Sustainability metrics of 1-butanol

• Comparison of petrochemical and biobased processes for 1-butanol.
• The petrochemical process is the oxo synthesis, i.e., the hydroformylation of propene.
• The biobased process is the acetone–butanol–ethanol fermentation.
• Four metrics are used: energy efficiency, material efficiency, land use and costs.
• The petrochemical process is more efficient than the biobased process.

The production of chemicals from renewable resources often has to compete with a petrochemical process, optimized during several decades. Four sustainability metrics were used to compare the production of 1-butanol via the petrochemical and biobased processes: material efficiency, energy efficiency, land use and total costs. The selected petrochemical process is the oxo synthesis, i.e., the hydroformylation of propene, followed by the hydrogenation of the formed aldehydes with a yield of 95% 1-butanol. The selected biobased process is the anaerobic continuous acetone–butanol–ethanol (ABE) fermentation on glucose substrate from maize starch and a product recovery via distillation with a yield of 0.42 g ABE g−1 glucose. The petrochemical process has significantly higher material and energy efficiencies, compared to the biobased process. For the biobased process, land is used to produce the biomass (0.29 ha ton−1), while no land is used for the petrochemical process. Production costs are higher for the biobased process (1041 EUR ton−1), compared to the petrochemical process (915 EUR ton−1). Based on the four metrics, the petrochemical process is preferable to the biobased process. However, biomass for sustainable fuels and chemicals will be the only resource for future generations. The efficiency of the biobutanol production can be improved by altering upstream processes, by metabolic engineering, by decreasing byproduct formation and by improving in situ product recovery techniques.

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