Life-cycle assessment of an industrial direct air capture process based on temperature–vacuum swing adsorption

• Published in: Nature energy 2021-02, Vol.6 (2), p.203-213
• Main Authors: Deutz, Sarah, Bardow, André
• Format: Article
• Language: English
• Subjects: 639/4077/4057; 704/844/4081; 704/844/682; Adsorbents; Air temperature; Amines; Carbon dioxide; Carbon dioxide emissions; Carbon sequestration; Clean energy; Climate; Construction planning; Economics and Management; Energy; Energy Policy; Energy sources; Energy Storage; Energy Systems; Environmental impact; Industrial plants; Life cycle analysis; Life cycle assessment; Plant construction; Renewable and Green Energy; Temperature requirements; Wind power
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-020-00771-9

Current climate targets require negative carbon dioxide (CO 2 ) emissions. Direct air capture is a promising negative emission technology, but energy and material demands lead to trade-offs with indirect emissions and other environmental impacts. Here, we show by life-cycle assessment that the commercial direct air capture plants in Hinwil and Hellisheiði operated by Climeworks can already achieve negative emissions today, with carbon capture efficiencies of 85.4% and 93.1%. The climate benefits of direct air capture, however, depend strongly on the energy source. When using low-carbon energy, as in Hellisheiði, adsorbent choice and plant construction become more important, inducing up to 45 and 15 gCO 2 e per kilogram CO 2 captured, respectively. Large-scale deployment of direct air capture for 1% of the global annual CO 2 emissions would not be limited by material and energy availability. However, the current small-scale production of amines for the adsorbent would need to be scaled up by more than an order of magnitude. Other environmental impacts would increase by less than 0.057% when using wind power and by up to 0.30% for the global electricity mix forecasted for 2050. Energy source and efficiency are essential for direct air capture to enable both negative emissions and low-carbon fuels. Direct air capture (DAC) of CO 2 has garnered interest as a negative emissions technology to help achieve climate targets, but indirect emissions and other environmental impacts must be better understood. Here, Deutz and Bardow perform a life-cycle assessment of DAC plants operated by Climeworks, based on industrial data.