A geographic analysis and techno-economic assessment of renewable heat sources for low-temperature direct air capture in Europe

Integrated assessment model (IAM) scenarios examining pathways to achieve the goals of the Paris Agreement stress the necessity of deploying carbon dioxide removal (CDR) methods, of which direct air capture (DAC) is viewed as one of the most promising. This study undertakes both a geospatial analysis and techno-economic assessment of potential heat sources for DAC to examine the economic impact of different renewable heat source systems on the capture costs of large-scale LT-DAC plants. It does this by determining the location of these plants through the paradigm of identifying the ideal geographic and economic environment for the selected heat sources. Thus, the research aims to answer the following research questions: What heat sources are optimally suited for low-temperature (LT) DAC and what conditions are feasible for setup? Which geographic locations represent the ideal environment within Europe for each heat source? How do the selected heat sources and geographic locations impact the economic viability of LT-DAC? Drawing on Climeworks’ LT-DAC approach as a focal case, the heat sources of geothermal energy, parabolic trough collector (PTC), industrial waste heat (IWH), and high-temperature heat pump (HTHP) were chosen, to be separately deployed in Iceland, Spain, Germany, and Norway, respectively. Spain emerged as a highly promising location for the PTC, IWH, and HTHP systems while Iceland is most suitable for the geothermal, IWH, and HTHP systems. Norway is a promising country mostly for deploying a HTHP system, whereas Germany faces primarily environmental and legal barriers. The techno-economic assessment identified great variation in the LCOD costs for the different heat source systems, with the geothermal energy system exhibiting the lowest costs at 175.63 €/tCO₂ followed by the IWH, PTC, and HTHP systems. Future LCOD costs could potentially see a significant reduction of up to 66 % depending on the heat source system based on projected decreases in DAC CAPEX costs. A cost comparison revealed that current carbon price levels within the European Emission trading scheme are not expected to be sufficiently high enough to drive large investments in the development and scaling of LT-DAC. Cost levels of CCS technologies and LT-DAC could however be comparable, in particular for the geothermal energy system.