© ZSW, Ellen Klose

ZSW succeeds in producing climate-neutral eLNG from air CO2

The sphere gleams silver in the middle of a high-tech installation consisting of many hoses, compressors, switches and buttons. It reminds a little of a fortune teller’s crystal ball. And the future is what this is all about. The plant, which was developed by the Centre for Solar Energy and Hydrogen Research Baden-Württemberg, is intended to achieve climate neutrality more quickly. The system demonstrator at the ZSW in Stuttgart generates synthetic liquid methane from hydrogen and air – so-called eLNG – using electricity from renewable energies. Unlike LNG (Liquified Natural Gas), which is based on fossil natural gas, synthetic electricity-based eLNG (electrified LNG) is produced in a climate-neutral way. This is because the liquid gas is produced from green hydrogen and carbon dioxide from the ambient air.

Research on the “eLNG from the air” project funded by the Baden-Württemberg Ministry of Economics began 1.5 years ago. Now the project has been successfully completed with the demonstration of the entire process chain. The technology can now be transferred to an industrial scale.

“The production of CO2-neutral gas is an important building block on the way to a climate-neutral future. With this project, we want to support our plant engineers and component manufacturers in Baden-Württemberg in using the technology to open up new export potential and sales markets,” said Minister of Economic Affairs Dr. Nicole Hoffmeister-Kraut.

Existing technology modules and infrastructures at the ZSW were used for the project. These include a technology for extracting CO2 from the air and an electrolysis process for producing green hydrogen. What was still missing was an innovative, combined method to efficiently produce and liquefy the regenerative methane gas. This process has now been developed at the ZSW.

Liquefied methane has an energy density 600 times higher than gaseous methane and thus allows, among other things, the intercontinental transport of large amounts of energy by ship. In this way, the already existing infrastructures for LNG can be transformed in the direction of climate neutrality. As a new, climate-neutral fuel, eLNG can be used instead of diesel for shipping and heavy goods transport or as a heating oil alternative in industry. The CO2 supply from air further developed in the project – as well as the scaling concepts of the overall process – can also be transferred to other fuel syntheses, for example for the production of synthetic kerosene.

When liquid methane flowed into the silver sphere for the first time in the ZSW pilot plant, the joy was great. “The amount of liquid methane was still small, but the proof of concept had been provided,” reports Dr. Marc-Simon Löffler, head of the ZSW’s Renewable Energy Sources and Processes department. He and his colleagues are particularly proud of the fact that all the components in the process chain – electrolysis, CO2 scrubber, methanation and liquefaction – were developed in-house. “The plant is 100 percent made by ZSW,” adds project manager Bernd Stürmer. After proving that the demonstrator works, the process steps were further optimized. In the meantime, the yield of the laboratory plant has been increased to one kilogram per hour.

The ZSW scientists have already developed scaling concepts with which the process can also be used on an industrial scale. With optimal process integration, an efficiency of up to 55 percent (based on the regenerative electricity used) is possible with this technology.

After this research success, things are moving forward. The next step is now to win partners from industry for the commercialization of the technology modules. To this end, the ZSW’s Systems Analysis department is investigating the value creation potential for industry in Baden-Württemberg. “The plant concept opens up opportunities for companies in various industries. In particular, the technology for extracting CO2 from air is not only an important component of the eLNG process chain, but also promises great development prospects in the global market for climate protection measures,” summarizes Maike Schmidt, Head of Systems Analysis at ZSW. The project also aims to identify new export potentials and sales markets for companies. This will create the conditions for Baden-Württemberg to take on a pioneering role as a technology provider for the production of electricity-based, regenerative liquid methane.