Closing the Loop: Unexamined Performance Trade-Offs of Integrating Direct Air Capture with (Bi)carbonate Electrolysis

Hussain Almajed, Recep Kas, Paige Brimley, Allison Crow, Ana Somoza-Tornos, Bri-Mathias Hodge, Thomas Burdyny, Wilson Smith

Research output: Contribution to journalArticlepeer-review


CO2 from carbonate-based capture solutions requires a substantial energy input. Replacing this step with (bi)carbonate electrolysis has been commonly proposed as an efficient alternative that coproduces CO/syngas. Here, we assess the feasibility of directly integrating air contactors with (bi)carbonate electrolyzers by leveraging process, multiphysics, microkinetic, and technoeconomic models. We show that the copresence of CO32- with HCO3-in the contactor effluent greatly diminishes the electrolyzer performance and eventually results in a reduced CO2 capture fraction to <=1%. Additionally, we estimate suitable effluents for (bi)carbonate electrolysis to require 5-14 times larger contactors than conventionally needed contactors, leading to unfavorable process economics. Notably, we show that the regeneration of the capture solvent inside (bi)carbonate electrolyzers is insufficient for CO2 recapture. Thus, we suggest process modifications that would allow this route to be operationally feasible. Overall, this work sheds light on the practical operation of integrated direct air capture with (bi)carbonate electrolysis.
Original languageAmerican English
Pages (from-to)2472-2483
Number of pages12
JournalACS Energy Letters
Issue number5
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5900-89806


  • atmospheric chemistry
  • electrocatalysts
  • electrolysis
  • ions
  • solvents


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