Environmentally-Extended Input-Output Analysis

Dear Colleagues,

Challenging problems arise in the assessment of the environmental burdens associated with certain products or processes. In this context, two main approaches are currently used which are either too complex or too aggregated to deliver a valuable framework assessment. Conventional life cycle assessment (LCA), henceforth denoted as P-LCA, is a bottom-up approach that considers material and energy flows for each component across a product’s life cycle, eventually leading to results that can be obtained at a higher level of detail and accuracy. The other approach, also known as environmentally extended input–output (EEIO) analysis, is a top-down technique that provides an analysis that accounts for transactions throughout the entire economy in which inventories are quantified using monetary data at the level of distinct economic activity sectors.

In general, two major concerns arise with the use of P-LCA methods: establishing the boundary limits of the analysis, and circularity effects. The definition of the boundary has implications on the time and burden imposed when collecting the data required, and if not carefully considered it may limit the results, leading to an underestimation of the actual life cycle impacts. On the other hand, the circulatory effects can only be included by completing an LCA of all materials and processes before completing an LCA of any material or process. Therefore, many assumptions and decisions are required in order to conduct a comprehensive LCA, thus making it a very complex and time-consuming endeavor. Moreover, P-LCA studies are usually conducted by means of proprietary software and data, meaning that assumptions and boundary choices are not transparent to those who view the results.

EEIO is a methodological framework sought to simplify LCA which is based on an input–output (IO) matrix with the economic flows between industries that can be extended with information regarding the environmental discharges to the environment, creating additional columns and rows that represent the environmental impacts of each activity sector/industry. The EEIO framework eliminates the two major issues raised by P-LCA, since the transactions and emissions of all activity sectors/industries are embedded in the analysis, and its boundary becomes very broad and inclusive. Further, since the self-sector flows are also considered, the circularity effects are also included.

Nevertheless, although the EEIO approach does not involve the same problem of truncation as P-LCA, this methodological approach inherently involves higher sectoral aggregation, and thus sector resolution might become rather unclear. Therefore, the use of the EEIO approach in the framework of products or processes not specifically accounted for in IO tables is challenging. Consequently, when official published IO data do not provide a clear identification of products and processes, additional approaches are required to this end.

In this context, it is frequently helpful to develop hybrid methodologies, combining the broad stance of EEIO with the specificity of information for a single product or process of a P-LCA.

Therefore, contributions are expected to cover a wide range of topics, including: the application of the EEIO approach in the assessment of the environmental implications of specific products or processes; updated reviews of EEIO studies applied to specific products or processes with a discussion of the major challenges and the suggestion of possible ways to overcome the problems involved. Contributions reporting the combination of the EEIO approach with other mathematical programming tools to real-world case studies are also particularly appreciated.

All papers will undertake a rigorous review process according to the quality standards of Sustainability. Papers must comprise original research, and numerical illustrations should refer to realistic case studies for which data should be given (in the paper or as supplementary material) to guarantee the replicability of results. Papers should contribute novel and noteworthy research relative to the relevant literature.

Prof. Dr. Carla Oliveira Henriques
Guest Editor

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• input–output analysis
• environmental impact assessment
• energy impact assessment
• economic/social impact assessment
• economy–energy–environment (E3) models
• multi-objective optimization