Comparative techno-economic and carbon footprint analysis of 2,3-butanediol production through aerobic and anaerobic bioconversion of carbon dioxide with green hydrogen
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Lueckel, Fabio Bozzolo
Scott, Felipe
Aroca, Germán
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<p>Renewable CO<sub>2</sub> and hydrogen have the potential to be the feedstocks of a decarbonized chemical industry, and biochemical conversions offer new alternatives for the industry. There are two options among chemolithotrophic bacteria capable of CO<sub>2</sub> fixation: under aerobic conditions, through the use of the Calvin-Benson-Basham cycle, known to produce large-chain compounds, and under anaerobic conditions, through the Wood-Ljungdahl pathway, known to produce short-chain organic molecules. Here, we report a comparison of both bioconversions, made at a simulated industrial scale, considering techno-economic and environmental variables, and using renewable CO<sub>2</sub> and H<sub>2</sub> as feedstocks. 2,3-butanediol, a mid-range chain compound that can be produced via both routes, was selected for comparison. The comparison was set up in Chile due to expected low-cost renewable hydrogen and renewable CO<sub>2</sub> availability. The assessment showed that the minimum selling price of 2,3-butanediol in the anaerobic case was higher (3.91 (USD kg<sup>−1</sup>)) than in the aerobic case (3.36 (USD kg<sup>−1</sup>)), with hydrogen being the largest expense in both processes (50 % and 70 % of total expenses respectively). Further, owing to metabolic restrictions, the anaerobic process required almost five times more CO<sub>2</sub> than the aerobic process to produce the same amount of 2,3-butanediol. A Monte Carlo analysis showed that in most scenarios the aerobic process was more economically favorable. In environmental terms, the aerobic process had a smaller carbon footprint in all the evaluated scenarios. Therefore, the results suggest that the aerobic process is a more suitable alternative to anaerobic bacteria-based processes for producing 2,3-butanediol from renewable CO<sub>2</sub> and hydrogen.</p>
Keywords
2,3-butanediol, Acetogenic, Carbon dioxide fixation, Hydrogen, Knallgas, LCA, SDG 7 - Affordable and Clean Energy