The goal of this research was to quantify the energy demand, carbon footprint, and financial cost of microalgae biomass processing with solar drying to produce biomass powder and anaerobic digestion, which is preceded by heat treatment, to produce biogas and biosolids. Microalgae biomasses were produced from cultivation in open raceway ponds in nutrient regimes with the availability and limitation of nitrogen and phosphorus. The methods used in this study were life cycle assessment (LCA) and techno-economic analysis (TEA). The largest contribution in the Processing stage was from the microalgae biomass production, which accounted for 43–91 % of the indicator values in the base scenarios. The production of bioproducts from microalgae cultivation in scenarios of nutrient limitation, higher biomass productivity, electricity supply from a photovoltaic plant, and nutrient supply from on-site residual sources combined reduced up to 61 % in energy demand, 79 % in carbon footprint, and 47 % in financial cost compared to those of the base scenarios. Biomass powder is a competitive input for substituting fossil-based materials in plastic composites. Even though the biomass composition change from microalgae cultivation in nutrient limitation, methane loss reduction, and multiproduct coproduction favored the viability of anaerobic digestion in the assessed categories, the financial cost of biogas production must be reduced to increase its competitiveness compared to fossil fuels. Therefore, the proposed strategies in the evaluated scenarios should be combined to increase the eco-efficiency in an integrated microalgae biorefinery.

中文翻译：

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微藻加工产生的生物质粉末、沼气和生物固体：技术、环境和经济绩效


本研究的目标是量化微藻生物质加工的能源需求、碳足迹和财务成本，通过太阳能干燥生产生物质粉末，并在热处理之前进行厌氧消化，以生产沼气和生物固体。微藻生物量是通过在开放式水道池塘中在氮和磷的可用性和限制的营养状况下培养而产生的。本研究使用的方法是生命周期评估（LCA）和技术经济分析（TEA）。加工阶段的最大贡献来自微藻生物量生产，占基础情景指标值的 43-91%。在养分限制、较高的生物质生产率、光伏发电厂的电力供应和现场剩余来源的养分供应的情况下，通过微藻培养生产生物产品，能源需求减少了 61%，碳足迹减少了 79%，并且与基本情景相比，财务成本降低 47%。生物质粉末是塑料复合材料中替代化石材料的有竞争力的原料。尽管微藻种植在营养限制、甲烷损失减少和多产品联产方面的生物质成分变化有利于评估类别中厌氧消化的可行性，但必须降低沼气生产的财务成本，以提高其与化石燃料相比的竞争力。因此，应结合评估情景中提出的策略来提高综合微藻生物精炼厂的生态效率。