To this aim and to achieve this threshold, it has been estimated that over 10 gigatons of greenhouse gases, primarily carbon dioxide, must be captured annually from the air by 2050 [2]. Inside this context, negative emission technologies are essential alongside point source capture systems because they offer a means to actively remove carbon dioxide from the atmosphere, helping to compensate emissions that are difficult to eliminate entirely.
Among negative emission technologies, Direct Air Capture (DAC) play crucial roles, complementing approaches such as afforestation and reforestation, Bioenergy with Carbon Capture and Storage (BECCS), and Ocean Alkalinity Enhancement (OAE), mineral carbonation, etc. [3]. Different DAC systems have been investigated and proposed and some companies have already built a large-scale plant [4]. However, in the last years, in addition to thermally driven DAC processes, DAC systems moved totally by electrical energy have been received the attention of the research community [5]. In particular, the Bi-Polar Membrane Electro-Dialysis (BPME) cell can be coupled to an absorption column capturing carbon dioxide from the air with the aim to release the captured carbon dioxide inside carbonates and regenerate the hydroxide solvent for the column [6].
However, the BPMED system has some challenges due to the generated carbon dioxide gas bubbles that can have negative effects on membranes and cause higher energy consumptions [7]. For this reason, a new solution is proposed in this work: it is suggested that carbonates from the absorption column react with a weak acid (e.g. formic acid or acetic acid/formic acid mixture) producing a salt acid that can be sent to a BPMED cell able to regenerate both the acid and hydroxide solvent of the absorption column. On the other hand, carbon dioxide is released during the reaction between carbonates and acids avoiding the formation of bubbles inside the electrochemical cell.
The considered processes (e.g. the BPMED for carbon dioxide release and BPMED for acid regeneration both coupled with an absorption column capturing carbon dioxide from the air) have been modelled in Aspen Plus software so that energy consumptions and total costs are evaluated for a comparison purpose.
References
[1] A.D.a.A. Ghosh, Summary of Global Climate Action at COP 28 United Nations Framework Convention on Climate Change, United Arab Emirates 2023, p. 2
[2] A. Lieber, M. Hildebrandt, S.-L. Davidson, J. Rivero, H. Usman, T.H.R. Niepa, K. Hornbostel, Demonstration of direct ocean carbon capture using encapsulated solvents, Chem. Eng. J. 470 (2023) 144140
[3] C. Le Quere, R.J. Andres, T. Boden, T. Conway, R.A. Houghton, J.I. House, G. Marland, G.P. Peters, G.R. Van Der Werf, A. Ahlstrom, ¨ R.M. Andrew, L. Bopp, J.G. Canadell, P. Ciais, S.C. Doney, C. Enright, P. Friedlingstein, C. Huntingford, A.K. Jain, C. Jourdain, E. Kato, R.F. Keeling, K. Klein Goldewijk, S. Levis, P. Levy, M. Lomas, B. Poulter, M.R. Raupach, J. Schwinger, S. Sitch, B.D. Stocker, N. Viovy, S. Zaehle, N. Zeng, The global carbon budget 1959–2011, Earth System Science Data 5(1) (2013) 165-185
[4] G. Leonzio, P.S. Fennell, N. Shah, Analysis of Technologies for Carbon Dioxide Capture from the Air. Applied Sciences, (2022), 12(16), 8321
[5] H. Bouaboula, J. Chaouki, J. Belmabkhout, A. Zaabout, Comparative review of Direct air capture technologies: From technical, commercial, economic, and environmental aspects, Chemical Engineering Journal 484 (2024) 149411
[6] F. Sabatino, M. Gazzani, F. Gallucci, M. van Sint Annaland, Modeling, Optimization, and Techno-Economic Analysis of Bipolar Membrane Electrodialysis for Direct Air Capture Processes, Ind. Eng. Chem. Res. (2022), 61, 12668−12679
[7] S.V. Castano, Q. Shu, M. Shi, R. Blauw, P.L. Fosbøl, P. Kuntke, M. Tedesco, H.V.M. Hamelers, Optimizing alkaline solvent regeneration through bipolar membrane electrodialysis for carbon capture, Chemical Engineering Journal 488 (2024) 150870