(401b) Design and Operation of Direct Air Capture (DAC) Systems Under Varying Environmental Conditions

To address climate change caused by rising levels of carbon dioxide (CO₂) in the atmosphere, direct air capture (DAC) as a negative emission technology, has become an active area of research [1][2]. Several DAC sorbent-loaded fibers systems have been developed using different adsorbent materials. Adsorption on solid amine sorbent-loaded fibers is a promising alternative because of low manufacturing cost, low pressure drop, and use of low temperature steam for regeneration [3][4].

The objective of this work is to model, simulate, and optimize DAC systems utilizing silica-supported polyethylenimine adsorbents embedded in porous polymer fibers under varying ambient conditions. Literature studies have frequently assumed that the DAC process is run under constant lab conditions. However, the ambient temperature and humidity of many locations vary both seasonally and with the time of day, which can lead to different optimal operating conditions at different timescales [5]. In our approach the design is performed by optimizing the operation of a cycle over a limited number of scenarios where the design variable is the system size to capture a fixed quantity of CO₂. The scenarios are generated from statistical distributions of ambient temperature and humidity for a given location. To adjust the performance of the system to reflect the predicted temperature and humidity trends over several hours, dynamic optimization of operation is performed for several cycles using a rolling-horizon approach with surrogate models built from more detailed dynamic models used to perform optimization of the future cycles.

References:

1. McQueen, K. Vaz Gomes, C. McCormick, K. Blumanthal, M. Pisciotta, and J. Wilcox, "A review of direct air capture (DAC): scaling up commercial technologies and innovating for the future," in Prog. Energy, vol. 3, no. 3, Art. no. 032001, Apr. 2021, doi: 10.1088/2516-1083/abf1ce.
2. Pacala, M. Al-Kaisi, M. Barteau, et al., "Negative Emissions Technologies and Reliable Sequestration: A Research Agenda," in *Proc. Natl. Acad. Sci. U.S.A.*, 2019, doi: 10.17226/25259.
3. Rim, F. Kong, M. Song, C. Rosu, P. Priyadarshini, R. P. Lively and C. W. Jones, "Sub-ambient temperature direct air capture of CO2 using amine-impregnated MIL-101(CR) enables ambient temperature co2 recovery," JACS Au, vol. 2, no. 2, pp. 380-393, 2022.
4. Kalyanaraman, Y. Fan, R. P. Lively, W. J. Koros, C. W. Jones, M. J. Realff and Y. Kawajiri, "Modeling and experimental validation of carbon dioxide sorption on hollow fibers loaded with silica-supported poly(ethylenimine)," Chemical Engineering Journal, vol. 259, pp. 737-751, 2015.
5. F. Wiegner, A. Grimm, L. Weimann, and M. Gazzani, "Optimal Design and Operation of Solid Sorbent Direct Air Capture Processes at Varying Ambient Conditions," Ind. Eng. Chem. Res., vol. 61, no. 34, pp. 12649–12667, Aug. 2022, doi: 10.1021/acs.iecr.2c00681.