Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark.
Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark.
Sci Total Environ. 2017 Nov 15;598:497-512. doi: 10.1016/j.scitotenv.2017.04.087. Epub 2017 Apr 25.
This study evaluates the environmental impacts of biorefinery products using consequential (CLCA) and attributional (ALCA) life cycle assessment (LCA) approaches. Within ALCA, economic allocation method was used to distribute impacts among the main products and the coproducts, whereas within the CLCA system expansion was adopted to avoid allocation. The study seeks to answer the questions (i) what is the environmental impacts of process integration?, and (ii) do CLCA and ALCA lead to different conclusions when applied to biorefinery?. Three biorefinery systems were evaluated and compared: a standalone system producing bioethanol from winter wheat-straw (system A), a standalone system producing biobased lactic acid from alfalfa (system B), and an integrated biorefinery system (system C) combining the two standalone systems and producing both bioethanol and lactic acid. The synergy of the integration was the exchange of useful energy necessary for biomass processing in the two standalone systems. The systems were compared against a common reference flow: "1MJ+1kg", which was set on the basis of products delivered by the system C. Function of the reference flow was to provide service of both fuel (bioethanol) at 99.9% concentration (wt. basis) and biochemical (biobased lactic acid) in food industries at 90% purity; both products delivered at biorefinery gate. The environmental impacts of interest were global warming potential (GWP), eutrophication potential (EP), non-renewable energy (NRE) use and the agricultural land occupation (ALO). Regardless of the LCA approach adopted, system C performed better in most of the impact categories than both standalone systems. The process wise contribution to the obtained environmental impacts also showed similar impact pattern in both approaches. The study also highlighted that the recirculation of intermediate materials, e.g. C sugar to boost bioethanol yield and that the use of residual streams in the energy conversion were beneficial for optimizing the system performance.
本研究采用基于影响的（CLCA）和基于分配的（ALCA）生命周期评估（LCA）方法评估生物炼制产品的环境影响。在 ALCA 中，经济分配方法用于将影响分配给主要产品和副产物，而在 CLCA 系统中，采用系统扩展来避免分配。本研究旨在回答以下问题：（i）过程集成的环境影响是什么？（ii）当应用于生物炼制时，CLCA 和 ALCA 是否会得出不同的结论？评估并比较了三个生物炼制系统：一个从冬小麦秸秆生产生物乙醇的独立系统（系统 A），一个从紫花苜蓿生产生物基乳酸的独立系统（系统 B），以及一个将两个独立系统结合起来生产生物乙醇和乳酸的集成生物炼制系统（系统 C）。整合的协同作用是两个独立系统中生物质加工所需的有用能量的交换。系统与一个共同的参考流进行了比较：“1MJ+1kg”，该参考流是基于系统 C 提供的产品设定的。参考流的功能是提供燃料（生物乙醇）的服务，浓度为 99.9%（wt. basis），以及生化（生物基乳酸）在食品工业中的服务，纯度为 90%；两种产品均在生物炼制厂门口交付。本研究关注的环境影响指标有全球变暖潜势（GWP）、富营养化潜势（EP）、不可再生能源（NRE）的使用和农业土地占用（ALO）。无论采用哪种 LCA 方法，系统 C 在大多数影响类别中的表现都优于两个独立系统。从过程角度来看，这两种方法的环境影响贡献模式也相似。本研究还强调了中间材料（如 C 糖）的再循环以提高生物乙醇产量，以及剩余流在能源转化中的利用对优化系统性能的益处。
