Techno-economic assessment of heterotrophic microalgae biodiesel production integrated with a sugarcane bio-refinery

The use of diesel fuel in crop and transportation operations is responsible for one third of the carbon emissions in sugarcane biorefineries. A possible solution is to replace it with biodiesel from lipids, directly produced from sugarcane by highly productive heterotrophic microalgae. In this study a heterotrophic microalgae biodiesel plant, integrated with a typical Brazilian sugarcane bio-refinery, was designed and evaluated. Molasses, steam, and electricity from sugarcane processing were used as inputs for microalgae production. For a non-integrated plant, the production cost of the microalgae biodiesel was estimated at 2.51 and 2.27 $/liter for fed-batch and continuous processes, respectively. Equipment for cultivation and carbon sources was the highest cost affecting the financial feasibility of the proposed design. For the integrated plant, at present ethanol and biodiesel selling prices, the profitability would be lower than a first-generation sugarcane bio-refinery using fossil diesel fuel for its operations. However, the CO2 emissions would be reduced by up to 50 000 x 10(3) kg per year at a cost of $83 10(-3) kg(-1) CO2-eq. If carbon credits are considered, the process becomes economically profitable even at present fuel prices. (c) 2020 The Authors. Biofuels, Bioproducts, and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd

Automated summary

The study explores the potential of using biodiesel from highly productive heterotrophic microalgae as a sustainable alternative to diesel fuel in sugarcane biorefineries. While the production cost is relatively high due to equipment and carbon sources, the process can become economically profitable with the consideration of carbon credits. The integration of microalgae biodiesel production with sugarcane processing can significantly reduce carbon emissions, making it a viable solution for reducing environmental impact.