Efficiency Estimates for Electromicrobial Production of Branched-chain Hydrocarbons

Electromicrobial production is a process where microorganisms use electricity as a charge and energy source for the production of complex molecules, often from starting compounds as simple as CO 2 . The aviation industry is in need for sustainable fuel alternatives that can meet their requirements of high-altitude performance while also meeting 21 st century carbon emissions standards. The electromicrobial production of jet fuel components with CO 2 -derived carbon provides a unique opportunity to generate jet fuel blends that are compatible with modern engines with net-neutral carbon emissions. In this study, we analyze the pathways necessary to generate single- and multi-branched-chain hydrocarbons in vivo utilizing both extracellular electron uptake (EEU) and H 2 -oxidation as methods for electron delivery, the Calvin cycle for CO 2 -fixation and the ADO decarboxylation pathway. We find the maximum electrical-to-fuel energy conversion efficiencies for single- and multi-branched chain hydrocarbons are and . Utilizing this information, as well as previously collected predictions on straight-chain alkane and terpenoid biosynthesis, we calculate the efficiency of electromicrobial production of jet fuel blends containing straight-chain, branched-chain, and terpenoid components. Increasing the fraction of branched-chain alkanes in the blend from zero to 47% only lowers the electrical energy conversion efficiency from to .