Using carbon dioxide (CO2) as a raw material and thus avoiding CO2 emissions is a key concept behind the “ALIGN-CCUS” pilot project, which came to an end in November 2020, and the successor project “TAKE-OFF”, which began in January 2021. Whereas in ALIGN-CCUS, the goal of RWE Power, Mitsubishi Power Europe and Asahi Kasei was the production of dimethyl ether (DME) from captured CO2, electricity and water, TAKE-OFF goes a step further. It aims to provide an efficient means of producing aviation fuel from DME in an additional process stage. The research plant for DME manufacture at the RWE Innovation Centre in Niederaussem produced DME for the first time at the time of commissioning in June 2020.
TAKE-OFF involves developing the production of synthetic renewable aviation fuel from CO2 and H2. Two process routes that were investigated use DME for this purpose, and methanol produced in Niederaussem will also be used in the future.
The new process
The new process makes it possible to synthesise DME in a single process stage in the synthesis plant designed and installed by Mitsubishi Power Europe with a monolithic reactor and a newly developed catalyst. To date, methanol has been produced from CO2 and hydrogen, with DME only in a second stage. The starting point for DME synthesis is CO2, which is obtained from the flue gas at the Niederaussem lignite power station using amine scrubbing. The plant is designed for a total capacity of about 7.2 tonnes of CO2 per day. Every day up to 180 kg of CO2 and 22 kg of hydrogen are converted into DME. The hydrogen used to synthesise DME is generated on-site using highly efficient alkaline electrolysis from Asahi Kasei. The new synthesis plant thus produces up to 50 kg of raw RME per day. The CO2 not used for CCUS projects at the Niederaussem Innovation Centre is made available to the Jülich Research Centre for plant research.
DME and methanol are energy sources that can be both stored and transported. Thanks to their high power density, they can be used as long-term chemical energy storage systems and also as synthetic fuels, if no lower-carbon alternative is available. In addition, DME and methanol are also chemical raw materials for many other applications, such as primary stages for compounds used in cosmetics, washing agents, dyes or medications, or even as intermediate products in the production of aviation fuels.
Even after fossil-fuelled power stations are decommissioned, there will still be unavoidable sources of CO2 from a range of industrial processes. ALIGN-CCUS and TAKE-OFF illustrate a technology that can use CO2 as a raw material and thus replace fossil-based raw materials in conjunction with hydrogen. Basic chemicals or fuels based on DME and methanol, which are produced in this way from captured CO2 and, with an eye to the future, green hydrogen, enable energy to be stored and transported in chemical form, and thus function as a link between sectors and contribute towards a successful energy transition.
