Proceedings of the 1st International Symposium on African Sustainable Energy Solutions (AfrSusEnS 2024)

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Theoretical Energy Requirements and Practical Challenges of CO2 Separation from Air for Methanol Production

Authors
Diane Hildebrandt1, *, Joshua Gorimbo2, Yali Yao2
1Chemical & Biochemical Engineering, Rutgers, The State University of New Jersey, 98, Brett Road, Piscataway, NJ, 08854-8058, USA
2Institute for Catalysis and Energy, Solution (ICES), College of Science, Engineering and Technology, University of South Africa (UNISA), Florida, Johannesburg, 1710, South Africa
*Corresponding author. Email: diane.hildebrandt@rutgers.edu
Corresponding Author
Diane Hildebrandt
Available Online 22 July 2025.
DOI
10.2991/978-94-6463-797-7_7How to use a DOI?
Keywords
Direct Air Capture (DAC); CO2 Separation; Methanol Synthesis; Thermodynamic Efficiency; Energy Consumption; Carbon Utilization
Abstract

The separation of carbon dioxide (CO2) from the atmosphere using direct air capture (DAC) technology is a key step toward sustainable methanol production. The minimum theoretical work (MTW) required for CO2 separation is set by thermodynamics, however the actual energy consumption is significantly higher due to process inefficiencies, such as handling large air volumes. This paper presents a thermodynamic analysis of the MTW for CO2 separation and compares it to the MTW required for the chemical transformation of CO2 and water into methanol.

The analysis reveals that although the MTW for CO2 separation is substantial—168 kWh per ton of methanol—it is still 30 times lower than the MTW required for methanol synthesis, which stands at 6,095 kWh per ton. Furthermore, the very large air flow rates needed for DAC, at a minimum of 1.75 million m3 of air (STP) per ton of methanol, pose significant operational challenges and potential inefficiencies. However, the economic feasibility of the overall process will be primarily determined by the methanol synthesis stage, given its high energy demands.

Copyright
© 2025 The Author(s)
Open Access
Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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Volume Title
Proceedings of the 1st International Symposium on African Sustainable Energy Solutions (AfrSusEnS 2024)
Series
Advances in Engineering Research
Publication Date
22 July 2025
ISBN
978-94-6463-797-7
ISSN
2352-5401
DOI
10.2991/978-94-6463-797-7_7How to use a DOI?
Copyright
© 2025 The Author(s)
Open Access
Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

Cite this article

risenwbib
TY  - CONF
AU  - Diane Hildebrandt
AU  - Joshua Gorimbo
AU  - Yali Yao
PY  - 2025
DA  - 2025/07/22
TI  - Theoretical Energy Requirements and Practical Challenges of CO₂ Separation from Air for Methanol Production
BT  - Proceedings of the 1st International Symposium on African Sustainable Energy Solutions (AfrSusEnS 2024)
PB  - Atlantis Press
SP  - 44
EP  - 49
SN  - 2352-5401
UR  - https://doi.org/10.2991/978-94-6463-797-7_7
DO  - 10.2991/978-94-6463-797-7_7
ID  - Hildebrandt2025
ER  -