The economic implications of reactor design and scale-up for aerobic production of biofuels

Aeration plays an essential role in large-scale biological sugars-to-hydrocarbon production. The current understanding of aeration scalability and economics for very large-scale applications such as are envisioned for commodity biofuels is limited. High oxygen transfer rates may be required to enable high productivity hydrocarbon production from biomass-derived sugars.  Air compressors and powerful motors are needed to supply the quantity of air and agitation necessary to maintain adequate rates of oxygen transfer in submerged cultures. Aeration of submerged cultures is therefore costly to implement and requires engineering optimization. This study explores aerobic bioreactor design options appropriate for large-scale biofuels production. It also provides an initial assessment of the economic tradeoffs between achievable oxygen transfer rate, bioreactor unit size, and estimated minimum fuel selling price. Results highlight that significant knowledge gaps remain regarding optimal bioreactor design, aeration methods, and operating conditions in the context of producing low-cost, large-scale commodity biofuels.