Direct air capture (DAC) is a process with which carbon dioxide (CO₂) can be extracted directly from the ambient air. The Centre for Solar Energy and Hydrogen Research Baden-Württemberg (Zentrum für Sonnenenergie- und Wasserstoff-Forschung – ZSW) has been busily pressing ahead with the industrial roll-out of DAC technologies over the past two years in the “Direct Air Capture made in Baden-Württemberg (DAC-BW)” project, which is funded by the Baden-Württemberg Ministry of Transport. Enterprises in Baden-Württemberg have been directly consulted on the development so as to be able to deliver added value for the federal state. In its capacity as a research partner, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt – DLR) is seeking to optimise the design of the system with flow simulations. In the direct air capture process, the ambient air flows through an absorber which extracts some of the carbon dioxide. The CO2 obtained after desorption and concentration has a high degree of purity and can then be used as a raw material for the chemical industry for such purposes as the synthesis of basic chemicals like methanol or for refineries for the production of carbon-neutral fuels. Looking at air travel and international maritime shipping in particular, there are no commercially available alternatives to the use of carbon-based energy sources now or in the foreseeable future, which is why they must be urged to become CO2-neutral in order to meet the international climate control commitments.
Given the background context of industrial change in Baden-Württemberg – especially in the automotive sector – one focus of this project was to offer companies in the mechanical and plant engineering sector and in the supply industry advice and information on new business segments. The future markets for CO2 as a raw material were analysed and discussed in several workshops alongside in-depth exchange of technological perspectives in a wider discourse in industry. Initial estimates deduce that 100 million tons of CO2 will have to be removed from the atmosphere worldwide every year by as early as 2030 using direct air capture systems. The figure will rise to 1 to 2 gigatons of CO2 per year by 2050. This will serve as a basis for identifying the potential for added value and job creation in Baden-Württemberg. The project met with great interest in industry and the network has since grown to over 40 enterprises.
The foundation for the development of DAC technologies from Baden-Württemberg has therefore been laid. There is now a need to develop competitive DAC products and to boost production capacity for the market ramp-up going forward.
This will necessitate yet another decrease in the costs for DAC, however, and an increase in the size and scale of the technologies. Showing how this can be achieved, the ZSW demonstrated the latest prototype in operation in the third round of talks at industry level. The scrubber technology uses mainstream components and can harness waste heat – from downstream synthesis processes, for example – to cover a large proportion of the energy required. It is highly cost-efficient, boasting an electrical energy requirement of around one kilowatt hour of electric power per kilogramme of CO2. It has also proven its reliability and robustness in endurance tests in a demonstration facility with a separation capacity of around 10 tons of CO2 per year over more than 16,000 hours.
The newly commissioned plant was funded by the Baden-Württemberg Ministry of Economic Affairs and has a production capacity 10 times larger at 100 tons of CO2 per year. The technology is modular in design, allowing the system to be transported even to remote locations and assembled there to form larger plants with separation capacities in the range of tens of thousands or 100,000 tons of CO2 per year. “Having put this new facility into operation, the ZSW is now running one of the largest plants of its kind in Germany. It is the ideal basis for us to work with the companies on the further industrial roll-out and scaling of DAC,” said Dr. Marc-Simon Löffler who heads up the department of Renewable Fuels and Processes at the ZSW.
DAC plants up to the megaton scale, i.e. with separation capacities of more than one million tons of CO2 per year, will be required in the future if we want to push forward to relevant dimensions in the production of synthetic fuels or chemical raw materials. As things stand today, the goal must be to reduce the production costs of climate-neutral CO2 to well below 100 euro per ton under favourable site conditions (the CO2 price in the European emissions trading system is currently around 70 euro per ton of CO2). In order to achieve this, the cost of investing in such plants would have to be reduced considerably, with capital expenditure dropping to well under 500 euro per ton of annual production capacity. The ZSW is accompanying the enterprises on the onward journey, offering support by way of expert advice and test facilities.