Direct Air Capture (DAC) is a process for capturing carbon dioxide (CO₂) directly from the ambient air. Unlike conventional flue gas treatment, it does not require a point source such as a power station or factory — a DAC plant can be located wherever low-cost energy is available or there is a buyer for the CO₂.
This makes it possible to pursue two goals: first, CO₂ is permanently removed from the atmosphere if it is subsequently stored underground. Second, it produces a climate-neutral carbon feedstock that can replace fossil sources — for example, in the production of synthetic fuels (eFuels) for aviation and shipping, or as a raw material for the chemical industry.
The process produces highly concentrated, high-purity CO₂ with a purity of over 99.5 vol.%. At this quality, it can be used directly in downstream processes without further treatment.
What CO₂ can be used for
The utilisation of the CO₂ captured is not part of the current project – however, the potential applications are varied:
Synthetic fuels (e-fuels)
Feedstocks for the chemical industry
Permanent storage in underground reservoirs
Which option gains traction in the market first depends largely on the cost and purity of the capture process.
The procedure
01
Fans draw in ambient air and direct it into the absorber.
02
In the absorber, air rises while the scrubbing liquid trickles down from above. A packing structure distributes it into a thin film and increases the contact area. The liquid chemically binds the CO₂, while nitrogen and oxygen pass through unchanged.
03
The CO₂-rich liquid is pumped into the desorber and heated. The bond is broken, releasing CO₂ as a concentrated gas. The key is the low temperature required: heat that many plants already generate as part of their operations is sufficient—from synthesis, a furnace process or a biogas plant.
The DAC pilot plant
PlasmaAir AG has developed and built a pilot plant for capturing CO₂ from ambient air in collaboration with ZSW (Centre for Solar Energy and Hydrogen Research Baden-Württemberg).
The plant serves as a technology demonstrator and supplies around 10 kg/h of highly concentrated CO₂. It is installed at ZSW in Stuttgart-Vaihingen, where it is operated as a test facility for process qualification.
A key objective is to obtain reliable data on the process’s costs, purity and energy requirements, as these determine which applications can be implemented economically.