Accounting for the dissipation of abiotic resources in LCA: Status, key challenges and potential way forward.

The concept of resources or materials dissipation after their use in the technosphere has been increasingly considered in life-cycle based studies, applying Substance and Material Flow Analysis (SFA and MFA), Input-Output Analysis, and Life Cycle Assessment (LCA). However, there is currently no common understanding of what a dissipative flow is. This article first reviews 45 publications to describe the status of resource dissipation in life-cycle based studies, discussing how resource dissipation is usually defined, which temporal perspective is considered, which compartments of dissipation are distinguished, and which approaches (including the implementation of parameters) are considered to assess resource dissipation in a system. Moreover, this article proposes a comprehensive definition of resource dissipation, building from the literature review and focusing on abiotic resources. It then discusses this definition with respect to its potential implementation in LCA considering today's existing Life Cycle Inventory (LCI) datasets and best practices. Overall it shows that the LCA framework may be well suited to assess abiotic resource dissipation. In particular i) the compartments of dissipation usually considered in the literature are covered in LCA, and ii) LCI databases could be a source of information to be further used to quantify a set of flows defined as "dissipative", as commonly considered in SFA/MFA studies. However, major challenges are still faced before any potential routine implementation in LCA. The article accordingly discusses the potential way forward in the short-term (development and test of possible approaches), mid-term (towards satisfactory robustness, and consensus) and long-term (large-scale changes of LCI databases).

Environmental impacts of household consumption in Europe: Comparing process-based LCA and environmentally extended input-output analysis.

The environmental impacts generated by household consumption are generally calculated through footprints, allocating the supply-chain impacts to the final consumers. This study compares the result of the Consumer Footprint indicator, aimed at assessing the impacts of household consumption in Europe, calculated with the two standard approaches usually implemented for footprint calculations: (i) a bottom-up approach, based on process-Life cycle assessment of a set of products and services representing household consumption, and (ii) a top-down approach, based on environmentally extended input-output tables (EXIOBASE 3). Environmental impacts are calculated considering 14 environmental impact categories out of the 16 included in the EF2017 impact assessment method. Both footprints show similar total values regarding climate change, freshwater eutrophication and fossil resource use, but in the meantime very large differences (more than a factor 2) regarding particulate matter, photochemical ozone formation, land use and mineral resource use. The exclusion of services in the bottom-up approach can explain only to some extent these differences. However, the two approaches converge in identifying food as the main driver of impact in most of the impact categories considered (with a generally lower contribution in top-down compared to bottom-up). Housing and mobility are relevant as well for some impact categories (e.g. particulate matter and fossil resource depletion). Some substances are identified as hotspot by both approaches, e.g. the emission of NH3 to air (for acidification and terrestrial eutrophication), of NOx to air (for acidification, marine and terrestrial eutrophication, and, to some extent, photochemical ozone formation), of P to water and to soil (for freshwater eutrophication) and of fossil CO2 to air (for climate change). Significant differences at the inventory side are key drivers for the differences in total impacts. These include: (i) differences in the intensity of emissions, (ii) differences in the coverage of elementary flows, (iii) differences in the level of detail relative to elementary flows. Overall, the key converging results from both approaches (in particular regarding most contributing areas of consumption and substances) can be considered as a robust basis to support the definition of policies aimed at reducing the environmental footprint of household consumption in Europe.

Assessing the environmental impacts of EU consumption at macro-scale.

Sustainable Consumption and Production is one of the leading principle towards reducing environmental impacts globally. This study aims at combining Environmentally-Extended Input-Output Analysis (using EXIOBASE 3) with up-to-date impact assessment models to quantify the environmental impacts induced by final consumption in the EU Member States in 2011. The environmental extensions are characterized in 14 environmental impact categories out of the 16 used in the Environmental Footprint life cycle impact assessment method. A contribution analysis of key products and services as well as emissions and resources, which drive the environmental impacts of EU consumption, is conducted. Environmental impacts are mainly induced along the supply-chain of products and services. Several expenditures relative to services represent large shares both in the total final consumption and in the 14 impacts under study, despite a relatively low impact intensity. Food products, in particular meat and dairy products, are identified as key contributors regarding acidification, eutrophication, land use, and water use, and to a lower extent climate change. Finally, several manufactured products, raw materials and basic products respectively importantly contribute to impacts on human toxicity, freshwater ecotoxicity and resource uses. The total volume of final consumption expenditures per EU Member State appears a key explanatory variable to most of the impacts embodied in their consumption, yet to a lower extent regarding water use and fossils resource use. Finally, the current limitations in using EXIOBASE 3 for environmental impact assessment are discussed, with specific attention to EXIOBASE environmental extensions and to the case study on EU consumption. Since the classification of emissions and resources for impact assessment requires a number of assumptions that may influence the results, a sensitivity analysis is performed to exemplify some of the key issues relative to the characterization of impacts based on EXIOBASE environmental extensions.

Life cycle assessment of the French municipal solid waste incineration sector.

This study aims at assessing the environmental performances of the French MSW incineration sector in a life cycle perspective, considering nine midpoint impact categories. It is the first application of the WILCI tool, dedicated to the LCA of MSW incineration in the French situation (Beylot et al., 2017). The model is primarily based on operational data relative to 90 plants, representing 73% of the total mass of MSW annually incinerated in France. Regarding seven impact categories out of the nine under study, incineration of MSW in France provides a benefit (that is, a "negative" impact). The uncertainty analysis confirms the relatively large degree of confidence of this conclusion regarding acidification and particulate matter, but in the meantime highlights the remaining uncertainty regarding most other impact categories. Energy recovery is responsible for the main share of the total environmental impacts and benefits of MSW incineration in France. Moreover, this study confirms the importance of technology differentiation in the LCA of MSW incineration. The predominance, in the French incineration sector, of energy recovery as CHP, and of SCR for NOx abatement, results in the global environmental benefits calculated per tonne of average MSW incinerated. Finally, this study addresses the contribution of each waste fraction to the total impacts and benefits of MSW incineration. It identifies several fractions whose contributions to impacts and benefits are not in line with their share in the composition of MSW incinerated.

A consumption approach to wastes from economic activities.

In a context of waste management policies aimed at promoting waste prevention and recycling and, conversely, reducing waste landfilling, this study investigates how waste is generated and treated in a consumption perspective. A Waste Input-Output Analysis is implemented that considers 14 waste fractions and four waste management techniques. Input-Output Tables extended to wastes are initially compiled for the year 2008 considering France and five of its main import suppliers, and further completed with data on waste treatment. Wastes from economic activities are accordingly reallocated to the product categories of household consumption that induce their production. In particular, considering five waste categories (dry recyclable wastes, mixed wastes, mineral wastes, organic wastes, and total wastes) as an aggregation of the 14 waste fractions studied, the ten product categories with the highest contribution account for 64-86% of the total generation of wastes. Waste intensity and volume of expenses are analyzed as the drivers for the amounts of wastes induced by each product category. Similarly, the products responsible for the largest amounts of waste landfilling and incineration without energy recovery, i.e. the management techniques at the bottom of the "waste management hierarchy", are identified. Moreover, this study highlights the relative importance of waste produced abroad as compared to that produced in France, regarding the total amount of waste induced by French household consumption. The sensitivity of results to the modeling of import production is subsequently discussed. Finally, the potential perspectives for this type of consumption approach are considered with respect to its utility and current limitations in a context of waste policy planning, and more particularly regarding the way waste policy targets are set.

Life Cycle Assessment of mechanical biological pre-treatment of Municipal Solid Waste: a case study.

The environmental performance of mechanical biological pre-treatment (MBT) of Municipal Solid Waste is quantified using Life Cycle Assessment (LCA), considering one of the 57 French plants currently in operation as a case study. The inventory is mostly based on plant-specific data, extrapolated from on-site measurements regarding mechanical and biological operations (including anaerobic digestion and composting of digestate). The combined treatment of 46,929 tonnes of residual Municipal Solid Waste and 12,158 tonnes of source-sorted biowaste (as treated in 2010 at the plant) generates 24,550 tonnes CO2-eq as an impact on climate change, 69,943kg SO2-eq on terrestrial acidification and 19,929kg NMVOC-eq on photochemical oxidant formation, in a life-cycle perspective. On the contrary MBT induces environmental benefits in terms of fossil resource depletion, human toxicity (carcinogenic) and ecotoxicity. The results firstly highlight the relatively large contribution of some pollutants, such as CH4, emitted at the plant and yet sometimes neglected in the LCA of waste MBT. Moreover this study identifies 4 plant-specific operation conditions which drive the environmental impact potentials induced by MBT: the conditions of degradation of the fermentable fraction, the collection of gaseous flows emitted from biological operations, the abatement of collected pollutants and NOx emissions from biogas combustion. Finally the results underline the relatively large influence of the operations downstream the plant (in particular residuals incineration) on the environmental performance of waste MBT.

Environmental impacts of residual municipal solid waste incineration: a comparison of 110 French incinerators using a life cycle approach.

Incineration is the main option for residual Municipal Solid Waste treatment in France. This study compares the environmental performances of 110 French incinerators (i.e., 85% of the total number of plants currently in activity in France) in a Life Cycle Assessment perspective, considering 5 non-toxic impact categories: climate change, photochemical oxidant formation, particulate matter formation, terrestrial acidification and marine eutrophication. Mean, median and lower/upper impact potentials are determined considering the incineration of 1 tonne of French residual Municipal Solid Waste. The results highlight the relatively large variability of the impact potentials as a function of the plant technical performances. In particular, the climate change impact potential of the incineration of 1 tonne of waste ranges from a benefit of -58 kg CO2-eq to a relatively large burden of 408 kg CO2-eq, with 294 kg CO2-eq as the average impact. Two main plant-specific parameters drive the impact potentials regarding the 5 non-toxic impact categories under study: the energy recovery and delivery rate and the NOx process-specific emissions. The variability of the impact potentials as a function of incinerator characteristics therefore calls for the use of site-specific data when required by the LCA goal and scope definition phase, in particular when the study focuses on a specific incinerator or on a local waste management plan, and when these data are available.

Life Cycle Assessment of landfill biogas management: sensitivity to diffuse and combustion air emissions.

GOAL AND SCOPE: The life cycle inventory of landfill emissions is a key point in Life Cycle Assessment (LCA) of waste management options and is highly subject to discussion. Result sensitivity to data inventory is accounted for through the implementation of scenarios that help examine how waste landfilling should be modeled in LCA. METHOD: Four landfill biogas management options are environmentally evaluated in a Life Cycle Assessment perspective: (1) no biogas management (open dump), conventional landfill with (2) flaring, (3) combined heat and power (CHP) production in an internal combustion engine and (4) biogas upgrading for use as a fuel in buses. Average, maximum and minimum literature values are considered both for combustion emission factors in flares and engines and for trace pollutant concentrations in biogas. RESULTS: Biogas upgrading for use as a fuel in buses appears as the most relevant option with respect to most non-toxic impact categories and ecotoxicity, when considering average values for trace gas concentrations and combustion emission factors. Biogas combustion in an engine for CHP production shows the best performances in terms of climate change, but generates significantly higher photochemical oxidant formation and marine eutrophication impact potentials than flaring or biogas upgrading for use as a fuel in buses. INTERPRETATION AND DISCUSSION: However the calculated environmental impact potentials of landfill biogas management options depend largely on the trace gas concentrations implemented in the model. The use of average or extreme values reported in the literature significantly modifies the impact potential of a given scenario (up to two orders of magnitude for open dumps with respect to human toxicity). This should be taken into account when comparing landfilling with other waste management options. Also, the actual performances of a landfill top cover (in terms of oxidation rates) and combustion technology (in terms of emission factors) appear as key parameters affecting the ranking of biogas management options.