Direct air capture (DAC) technology, a critical tool in the fight against climate change, is gaining traction as a means to remove carbon dioxide directly from the atmosphere. This technology, which captures CO2 from ambient air, is increasingly seen as a key player in achieving carbon neutrality. Janusz Kotowicz, from the Department of Power Engineering and Turbomachinery at the Silesian University of Technology, has published a comprehensive review in the journal ‘Energies’ that delves into the advancements, challenges, and future prospects of DAC technologies.
The review highlights the potential of DAC to significantly reduce carbon emissions, especially in sectors where electrification is challenging, such as aviation, maritime transport, and heavy industry. Companies like Microsoft, Amazon, Aramco, and Siemens are already investing in DAC, recognizing its importance in meeting their net-zero carbon emission goals.
However, the widespread implementation of DAC faces significant hurdles, primarily high energy demands and substantial capture costs. Kotowicz emphasizes that the energy intensity of DAC processes is a major barrier. “The relatively low concentration of CO2 in atmospheric air, compared to industrial exhaust gases, makes the capture process energy-intensive,” Kotowicz explains. “Both solid and liquid sorbents require considerable energy for regeneration, which is a significant challenge.”
The review identifies two main approaches to DAC: liquid sorbents (L-DAC) and solid sorbents (S-DAC). L-DAC systems, which use solutions like sodium hydroxide or potassium hydroxide, are currently the most mature technology. However, they require high-temperature heat for regeneration, typically generated through natural gas combustion. In contrast, S-DAC systems use solid sorbents that can be regenerated with lower-temperature heat, making them more compatible with renewable energy sources.
Despite these challenges, there is optimism in the field. Alternative technologies, such as electrochemical and membrane-based processes, show promise. Electrochemical processes, for instance, could offer a more efficient and cost-effective solution, but they are still in the early stages of development. “Electrochemical processes are particularly sensitive to the presence of oxygen, and membrane-based DAC is limited by the current separation capabilities of available membranes,” Kotowicz notes.
The economic feasibility of DAC remains uncertain, with current estimates varying widely. Governmental and regulatory support will be crucial for the technology’s success. The review underscores the need for continued research to develop cost-effective and efficient sorbents, as well as more reliable economic analyses. “A significant problem is the considerable discrepancy between academic estimates and those declared by startups,” Kotowicz points out. “Therefore, the need for more detailed and reliable economic analyses is emphasized, which will better assess the potential of DAC technology in the long term.”
The location of DAC installations is another critical factor. Energy availability, options for CO2 storage or utilization, and climatic conditions all play significant roles in the efficiency of the capture process. Kotowicz’s review suggests that a comprehensive location assessment is essential before constructing any DAC installation.
This research by Kotowicz and his colleagues at the Silesian University of Technology provides a roadmap for the future of DAC technology. By addressing the challenges and identifying key research directions, the review offers a pathway to more efficient and cost-effective implementation of DAC. As the energy sector continues to evolve, DAC could play a pivotal role in achieving carbon neutrality, shaping the future of energy and environmental sustainability.
