Issue 22, 2021

Is electrochemical CO2 reduction the future technology for power-to-chemicals? An environmental comparison with H2-based pathways

Abstract

Power-to-chemical pathways are gaining attention as a promising approach to reduce greenhouse gas (GHG) emissions of the chemical industry. Most power-to-chemical pathways use water electrolysis and hydrogenation of carbon dioxide (H2-based pathways). An emerging power-to-chemical technology is electrochemical CO2 reduction (eCO2R) that converts carbon dioxide (CO2) and water (H2O) directly into chemical products. An early assessment of the environmental potential of eCO2R can accelerate the eCO2R development toward more sustainable technology. So far, only a few environmental assessments have been conducted using fixed assumptions of eCO2R operating parameters. To overcome this limitation and reflect all possibilities of future eCO2R development, we design a parameter-dependent approach using a variable eCO2R model. The considered eCO2R model can produce carbon monoxide (CO), methanol, or ethylene. Together with the conversion of syngas (CO and hydrogen mixture) to methanol and with the methanol-to-olefins (MtO) conversion to ethylene, five different eCO2R pathways to produce methanol and ethylene are possible. By applying our parameter-dependent approach, we determine the minimum development requirements for the eCO2R pathways to achieve climate benefits over the H2-based pathways. By comparing the obtained minimum development requirements to data from experimental studies, we evaluate potential development gaps. The direct eCO2R to ethylene pathway shows a moderate development gap and could reduce GHG emissions over the H2-based pathway by up to 44%. The eCO2R via CO to methanol and eCO2R via CO to ethylene pathways can already fulfill the minimum development requirements; however, the GHG reduction potential is limited to 12%. The direct eCO2R to methanol pathway shows a significant development gap. Compared to the fossil fuel-based technologies, both the H2-based and the eCO2R pathways offer large climate benefits of up to 88% and up to 93%, respectively. The presented parameter-dependent assessment offers an in-depth understanding of the eCO2R operating parameters and provides a valuable approach for future assessments of the emerging eCO2R technology.

Graphical abstract: Is electrochemical CO2 reduction the future technology for power-to-chemicals? An environmental comparison with H2-based pathways

Supplementary files

Article information

Article type
Paper
Submitted
28 Jun 2021
Accepted
10 Sep 2021
First published
14 Oct 2021
This article is Open Access
Creative Commons BY-NC license

Sustainable Energy Fuels, 2021,5, 5748-5761

Is electrochemical CO2 reduction the future technology for power-to-chemicals? An environmental comparison with H2-based pathways

J. Wyndorps, H. Ostovari and N. von der Assen, Sustainable Energy Fuels, 2021, 5, 5748 DOI: 10.1039/D1SE00975C

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