System boundary setting in life cycle assessment of biorefineries: a review

详细信息    查看全文

• 作者：A. Bernstad Saraiva
• 关键词：Allocation ; Biorefinery ; End ; of ; life ; Feedstock ; Life cycle assessment ; System boundary
• 刊名：International Journal of Environmental Science and Technology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：14
• 期：2
• 页码：435-452
• 全文大小：
• 刊物主题：Environment, general; Environmental Science and Engineering; Environmental Chemistry; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution; Soil Science & Conservati
• 出版者：Springer Berlin Heidelberg
• ISSN：1735-2630
• 卷排序：14

文摘

A growing interest for biorefineries has resulted in a subsequent increase in publication of lifecycle assessments (LCA) of such systems in later years. This study explores choices made in system boundary setting in LCAs of biorefinery systems. Based on a review of 38 case studies published in the scientific literature, the study aims to identify and discuss methodological differences and effects of these on overall results. The review shows that the definition of feedstock is of key importance for chosen system boundary settings. Direct inputs and agriculture activities are included in 80 % of the systems where feedstock is regarded as dedicated biomass, while omitted when defined as residue. Land conversion for provision of dedicated biomass, as well as use of agriculture/forest residues, results in impacts with direct connection to the investigated biorefinery system, motivating inclusion of these processes in the assessment. However, these aspects are considered in less than 40 and 30 % of systems using dedicated biomass and residues as feedstock, respectively. Indirect land use changes and ‘lost opportunities’ can be relevant to assess—independent of the type of feedstock used, particularly when using consequential modeling. Such indirect aspects are, however, not always addressed in a coherent manner. Finally, it is observed that the end-of-life stage of bio-materials/chemicals commonly is not captured within set system boundaries, generating comparative disadvantage for bio-based systems, when compared to fossil reference systems. In summary, it can be concluded that omitting key issues from the investigated system can reduce the relevance of gained results, as well as the possibilities for cross-study comparisons. This calls for further development and use of already existing guidelines in this field.