From enzyme to cell-factory: Economic and environmental assessment of biobased pathways to unlock the potential of long-haul transportation biofuels

Abstract

The transportation sector significantly contributes to greenhouse gas emissions due to its reliance on fossil fuels. Biofuels offer a low-carbon alternative, particularly for long-haul transportation. Although few biosynthetic pathways reached technological maturity with commercial plants, recent literature shows a variety of laboratory-scale progresses targeting these biofuels. Early-stage sustainability assessments can help identify opportunities for metabolic engineering and process improvements toward more sustainable routes. This study evaluated the technical, economic, and environmental aspects of producing drop-in biofuels from sugarcane and soybean oil, considering fermentative and enzymatic processes. The results showed that sugarcane-based scenarios presented a better prospect and that integrating steps within microorganisms’ metabolism in a cell factory concept had advantages over the cell-free enzymatic process. Biobased pathways, however, still require improvements to be competitive with catalytic-based alternatives. Recommendations were made to guide microorganism engineering, focusing on factors that restrain economic and environmental feasibility (e.g., inputs use). As a result, the improved biobased process could provide a hydrocarbon-based fuel with a minimum selling price (US$ 21.2 GJ−1) compatible with market prices and carbon intensity (25.1 gCO2eq MJ−1) similar to that from sugarcane ethanol, representing over 70 % reduction in greenhouse gas (GHG) emissions compared to fossil fuels.