Optimizing direct air capture under varying weather conditions†

CO₂ from adsorption with supported-amine sorbents using steam-assisted temperature-vacuum swing adsorption is a technology to capture CO₂ from the atmosphere (direct air capture). This process has many operational parameters and, on top of that, is heavily influenced by the ambient temperature and relative humidity. Identifying the minimum cost of direct air capture becomes a multi-dimensional problem in which climate conditions has to be incorporated as well. This study aims to evaluate the cost of direct air capture for year-round operation and to relate this to climate conditions. An optimization framework was developed with the ambient conditions as input parameters. This framework is able to find the minimum cost of direct air capture for a given fixed bed DAC facility and provides the corresponding operational parameters. These results were coupled to year-round weather data to find the total costs for continuous operation. We showed that the cost of CO₂ capture from air correlates well with the average annual temperature, with a high average temperature being more beneficial. Furthermore, climates with strong variation in weather conditions over the seasons require dynamic process control in order to operate at minimum cost of DAC. Overall, the presented optimization framework is an excellent tool to identify suitable locations for direct air capture and provide the operational parameters to minimize its cost.