TY - JOUR
T1 - A system boundary identification method for life cycle assessment
AU - Li, Tao
AU - Zhang, Hongchao
AU - Liu, Zhichao
AU - Ke, Qingdi
AU - Alting, Leo
N1 - Funding Information:
Acknowledgments The authors would like to thank National Basic Research Program of China (973 Program: 2011CB013406) for supporting the investigations.
PY - 2014/3
Y1 - 2014/3
N2 - Purpose: Life cycle assessment (LCA) is a useful tool for quantifying the overall environmental impacts of a product, process, or service the scientific scope and boundary definition are important to ensure the accuracy of LCA results. Defining the boundary in LCA is difficult and there are no commonly accepted scientific methods yet the objective of this research is to present a comprehensive discussion of system boundaries in LCA and to develop an appropriate boundary delimitation method. Methods: A product system is partitioned into the primary system and interrelated subsystems the hierarchical relationship of flow and process is clarified by introducing flow- and process-related interventions. A system boundary curve model of the LCA is developed and the threshold rules for judging whether the system boundary satisfies the research requirement are proposed. Quantitative criteria from environmental, technical, geographical and temporal dimensions are presented to limit the boundaries of LCA. An algorithm is developed to identify an appropriate boundary by searching the process tree and evaluating the environmental impact contribution of each process while it is added into the studied system. Results and discussion: The difference between a limited system and a theoretically complete system is presented. A case study is conducted on a color TV set to demonstrate and validate the method of boundary identification the results showed that the overall environmental impact indicator exhibits a slow growth after a certain number of processes considered, and the gradient of the fitting curve trends to zero gradually. According to the threshold rules, a relatively accurate system boundary could be obtained. Conclusions: It is found from this research that the system boundary curve describes the growth of life cycle impact assessment (LCIA) results as processes are added the two threshold rules and identification methods presented can be used to identify system boundary of LCA the case study demonstrated that the methodology presented in this paper is an effective tool for the boundary identification.
AB - Purpose: Life cycle assessment (LCA) is a useful tool for quantifying the overall environmental impacts of a product, process, or service the scientific scope and boundary definition are important to ensure the accuracy of LCA results. Defining the boundary in LCA is difficult and there are no commonly accepted scientific methods yet the objective of this research is to present a comprehensive discussion of system boundaries in LCA and to develop an appropriate boundary delimitation method. Methods: A product system is partitioned into the primary system and interrelated subsystems the hierarchical relationship of flow and process is clarified by introducing flow- and process-related interventions. A system boundary curve model of the LCA is developed and the threshold rules for judging whether the system boundary satisfies the research requirement are proposed. Quantitative criteria from environmental, technical, geographical and temporal dimensions are presented to limit the boundaries of LCA. An algorithm is developed to identify an appropriate boundary by searching the process tree and evaluating the environmental impact contribution of each process while it is added into the studied system. Results and discussion: The difference between a limited system and a theoretically complete system is presented. A case study is conducted on a color TV set to demonstrate and validate the method of boundary identification the results showed that the overall environmental impact indicator exhibits a slow growth after a certain number of processes considered, and the gradient of the fitting curve trends to zero gradually. According to the threshold rules, a relatively accurate system boundary could be obtained. Conclusions: It is found from this research that the system boundary curve describes the growth of life cycle impact assessment (LCIA) results as processes are added the two threshold rules and identification methods presented can be used to identify system boundary of LCA the case study demonstrated that the methodology presented in this paper is an effective tool for the boundary identification.
KW - Life cycle assessment
KW - Process tree
KW - Search algorithm
KW - System boundary
KW - Threshold rule
UR - http://www.scopus.com/inward/record.url?scp=84898876625&partnerID=8YFLogxK
U2 - 10.1007/s11367-013-0654-5
DO - 10.1007/s11367-013-0654-5
M3 - Article
AN - SCOPUS:84898876625
VL - 19
SP - 646
EP - 660
JO - International Journal of Life Cycle Assessment
JF - International Journal of Life Cycle Assessment
SN - 0948-3349
IS - 3
ER -