAC modules in automated manufacturing environments of the automotive industry. Further experimental studies on a pilot scale are required for investment decisions," explains Robert Szolak, Head of Sustainable Synthesis Products at Fraunhofer ISE.
The techno-economic analyses showed that the fuel production costs in the innovation scenario with technology from Baden-Württemberg are lower in all scenarios than those of the reference scenario with methanol. "Our study has shown that the transformation to sustainable fuels based on DME offers significant potential for cost reduction. Baden-Württemberg, with its industrial base and strong mechanical and plant engineering, has ideal conditions for the market ramp-up of e-fuels. To realize these potentials, proactive entrepreneurial action and supportive industrial and technology policy are necessary," says Achim Schaadt, also Head of Sustainable Synthesis Products at Fraunhofer ISE.
