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PURPOSE: The framework of life cycle sustainability analysis (LCSA) has been developed within the CALCAS project but the procedure on how an LCSA should be carried out is still far from standardized. The purpose of this article is to propose an approach to put the LCSA framework into practice. This approach is illustrated with an on-going case study on concrete recycling. METHODS: In the context of an EC-FP7 project on technology innovation for concrete recycling, five operational steps to implement the LCSA framework are proposed: (1) broad system definition, (2) making scenarios, (3) defining sub-questions for individual tools, (4) application of the tools and (5) interpreting the results in an LCSA framework. Focus has been put on the goal and scope definition (steps 1–3) to illustrate how to define a doable and meaningful LCSA. Steps 4–5 are not complete in the case study and are elaborated theoretically in this paper. RESULTS AND DISCUSSION: The experience from the case study shows that the operational steps are especially useful at the stage of defining the goal and scope. Breaking down the sustainability questions into different scales and different aspects gives the possibility to define the sub-questions suitable to be assessed by the individual analytical tools (e.g., LCA, LCC, SLCA, MFA, etc.). The C2CA-LCSA shows a practical approach to model the life cycle impacts of the broad system is to start by modelling the technological system at the micro level and then scale it up with the realistic scenario settings that are generated with the knowledge gained from the MFA studies at the meso-level and from the policy/economic studies at the macro level. The combined application of LCA, LCC and SLCA at the project level shows not all the cost items and only one social impact indicator can be modelled in the process-based LCA structure. Thus it is important to address the left out information at the interpretation step. CONCLUSIONS: Defining sub-questions on three different levels seems most useful to frame an LCSA study at the early stage of goal and scope definition. Although this study provides some useful steps for the operationlisation of the LCSA concept, it is clear that additional case studies are needed to move LCSA into a practical framework for the analysis of complex sustainability problems.

The ongoing energy transition from fossil fuels to renewables is increasing the demand for materials, particularly metals. As fossil fuel infrastructure, such as refineries, tankers, pipelines, and ships, is phased out, this obsolete infrastructure could serve as an urban mine, supplying secondary materials like steel, aluminium, and copper. However, the extent to which these materials can meet future needs remains unclear and is often overlooked. Here we develop the global dynamic fossil fuel material model to quantify material stocks embedded in fossil fuel infrastructure and project secondary material availability through 2050 under the Shared Socioeconomic Pathway 2 (SSP2) baseline and 2-degree Celsius (2D) scenarios. Our findings indicate that material demand for new infrastructure continues to grow under the baseline scenario and exceeds recoverable volumes. Even under the 2D scenario, the surplus of recovered metals remains insufficient to meet the growing material requirements of renewable energy technologies. Material demand for renewable energy technology under the medium emissions and two-degree Celsius scenarios exceeds the amount recovered from decommissioned fossil fuel infrastructure, according to an analysis that uses a dynamic fossil fuel material model.

Purpose As capture fishery production has reached its limits and global demand for aquatic products is still increasing, aquaculture has become the world’s fastest growing animal production sector. In attempts to evaluate the environmental consequences of this rapid expansion, life cycle assessment (LCA) has become a frequently used method. The present review of current peer-reviewed literature focusing on LCA of aquaculture systems is intended to clarify the methodological choices made, identify possible data gaps, and provide recommendations for future development within this field of research. The results of this review will also serve as a start-up activity of the EU FP7 SEAT (Sustaining Ethical Aquaculture Trade) project, which aims to perform several LCA studies on aquaculture systems in Asia over the next few years. Methods From a full analysis of methodology in LCA, six phases were identified to differ the most amongst ten peer-reviewed articles and two PhD theses (functional unit, system boundaries, data and data quality, allocation, impact assessment methods, interpretation methods). Each phase is discussed with regards to differences amongst the studies, current LCA literature followed by recommendations where appropriate. The conclusions and recommendations section reflects on aquaculture-specific scenarios as well as on some more general issues in LCA. Results Aquaculture LCAs often require large system boundaries, including fisheries, agriculture, and livestock production systems from around the globe. The reviewed studies offered limited coverage of production in developing countries, low-intensity farming practices, and non-finfish species, although most farmed aquatic products originate from a wide range of farming practices in Asia. Apart from different choices of functional unit, system boundaries and impact assessment methods, the studies also differed in their choice of allocation factors and data sourcing. Interpretation of results also differed amongst the studies, and a number of methodological choices were identified influencing the outcomes. Conclusions and recommendations Efforts should be made to increase transparency to allow the results to be reproduced, and to construct aquaculture related database(s). More extensive data reporting, including environmental flows, within the greater field of LCA could be achieved, without compromising the focus of studies, by providing supporting information to articles and/or reporting only ID numbers from background databases. More research is needed into aquaculture in Asia based on the latest progress made by the LCA community.

Normalization is an optional step in LCIA that is used to better understand the relative importance and magnitude of the impact category indicator results. It is used for error checking, as a first step in weighting, and for standalone presentation of results. A normalized score for a certain impact category is obtained by determining the ratio of the category indicator result of the product and that of a reference system, such as the world in a certain year or the population of a specific area in a certain year. In determining these two quantities, the numerator, the denominator, or both can suffer from incompleteness due to a lack of emission data and/or characterisation factors. This leads to what we call a biased normalization. As a consequence. the normalized category indicator result can be too low or too high. Some examples from hypothetical and real case studies demonstrate this. Especially when for some impact categories the normalized category indicator result is right, for others too low, and for others too high, severe problems in using normalized scores can show up. It is shown how this may affect the three types of usage of normalized results: error checking, weighting and standalone presentation. Some easy checks are proposed that at least alert the LCA practitioner of the possibility of a biased result. These checks are illustrated for an example system on hydrogen production. A number of remedies of this problem is possible. These are discussed. In particular, casedependent normalization is shown to solve some problems, but on the expense of creating other problems. It appears that there is only one good solution: databases and tables of characterisation factors must be made more completely, so that the risk of detrimental bias is reduced. On the other hand, the use of the previously introduced checks should become a standard element in LCA practice, and should be facilitated with LCA software.[PUBLICATION ABSTRACT]

To strengthen the evaluative power of LCA, life cycle interpretation should be further developed. A previous contribution (Heijungs & Kleijn 2001) elaborated five examples of concrete methods within the subset of numerical approaches towards interpretation. These methods were: contribution analysis, perturbation analysis, uncertainty analysis, comparative analysis, and discernibility analysis. Developments in software have enabled the possibility to apply the five example methods to explore the much-used Ecoinvent\"96 database. The numerical approaches implemented in this study include contribution analysis, perturbation analysis, uncertainty analysis, comparative analysis, discernibility analysis and the newly developed key issue analysis. The data used comes from a very large process database: Ecoinvent'96, containing 1163 processes, 1181 economic flows and 571 environmental flows. Results are twofold: they serve as a benchmark to the usefulness and feasibility of these numerical approaches, and they shed light on the question of stability and structure in an often-used large system of interconnected processes. Most of the approaches perform quite well: computation time on a moderate PC is between a few seconds a few minutes. Only Monte Carlo analyses may require much longer, but even then it appears that most questions can be answered within a few hours. Moreover, analytical expressions for error propagation are much faster than Monte Carlo analyses, while giving almost identical results. Despite the fact that many processes are connected to each other, leading to the possibility of a very unstable system and very sensitive coefficients, the overall results show that most results are not extremely uncertain. There are, however, some exceptions to this positive message.[PUBLICATION ABSTRACT]

-DOI: http://dx.doi.org/10.1065/lca2006.04.008Goal, Scope and Background CML has contributed to the development of life cycle decision support tools, particularly Substance / Material Flow Analysis (SFA respectively MFA) and Life Cycle Assessment (LCA). Ever since these tools emerged there have been discussions on how these tools relate to each other, and how they relate to more traditional tools. Remarkably little, however, has been published on these relationships from an empirical side: which combinations of tools have actually been used, and what is the added value of combining tools in practical case studies. In this paper, we report on CML's experience in this field by presenting a number of case studies with their related research questions, for which different tools were deployed. Methods Three case studies are discussed: 1) Waste water treatment: various options for waste water treatment have been assessed on their eco-efficiency, using SFA to comment on the influence of these options on the flows of certain substances in the water system of a geographical area and a combination of LCA and life cycle costing (LCC) to assess the life-cycle impacts and costs of these options; 2) Prioritization of environmental policy measures: A methodology has been developed to prioritize environmental policy measures and investments within companies based on both the environmental impacts and the costs of these measures; and 3) Environmental weighting of materials: to add an environmental dimension to standard MFA accounts, materials were weighted with cradle-to-grave impact factors based on LCA data and impact assessment factors. Results and Discussion For each of these cases, the research questions at stake, the tools applied, the results and the added value, limitations and problems of combining the tools are reported. Conclusionsand Perspective. Based on these experiences, it is concluded that using several tools to address a complicated problem is not only a theoretical proposal, but also something that has been applied successfully in a variety of practical situations. Furthermore, using several tools in combination does not necessarily lead to an increased information supply to decisionmakers. Instead, it may contribute to the comprehensibility and ease of interpretation of the information that would have been provided by using a single tool. Finally, it is concluded that there is not one generally valid protocol for which tools to use for which question. The essential idea of using a combination of tools is exactly the fact that research questions are not simple by nature and cannot be generalized into protocols.

The ISO-standard for LCA distinguishes four phases, of which the last one, the interpretation, is the least elaborated. It can be regarded as containing procedural steps (like a completeness check) as well as numerical steps (like a sensitivity check). This paper provides five examples of techniques that can be used for the numerical steps. These are the contribution analysis, the perturbation analysis, the uncertainty analysis, the comparative analysis, and the discernibility analysis. All five techniques are described at a non-technical level with respect to basic concept, possibilities, tabular and graphical representation, restriction and warnings, and all are illustrated with a simple example.

The European Union is faced with major environmental problems related to nitrogen (N) compounds. The origins of three such problems, the atmospheric deposition of N compounds, the leaching of nitrates to ground-water and the anthropogenic N-input to the North Sea, are investigated by means of a Substance Flow Analysis (SFA); the reference year is 1988. Although the problems occur at various scales and have varying direct causes, food production and consumption together are the main responsible sectors, and the production and import of fertilizer appear to be the major ultimate sources in all three cases. Measures to combat these problems have been agreed to in various international frameworks: the European Community, the International North Sea Conference and the Rhine States Conference. These measures include technical emission reduction for acidifying compounds resulting in a 30% emission reduction; extension of the sewage treatment network and application of denitrification with 50% effectiveness; and introduction of measures directed at efficiency increase and emission reduction in agricultural practice in 10% of the agricultural area. The recent changes in the Common Agricultural Policy (CAP) are not expected to lead to significant changes in N flows. Assuming full implementation, an almost sufficient 45% reduction is expected for the anthropogenic nitrogen input into the North Sea. The atmospheric deposition of nitrogen compounds will be reduced by approximately 20%. The leaching of nitrates to the ground-water is expected to remain at the current level or even to increase a little. In all, these measures are conducive to solving, but do not satisfactorily solve, the three problems, mainly because the ultimate origins of the problems are not sufficiently influenced and measures therefore inevitably result in a shifting of problems.