(560b) Integrated Technology for Cost-Effective CO2 Capture and Formic Acid Production: Modeling, Optimization, and Economic Analysis

Due to the significant costs associated with conventional carbon capture and storage (CCS) technologies, there is a growing emphasis on exploring alternative approaches to mitigate CO₂ emissions. Converting CO₂ into chemicals and energy products shows promise in not only reducing emissions but also creating economic value due to high market potential. Revenue generated from utilizing CO₂ can also offset a portion of the CO₂ capture cost. Integrating CO₂ capture and conversion can eliminate the need for costly CO₂ transport and storage in conventional CCS applications, reducing costs by up to $45 per ton [1].

The National Energy and Technology Laboratory (NETL) has been exploring alternative carbon capture and utilization methods that offer high efficiency and competitive costs. A novel reactive technology is being investigated that electrochemically converts CO₂ into valuable chemicals, particularly formic acid. This work focuses on identifying the optimal design and operation of an integrated membrane-based CO₂ capture unit with the electrochemical conversion process. In this setup, the CO₂ in the flue gas permeates through a CO₂-selective membrane and enters an electrolyzer to produce formic acid, creating an integrated reaction module. To refine the chemical product, gas products from the electrolyzer are directed to a pressure swing adsorption unit, while the liquid product undergoes refinement to achieve commercial-grade formic acid using reactive distillation.

A membrane CO₂ capture model and an electrochemical conversion model have been developed using the IDAES Integrated Platform (Institute for the Design of Advanced Energy System) [2], facilitating rigorous flowsheet modeling and process design and optimization. The membrane model demonstrates good performance in CO₂ capture across a variety of conditions, ranging from 4% to 12% CO₂ concentration in volume. A rigorous electrochemical conversion model based on first principles has also been developed, with partial differential equations discretized in two dimensions to describe the heat, mass, and charge transfers along multiple layers of the electrolyzer cell, as well as the kinetics of catalytic electrochemical reactions on both cathode and anode sides. In this work, the integrated analysis shows the optimal process design and operation and provides valuable insights into competitive low- and no-carbon formic acid production routes.

[1] Smith E, Morris J, Kheshgi H, Teletzke G, Herzog H, Paltsev S. The cost of CO2 transport and storage in global integrated assessment modeling. International Journal of Greenhouse Gas Control. 2021 Jul 1;109:103367.

[2] Lee A, Ghouse JH, Eslick JC, Laird CD, Siirola JD, Zamarripa MA, Gunter D, Shinn JH, Dowling AW, Bhattacharyya D, Biegler LT. The IDAES process modeling framework and model library—Flexibility for process simulation and optimization. Journal of advanced manufacturing and processing. 2021 Jul;3(3):e10095.

Disclaimer:

This project was funded by the Department of Energy, National Energy Technology Laboratory an agency of the United States Government, through a support contract. Neither the United States Government nor any agency thereof, nor any of its employees, nor the support contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof, or any of their contractors.