Techno-economic assessment of single-cell protein production at industrial scale from a wide range of carbon sources

Abstract

Using aerobic fermentation, single-cell protein (SCP) can be produced from a wide range of carbon sources (C-sources), including glucose, glycerol, methanol, ethanol, and organic acids. The technical and economic performance of large-scale SCP production varies significantly with C-source, driven by differences in biomass yield, O2 demand, and productivity, for example. To determine the preferred C-source, a techno-economic assessment for continuous SCP production in an industrial bubble column was performed for nine non-gaseous C-sources. This was based on a process model that included microbial kinetics, gas-liquid mass transfer kinetics, downstream operations, and a detailed cost analysis. Per C-source, dilution rate and aeration conditions were optimized to minimize the minimum selling price (MSP) of SCP. The results highlight C-source costs as the dominant MSP driver, with O₂ transfer rates strongly affecting capital and utility costs. At their current prices, glucose, glycerol, methanol and ethanol emerge as the most economically favorable C-sources, achieving MSPs of about 2.5 $/kgₓ due to high biomass yields and low C-source prices. Acetic acid exhibits an MSP of 3.2 $/kgₓ but, lactic, formic, glycolic and oxalic acids exhibit MSPs in the range of 7–20 $/kgₓ due to low biomass yields, high O2 demand, and high C-source prices. Sensitivity analyses confirm that C-source price and biomass yield exert the strongest economic influence, while the electricity price and fixed costs have a more marginal effect. This work identifies promising candidates for further environmental and scale-up assessments, providing a framework to guide C-source selection and process optimization for SCP production.