Hippel, Ted von (2018): Thermal removal of carbon dioxide from the atmosphere. Energy requirements and scaling issues. In Climatic Change 55 (D12), p. 1763. DOI: 10.1007/s10584-018-2208-0.

"I conduct a system-level study of direct air capture of CO₂ using techniques from thermal physics. This system relies on a combination of an efficient heat exchanger, radiative cooling, and refrigeration, all at industrial scale and operated in environments at low ambient temperatures. While technological developments will be required for such a system to operate efficiently, those developments rest on a long history of refrigeration expertise and technology, and they can be developed and tested at modest scale. I estimate that the energy required to remove CO₂ via this approach is comparable to direct air capture by other techniques. The most challenging aspect of building a system that could remove 1 billion tonnes of CO₂ from the atmosphere per year is the power demand of 112 to 420 GW during the wintertime operational period."

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