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 × 10³ 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. © 2020 The Authors. Biofuels, Bioproducts, and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd

中文翻译：

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与甘蔗生物精炼厂整合的异养微藻生物柴油生产的技术经济评估

在农作物和运输业务中使用柴油是甘蔗生物精炼厂碳排放量的三分之一。一种可能的解决方案是用高脂异养微藻直接从甘蔗生产的脂质类生物柴油代替它。在这项研究中，设计并评估了异养微生物微藻生物柴油厂，该厂与典型的巴西甘蔗生物精炼厂整合在一起。来自甘蔗加工的糖蜜，蒸汽和电被用作微藻生产的投入。对于非一体化工厂，微藻生物柴油的补料分批生产成本和连续工艺生产成本分别估计为2.51美元/升和2.27美元/升。种植和碳源设备是影响拟议设计财务可行性的最高成本。对于综合工厂，以目前乙醇和生物柴油的价格计算，其盈利能力将低于使用化石柴油作为运营原料的第一代甘蔗生物炼油厂。但是，CO₂排放量 每年最多可减少50,000×10 ³ kg，成本为83 10 ⁻³  kg ^-1 CO ₂当量。如果考虑碳信用额，则该过程即使在当前的燃油价格下也可以在经济上获利。©2020作者。化学工业协会和John Wiley＆Sons，Ltd出版的生物燃料，生物产品和生物精制