From CO2 to Economic Value: Modeling the Integration of CO2 Removal, Electrolysis, and Power Systems - Thesis

[Geoengineering News]

https://www.proquest.com/openview/e0f4eddad5ca6f2b8fd3e70d7be297e1/1?pq-origsite=gscholar&cbl=18750&diss=y

Authors: Hussain Almajed

2025

Abstract 

The role of CO2 capture, regeneration, and conversion in climate change mitigation is pivotal, serving not only to reduce and remove emissions but also to ensure carbon neutrality within future energy and chemical systems. Atmospheric CO2 capture coupled with CO2 conversion technologies represents a promising integration that could create value from CO2. However, the high costs associated with atmospheric CO2 capture and the low energy efficiency of the overall integrated system restrict its wide use in industry. Therefore, innovative research in this field is necessary to establish economically and environmentally feasible business models for wide

deployment. Low-temperature CO2 electrolysis represents an attractive process for upgrading CO2 to higher-value products using electricity. However, its low energy efficiency compared to thermochemical CO2 conversion methods presents a significant challenge that must be overcome before it could reach industrial deployment. While prior research in integrated CO2 capture and

electrolysis has focused on unit optimization, further research is still necessary to understand the optimal conditions for the full integrated system. Therefore, there is an immediate need for process and techno-economic models that bridge atmospheric CO2 capture with electrochemical CO2 conversion methods. This dissertation seeks to establish this bridge by utilizing process systems

engineering tools to accelerate process development and integration in this growing field. To accomplish this objective, several process models were developed to validly simulate the performance of CO2 capture units and electrochemical reactors. These models enabled the assessment of several air-to-X pathways, providing theoretical and practical insights into technoeconomic modeling that reduce the overall uncertainties in final conclusions. First, two air-to-syngas pathways were assessed to identify their main cost drivers and compare their potential economic values. The results from this study guided subsequent work that focused on a direct integration of alkaline direct air capture (DAC) with a neutral, liquid-based CO2 electrolyzer, in which we underscore the mismatch in pH levels for the capture and utilization steps. This pH

difference motivated mass and energy balance calculations around the integrated system, which elucidated practical trade-offs that may be overcome by pH swing steps. Both the presented and prior techno-economic analyses indicated that electricity pricing is a main cost driver in most of

the proposed scenarios. The combination of the aforementioned insights have led to a study of bipolar membrane electrodialysis (BPMED)—an electrochemical pH swing process—for CO2 regeneration and extraction purposes. Hourly wholesale electricity prices and grid CO2 emissions

were integrated with BPMED to assess its hourly operation and overall CO2 capture costs under different power supply scenarios. Findings underscore the importance of power system integration

with electricity-driven CO2 capture and conversion systems, driving future research to understand the trade-offs and synergies of this integration as we pursue decarbonization and defossilization. The modeling framework developed in this dissertation can be adopted to evaluate integrated CDR and electrochemical CO2 conversion systems, thereby contributing to the advancement of atmospheric CO2 capture and conversion technologies as well as the pursuit of global net zero goals.

Source: ProQuest