Potential of Repurposed Cooling Towers for Direct Air Capture in Germany

[Geoengineering News]

https://www.tugraz.at/fileadmin/user_upload/Events/Eninnov/EnInnov2026/files/lf/165_LF_Sager.pdf

Authors: Robert Sager, Nils Hendrik Petersen, Manfred Wirsum

Abstract 

To successfully mitigate climate change, the use of renewable energy sources in all sectors is required. In addition, negative emission technologies (NETs) will play a crucial role to reduce the atmospheric CO2 concentration, offset emissions from hard-to-abate sectors, and provide CO2 as a feedstock for a circular carbon economy. Among NETs, the direct separation of CO2 from ambient air (Direct Air Capture, DAC) is considered as a particularly scalable option. However, DAC faces major challenges in terms of high energy demands and high investment cost as large air mass flows must be processed given the low CO2 concentration in ambient air (~ 400 ppm). Cooling towers of thermal power plants (eg, coalfired power plants) process air mass flows comparable to those anticipated for large-scale DAC units (ie, 1 MtCO2/a capture capacity). Consequently, as countries phase out coal-fired power plants, an opportunity arises to repurpose existing cooling towers as DAC units. Within the research project ConTACtFuels, funded by the German Ministry of Digital and Transport, the potential of repurposing components of thermal power plants for DAC has been investigated.

In this paper, the techno-economic potential of repurposing power plant infrastructure in DAC with subsequent storage or fuel synthesis is investigated for Germany. The Levelized Cost of Direct Air Capture (LCODAC) is used as main metric to illustrate trade-offs between reduction in investment cost and increasing operational cost due to the repurposed infrastructure. Overall, the repurpose of cooling towers from coal-fired power plants with a capacity> 150 MWel in Germany results in an annual capture capacity of up to 2.3 MtCO2/a at an average LCODAC of 174.39€/tCO2. To prove the validity of the results in real world application and enable a rollout, preliminary lab-and field tests as well as in-depth discussions of process integration, civil engineering, social, and ecological research questions must be carried out.

Source: Tugraz