Quantified Uncertainties in Comparative Life Cycle Assessment: What Can Be Concluded?

Reducing the climate impact of residual waste treatment: A German case study on carbon management strategies

Climate neutrality goals require adapting the management of fossil carbon in waste management. This study evaluates the effectiveness of two key carbon management strategies addressing greenhouse gas (GHG) emissions from residual waste treatment, namely: pre-sorting residual waste in a material recovery facility to remove recyclable, carbon-rich materials (S_MRF) versus post-treatment of municipal solid waste incineration (MSWI) flue gas through carbon capture and storage (S_MSWI_CCS). Using residual waste management in Kassel, Germany, as a case study, GHG emissions are assessed for current and prospective scenarios, accounting for changes in waste inputs, material and energy systems, substitution choices, and uncertainties in treatment technology data. It is shown that MSWI in Kassel emits 857 kg of CO2 per t of wet residual waste, with 31 % fossil CO2. Carbon management strategies can reduce direct fossil CO2 emissions by 27 % (S_MRF) or 90 % (S_MSWI_CCS) and increase the net life cycle GHG savings of residual waste management by a factor of 1.6 (S_MRF) or 2.6 (S_MSWI_CCS), respectively. S_MSWI_CCS offers the highest potential to decrease the GHG footprint of residual waste management and is least sensitive to variations in waste composition, energy and material systems, and substitution choices. Discernibly higher net GHG savings of S_MRF compared to S_MSWI_CCS can only be observed if residual waste is rich in recyclables (low separate collection). Overall, this study highlights the utility of refined scenario, uncertainty and discernability analysis in accounting for local conditions and different settings as well as potential future changes to promote environmental decision support on waste management.

Global sensitivity analysis reduces data collection efforts in LCA: A comparison between two additive manufacturing technologies

Accounting for the environmental impacts in the design of technologies is becoming a necessity for manufacturers. Life cycle assessment (LCA) is a well-established method to quantify the environmental impacts of products and services through a holistic perspective and is increasingly used to support the eco-design of products and technologies. However, LCA generally faces an inherent issue with data availability. Given the constraints on both time and cost for collecting inventory data to feed the LCA model, a trade-off between data cost robustness is required with an efficient data collection strategy. The objective of this study is to develop a framework to prioritize data collection efforts in LCA using uncertainty analysis. This starts with a screening life cycle inventory analysis systematically informing all input parameters with uncertainty ranges. Monte Carlo analysis is then used to propagate the uncertainty through the model. Stochastic results are then compared with an acceptable confidence level set by the decision maker. This is followed by a global sensitivity analysis using Sobol' indices to rank different input parameters based on their contribution to the variability of the results. This paves the way for an iterative process prioritizing further data collection focusing on the most sensitive parameters. A case study comparing cold spray and wire arc additive manufacturing illustrates how to operationalize the framework. Learnings from the case study highlight the importance of defining the uncertainty ranges and the convergence criterion, where more work is needed in that domain.

Ascertaining the Environmental Advantages of Pavement Designs Incorporating Recycled Content through a Parametric and Probabilistic Approach

Reclaimed asphalt pavement (RAP) is a widely used end-of-life (EoL) material in asphalt pavements to increase the material circularity. However, the performance loss due to using RAP in the asphalt binder layer often requires a thicker layer, leading to additional material usage, energy consumption, and transportation effort. In this study, we developed a parametric and probabilistic life cycle assessment (LCA) framework to robustly compare various pavement designs incorporating recycled materials. Our framework is built upon thermodynamic and physical principles to reveal the complex relationship among the parameters. Mechanistic-Empirical Pavement Design Guide (MEPDG) models and Highway Development Management (HDM4) models are integrated into the framework to estimate pavement roughness and vehicle fuel consumption during the use phase. The pedigree approach and Monte Carlo simulation are integrated into the framework to reflect data uncertainty at the parameter level. We applied the framework to evaluate 66 Flemish motorway segments, revealing that using RAP in the binder layer with increased thickness does not necessarily guarantee lower greenhouse gas (GHG) emissions for pavement construction. However, it may lead to lower GHG emissions due to fuel savings when considering the use phase, highlighting the vital role of the use phase in pavement LCA. Our global sensitivity analysis highlights several contributors (out of 87 parameters) to GHG emissions variance depending on the LCA scope: fuel consumption during the use phase, transport distances, mass of fine aggregate, and machine power and machine productivity during pavement construction. Reducing uncertainties in these parameters can decrease the variance by up to 60%, enhancing discernibility by up to 11%. In conclusion, our parametric and probabilistic LCA framework provides a nuanced understanding when comparing various pavement designs incorporating recycled content, enabling robust decision-making through improved data quality.

Exploring resource recovery from diverted organics: Life cycle assessment comparison of options for managing the organic fraction of municipal solid waste

Diversion of the organic fraction of municipal solid waste (OFMSW) from landfills is increasing. Previous life cycle assessment studies have evaluated subsets of OFMSW management options, but conclusions are inconsistent, and none have evaluated diverse applications of material by-products. The primary objective of this work was to identify sustainability-based improvements to the selection, design, implementation, and operation of organics waste diversion management technologies. Process modeling and life cycle assessment were used to compare OFMSW composting, anaerobic digestion, and pyrolysis, with biochar used as a landfill cover, leachate treatment sorbent, and land applicant. Material and energy flows, calculated by newly developed models for the defined functional unit (1 kg MSW over a 20-year timeframe), were translated to environmental performance using ecoinvent and USLCI databases and TRACI method. Additionally, uncertainty, sensitivity, and scenario analyses were conducted to evaluate the implications of model uncertainties, design decisions, and resource recovery tradeoffs. OFMSW pyrolysis usually (65 % of uncertainty assessment simulations) had the best global warming performance mostly due to energy recovery and biochar's carbon sequestration benefit, which was independent of fate. Pyrolyzing the biosolids from OFMSW anaerobic digestion recovered the most energy and had the best performance in 34 % of uncertainty simulations. Material recovery amounts were large (e.g., more biochar was produced than required for novel uses) and warrant feasibility considerations. Global warming performance was more sensitive to uncertainty in carbon sequestration and primary energy production than in fertilizer offset, energy conversion, or heat offset approach. Practical implications include the potential for biochar supply to outweigh demand, and inconsistent revenue from the sale of recovered energy and carbon credits; future research could focus on evaluating the relative social and economic sustainability of the OFMSW management technologies.

Comparative Life Cycle Assessment of alternative winter salad value chains supplying the United Kingdom

Lettuce is an established food commodity in the UK increasingly facing supply challenges in winter due to adverse weather events and rising energy costs. We investigate whether an agroecologically grown salad mix of lettuce and underutilised leafy greens produced in the Azores, Portugal, could be part of a sustainable solution. We performed a Life Cycle Assessment to compare the environmental impacts of this salad mix with four other value chains for winter salad supply to the UK: conventional open-field lettuce production chains in Spain using (1) current irrigation practices; (2) 100 % desalinated irrigation water; or hydroponic controlled environment agriculture within the UK powered by (3) the national electricity mix; (4) 100 % wind-generated electricity. Results indicated that the leafy-greens agroecological value chain incurred the smallest environmental burdens across 7 to 11 of 16 impact categories studied. Substituting Spanish winter salad supply with agroecological leafy green production in the Azores, if well managed, could reduce many environmental burdens whilst diversifying leafy greens intake. Nevertheless, all winter value chains were associated with larger environmental burdens than conventional open-field production of lettuce in the UK summer, pointing to the importance of seasonal consumption and wider adoption of agroecological techniques to effectively reduce environmental impact.

A Life Cycle Assessment Study of the Impacts of Pig Breeding on the Environmental Sustainability of Pig Production

Lifecycle assessment (LCA) quantified changes in environmental impact categories (global warming, eutrophication, etc.) from 2021 to 2030 due to genetic trends in (re)production traits in pig lines of the breeding company Genus-PIC. The 2030 levels were projected with selection index theory based on weightings of traits in the breeding goals and genetic covariances among them. The projected improvement was 0.9% annually for most impact categories. Another LCA compared the impacts of 2021 North American pig production based on PIC genetics versus the industry average. Software openLCA converted material and energy flows to impact categories of frameworks ReCiPe-2016, PEF-3.1, and IPCC-2021. Flows came from data recorded by customers (1.1/4.7 million sows/finishing pigs) and by subscribers to a third-party data aggregator (1.3/9.1 million). PIC genetics have a 7-8% better impact than industry average for 13/18 categories of ReCiPe-2016, 19/25 of PEF-3.1, and all categories of IPCC-2001. Pig breeding delivers positive environmental outcomes as correlated responses to selection for profitability-oriented breeding goals. This trend is additive; technology development will increase it. Different investment levels in breeding population structure and technology and different operational efficiencies of breeding companies cause substantial differences in the environmental impact of pig production.

Waste LCA and the future

Life cycle assessment (LCA) models quantifying the environmental aspects of waste management have become an integral part of waste management decision-making over the last two decades and have provided ample knowledge on both environmental benefits and drawbacks in the way we handle waste. Waste management and LCA modelling of waste management systems will soon be challenged by profound changes necessary in our societies and sectors to meet sustainable development goals. Foreseen changes in energy, material, and nutrient provision will directly and indirectly affect waste management in terms of its operation and goals. This study reflects on anticipated changes in society and industrial sectors and how these changes may affect waste management and LCA modelling of waste management systems in terms of waste input, the modelling of technologies and systems and exchanges of energy, materials, and nutrients, as well as how it may affect impact assessment and the interpretation of results. The study provides practical recommendations for LCA modelling of future waste management systems, which will hopefully lead to robust assessments that can support decision-making in an evolving society subject to great changes.

Livestock waste management for energy recovery in Brazil: a life cycle assessment approach

Livestock farming has exerted intense environmental pressure on our planet. The high emissions to the environment and the high demands of resources for the production process have encouraged the search for decarbonization and circularity in the livestock sector. In this context, the objective of this study was to evaluate and compare the environmental performance of two different uses for biogas generated in the anaerobic digestion of animal waste, either for electricity generation or biomethane. For this purpose, a life cycle assessment approach was applied to evaluate the potential of anaerobic digestion as a management technology for three different livestock wastes, related to beef cattle, dairy, and sheep in the Brazilian animal production context. The results suggest that the treatment scenarios focusing on biomethane generation were able to mitigate the highest percentage of damages (77 to 108%) in the global warming category when compared to the scenarios without the use of anaerobic digestion (3.00·102 to 3.71·103 kgCO2 eq) or in the perspective of electricity generation (mitigation of 74 to 96%). In terms of freshwater eutrophication, the generation of electricity (- 2.17·10-2 to 2.31·10-3 kg P eq) is more favorable than the purification of biogas to biomethane (- 1.73·10-2 to 2.44·10-3 kg P eq), due to the loss of methane in the upgrading process. In terms of terrestrial ecotoxicity, all scenarios are very similar, with negative values (- 1.19·101 to - 7.17·102 kg 1,4-DCB) due to the benefit of nutrient recovery, especially nitrogen, associated with the use of digestate as fertilizer, which was one of the critical points in all scenarios. Based on these results, it is evident that proper management of all stages of the treatment life cycle is the key to decarbonization and circularity in livestock waste management. The biogas use does not present different effects on the environmental performance of the scenarios studied, demonstrating that the purpose should be chosen according to the needs of each plant or management system.

Stochastic Ex-Ante LCA under Multidimensional Uncertainty: Anticipating the Production of Undiscovered Microalgal Compounds in Europe

Due to their biodiversity, microalgae represent a promising source of high-value compounds that bioprospecting is aiming to reveal. Performing an ex-ante Life Cycle Assessment (LCA) to anticipate and potentially minimize the environmental burden associated with the European production of a bioprospected microalgal compound is subject to substantial and multi-factorial uncertainty as the compound remains undiscovered. Given that any microalgal strain could potentially host the compound of interest, the ex-ante LCA should consider this bioprospecting uncertainty together with the uncertainty on the technology and the production mix. Using a parameterized cultivation simulation and consequential LCA model and an extensive stochastic pseudo Monte Carlo approach, we define and propagate techno-operational, bioprospecting, and production mix uncertainties for a microalgal compound being currently bioprospected in Europe. We perform global sensitivity analysis using different sampling strategies to identify the main contributors to the total output variance. Overall, the uncertainty propagation allowed us to define and analyze the probabilistic scope for the potential environmental impacts in the emerging production of high-value microalgal compounds in Europe based on current knowledge. These findings can support policy-making as well as actors in the microalgal sector toward technological paths with lower environmental impact.

Ovalbumin production using Trichoderma reesei culture and low-carbon energy could mitigate the environmental impacts of chicken-egg-derived ovalbumin

Ovalbumin (OVA) produced using the fungus Trichoderma reesei (Tr-OVA) could become a sustainable replacement for chicken egg white protein powder-a widely used ingredient in the food industry. Although the approach can generate OVA at pilot scale, the environmental impacts of industrial-scale production have not been explored. Here, we conducted an anticipatory life cycle assessment using data from a pilot study to compare the impacts of Tr-OVA production with an equivalent functional unit of dried chicken egg white protein produced in Finland, Germany and Poland. Tr-OVA production reduced most agriculture-associated impacts, such as global warming and land use. Increased impacts were mostly related to industrial inputs, such as electricity production, but were also associated with glucose consumption. Switching to low-carbon energy sources could further reduce environmental impact, demonstrating the potential benefits of cellular agriculture over livestock agriculture for OVA production.

Setting Thresholds to Define Indifferences and Preferences in PROMETHEE for Life Cycle Sustainability Assessment of European Hydrogen Production

The Life Cycle Sustainability Assessment (LCSA) is a proven method for sustainability assessment. However, the interpretation phase of an LCSA is challenging because many different single results are obtained. Additionally, performing a Multi-Criteria Decision Analysis (MCDA) is one way—not only for LCSA—to gain clarity about how to interpret the results. One common form of MCDAs are outranking methods. For these type of methods it becomes of utmost importance to clarify when results become preferable. Thus, thresholds are commonly used to prevent decisions based on results that are actually indifferent between the analyzed options. In this paper, a new approach is presented to identify and quantify such thresholds for Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) based on uncertainty of Life Cycle Impact Assessment (LCIA) methods. Common thresholds and this new approach are discussed using a case study on finding a preferred location for sustainable industrial hydrogen production, comparing three locations in European countries. The single LCSA results indicated different preferences for the environmental, economic and social assessment. The application of PROMETHEE helped to find a clear solution. The comparison of the newly-specified thresholds based on LCIA uncertainty with default thresholds provided important insights of how to interpret the LCSA results regarding industrial hydrogen production.

Does Circular Reuse of Chickpea Cooking Water to Produce Vegan Mayonnaise Reduce Environmental Impact Compared with Egg Mayonnaise?

Consumers are increasingly asking for foods that are healthier, more humane, and environmentally sustainable. Recently, chickpea cooking water—aquafaba—has gained popularity as a potential egg substitute that complies with these criteria. However, research on the environmental impact of this ingredient is lacking. We performed a comparative attributional life cycle assessment (LCA) of mayonnaise made with aquafaba as the emulsifying agent, and traditional mayonnaise made with egg yolk. The vegan mayonnaise was found not to be as environmentally sustainable as the egg-based product. The vegan mayonnaise had a significantly (p < 0.05) lower impact across 4 categories, but a significantly higher impact across 8 categories out of 16, including climate change and resource-use-energy-carriers. The majority of categories under which vegan mayonnaise underperformed were related to the electricity needed for aquafaba processing. These impacts can be mitigated with a “cleaner” electricity grid, or onsite renewable electricity generation. Substituting the Mexican grid, where the aquafaba is currently processed, for the Canadian grid, where the mayonnaise is produced, reduced the carbon footprint of the vegan mayonnaise by 37%, making it similar to the egg-based product. As sunflower oil production was linked to extensive environmental burdens, we performed additional sensitivity analyses around oil processing, sunflower production, and other vegetable oils. Our study shows that substituting egg yolk with aquafaba could cause an increase in the environmental footprint of mayonnaise due to high processing costs, illustrating that vegan options do not always have a smaller environmental footprint, and can represent a trade-off in their comparatively more humane and healthier offer.

Life cycle assessment of nutrient recycling from wastewater: A critical review

Recovering resources from wastewater systems is increasingly being emphasised. Many technologies exist or are under development for recycling nutrients such as nitrogen and phosphorus from wastewater to agriculture. Planning and design methodologies are needed to identify and deploy the most sustainable solutions in given contexts. For the environmental sustainability dimension, life cycle assessment (LCA) can be used to assess environmental impact potentials of wastewater-based nutrient recycling alternatives, especially nitrogen and phosphorus recycling. This review aims to evaluate how well the LCA methodology has been adapted and applied for assessing opportunities of wastewater-based nutrient recycling in the form of monomineral, multimineral, nutrient solution and organic solid. We reviewed 65 LCA studies that considered nutrient recycling from wastewater for agricultural land application. We synthesised some of their insights and methodological practices, and discussed the future outlook of using LCA for wastewater-based nutrient recycling. In general, more studies suggested positive environmental outcomes from wastewater-based nutrient recycling, especially when chemical inputs are minimised, and source separation of human excreta is achieved. The review shows the need to improve methodological consistency (e.g., multifunctionality, fertiliser offset accounting, contaminant accounting), ensure transparency of inventory and methods, consider uncertainty in comparative LCA context, integrate up-to-date cross-disciplinary knowledge (e.g., agriculture science, soil science) into LCA models, and consider the localised impacts of recycled nutrient products. Many opportunities exist for applying LCA at various scales to support decisions on wastewater-based nutrient recycling - for instance, performing "product perspective" LCA on recycled nutrient products, integrating "process perspective" LCA with other systems approaches for selecting and optimising individual recovery processes, assessing emerging nutrient recovery technologies and integrated resource recovery systems, and conducting systems analysis at city, national and global level.

Life Cycle Assessment for the Design of Chemical Processes, Products, and Supply Chains

Design in the chemical industry increasingly aims not only at economic but also at environmental targets. Environmental targets are usually best quantified using the standardized, holistic method of life cycle assessment (LCA). The resulting life cycle perspective poses a major challenge to chemical engineering design because the design scope is expanded to include process, product, and supply chain. Here, we first provide a brief tutorial highlighting key elements of LCA. Methods to fill data gaps in LCA are discussed, as capturing the full life cycle is data intensive. On this basis, we review recent methods for integrating LCA into the design of chemical processes, products, and supply chains. Whereas adding LCA as a posteriori tool for decision support can be regarded as established, the integration of LCA into the design process is an active field of research. We present recent advances and derive future challenges for LCA-based design.

Methodological review and detailed guidance for the life cycle interpretation phase

Life cycle interpretation is the fourth and last phase of life cycle assessment (LCA). Being a "pivot" phase linking all other phases and the conclusions and recommendations from an LCA study, it represents a challenging task for practitioners, who miss harmonized guidelines that are sufficiently complete, detailed, and practical to conduct its different steps effectively. Here, we aim to bridge this gap. We review available literature describing the life cycle interpretation phase, including standards, LCA books, technical reports, and relevant scientific literature. On this basis, we evaluate and clarify the definition and purposes of the interpretation phase and propose an array of methods supporting its conduct in LCA practice. The five steps of interpretation defined in ISO 14040-44 are proposed to be reorganized around a framework that offers a more pragmatic approach to interpretation. It orders the steps as follows: (i) completeness check, (ii) consistency check, (iii) sensitivity check, (iv) identification of significant issues, and (v) conclusions, limitations, and recommendations. We provide toolboxes, consisting of methods and procedures supporting the analyses, computations, points to evaluate or check, and reflective processes for each of these steps. All methods are succinctly discussed with relevant referencing for further details of their applications. This proposed framework, substantiated with the large variety of methods, is envisioned to help LCA practitioners increase the relevance of their interpretation and the soundness of their conclusions and recommendations. It is a first step toward a more comprehensive and harmonized LCA practice to improve the reliability and credibility of LCA studies.

Life Cycle Assessment of Bitcoin Mining

This study estimates the environmental impact of mining Bitcoin, the most well-known blockchain-based cryptocurrency, and contributes to the discussion on the technology's supposedly large energy consumption and carbon footprint. The lack of a robust methodological framework and of accurate data on key factors determining Bitcoin's impact have so far been the main obstacles in such an assessment. This study applied the well-established Life Cycle Assessment methodology to an in-depth analysis of drivers of past and future environmental impacts of the Bitcoin mining network. It was found that, in 2018, the Bitcoin network consumed 31.29 TWh with a carbon footprint of 17.29 MtCO₂-eq, an estimate that is in the lower end of the range of results from previous studies. The main drivers of such impact were found to be the geographical distribution of miners and the efficiency of the mining equipment. In contrast to previous studies, it was found that the service life, production, and end-of-life of such equipment had only a minor contribution to the total impact, and that while the overall hashrate is expected to increase, the energy consumption and environmental footprint per TH mined is expected to decrease.

Sustainability of safe foods: Joint environmental, economic and microbial load reduction assessment of antimicrobial systems in U.S. beef processing

Various antimicrobial interventions are applied sequentially in the beef processing industry to reduce microbial load on beef products by using intensive inputs (e.g., chemicals, energy), high strength wastewater, and potentially result in meat discoloration. This study serves as the first analysis to jointly evaluate environmental and economic assessment with its microbial load reduction of proposed antimicrobial systems in the U.S. beef processing industry to identify relatively sustainable systems that minimize environmental and economic impacts while providing microbial safe meat. Specifically, forty potential sequential antimicrobial systems were proposed and evaluated from three perspectives: microbial load reduction, environmental, and economic impacts, by meta-analysis, life cycle assessment, and operational cost analysis orderly. The results show that the antimicrobial systems applying steam pasteurization during the main intervention offer high microbial load reduction (>4.2 log CFU/cm² reduction from a hypothetical initial contamination at 5.0 log CFU/cm²). Human health impact (31.0 to 65.6%) and ecosystem toxicity (3.6 to 12.5%), eutrophication (11.9 to 15.5%) and global warming (6.4 to 22.2%) are the main contributors to the overall environmental single score among the forty antimicrobial systems. Antimicrobial chemicals (up to 82.8%), wastewater treatment (up to 12.7%), and natural gas (up to 10.7%) are the three major drivers of operational cost for sanitizing 1000 kg hot standard carcass weight (HSCW). Devalued (discolored) meat due to contact with heat from steam pasteurization or hot water wash has a considerable increase in economic ($4.5/1000 HSCW) and environmental (especially at farm stage) impacts. Certain antimicrobial systems (e.g., water wash followed by steam pasteurization) were found to be more promising with satisfactory effectiveness, better environmental and cost performance under uncertainty (1000 Monte Carlo simulations). Results from this study can guide the U.S. beef processing industry to advance sustainability while protecting human health from foodborne illness.

Enhancing waste management strategies in Latin America under a holistic environmental assessment perspective: A review for policy support

Waste remains a serious environmental and human health hazard in developing nations, including those in Latin America and the Caribbean (LA&C). Despite important breakthroughs in waste management in LA&C, the region still faces many challenges that require special attention, such as the existence of uncontrolled open dumpsters (33%) or the low recovery rates of waste fractions (below 4%). Moreover, the adoption of sophisticated waste management technologies, such as incineration or anaerobic digestion, is still lagging. This review paper provides environmentally-sound and relevant policy support for municipal solid waste management stakeholders through a critical review of the current situation of the waste management sector in LA&C from an environmental perspective. Thereafter, Life Cycle Assessment (LCA) bibliography linked to waste management, namely collection, sorting, recycling and landfilling applications and technologies worldwide, is used in order to understand potential alternative waste management strategies in LA&C, as well as the potential environmental benefits that could be attained. Finally, based on the holistic review and analysis, the adoption of more sophisticated technologies in landfill sites (e.g. landfill gas flaring), waste-to-energy, as well as higher recycling rates, would enhance waste management in the region and mitigate environmental impacts. A holistic view to support policy formulations, including climate action, for the adoption of integrated waste management strategies in LA&C is imperative.

Aligning sustainability assessment with responsible research and innovation: Towards a framework for Constructive Sustainability Assessment

Emerging technologies are increasingly promoted on the promise of tackling the grand challenge of sustainability. A range of assessment and governance approaches seek to evaluate these claims, but these tend to be applied disparately and lack widespread operationalisation. They also face specific challenges, such as high levels of uncertainty, when it comes to emerging technologies. Building and reflecting on both theory and practice, this article develops a framework for Constructive Sustainability Assessment (CSA) that enables the application of sustainability assessments to emerging technologies as part of a broader deliberative approach. In order to achieve this, we discuss and critique current approaches to analytical sustainability assessment and review deliberative social science governance frameworks. We then develop the conceptual basis of CSA - blending life-cycle thinking with principles of responsible research and innovation. This results in four design principles - transdisciplinarity, opening-up, exploring uncertainty and anticipation - that can be followed when applying sustainability assessments to emerging technologies. Finally, we discuss the practical implementation of the framework through a three-step process to (a) formulate the sustainability assessment in collaboration with stakeholders, (b) evaluate potential sustainability implications using methods such as anticipatory life-cycle assessment and (c) interpret and explore the results as part of a deliberative process. Through this, CSA facilitates a much-needed transdisciplinary response to enable the governance of emerging technologies towards sustainability. The framework will be of interest to scientists, engineers, and policy-makers working with emerging technologies that have sustainability as an explicit or implicit motivator.

Review of Methodological Choices in LCA-Based Textile and Apparel Rating Tools: Key Issues and Recommendations Relating to Assessment of Fabrics Made From Natural Fibre Types

Life cycle assessment (LCA) is a key tool for determining environmental impacts for textiles and apparel and is the basis for the publicly available Higg Material Sustainability Index (MSI) developed by the Sustainable Apparel Coalition (SAC). This paper reviews and evaluates the Higg MSI with respect to rating of fabrics made from natural fibre types, with the aim of providing a constructive analysis of methodological issues identified by comparison with the International Standards and LCA guidelines. The major issues identified by the review were: (1) lack of sufficient guidance for comparative analysis and public disclosure; (2) incomplete system boundaries and the choice of functional unit; (3) the choice of attributional LCA methods and variable methods applied for handling multi-functionality; (4) use of generalised data and small datasets, without reported sensitivity or uncertainty; (5) exclusion of important impact categories, choice of LCIA methods and lack of coverage of non-LCA assessed issues; and (6) the choice of the weighting and normalisation approach. This review found that the provision of, and adherence to the appropriate standards and best practice in LCA would rectify most of these issues. To achieve the laudable aims of the Higg MSI, further development and refinement is needed to ensure robust information is provided to improve the sustainability of textiles.

Greenhouse gas savings and energy balance of sewage sludge treated through an enhanced intermediate pyrolysis screw reactor combined with a reforming process

A life cycle thinking approach focusing on energy and greenhouse gas savings has been applied to study the potential for energy recovery and organic matter reclamation from Waste Activated Sludge produced in Waste Water Treatment Plants by means of a catalytic thermo-chemical process. A generic Basic Sludge Processing line has been modelled following common waste water and sludge treatment stages found in several European plants. This has served to identify and divide generic sludge treatment units in order to compare the performance of different industrial configurations where a specific thermo-chemical technology treatment unit and related cogeneration was substituted or added to reference units. The considered technology is an enhanced intermediate pyrolysis screw reactor combined with a reforming process known as Thermo-Catalytic Reforming allowing for conversion of sewage sludge into energy carriers and reclamation of organic substances in the form of charcoal (biochar). In order to study the greenhouse gas savings, a calculator tool complying with Directive 2009/28/EC has been adopted. Results show that substantial benefits in terms of energy production and greenhouse gas emissions reduction of a sludge-to-energy system are expected if the secondary sludge is directly treated with the Thermo-Catalytic Reforming process, without an intermediate anaerobic digestion step.

A tool to guide the selection of impact categories for LCA studies by using the representativeness index

Understanding the environmental profile of a product computed from the Life Cycle Assessment (LCA) framework is sometimes challenging due to the high number of environmental indicators involved. The objective here, in guiding interpretation of LCA results, is to highlight the importance of each impact category for each product alternative studied. For a given product, the proposed methodology identifies the impact categories that are worth focusing on, relatively to a whole set of products from the same cumulated database. The approach extends the analysis of Representativeness Indices (RI) developed by Esnouf et al. (2018). It proposes a new operational tool for calculating RIs at the level of impact categories for a Life Cycle Inventory (LCI) result. Impact categories and LCI results are defined as vectors within a standardized vector space and a procedure is proposed to treat issues coming from the correlation of impact category vectors belonging to the same Life Cycle Impact Assessment (LCIA) method. From the cumulated ecoinvent database, LCI results of the Chinese and the German electricity mixes illustrate the method. Relevant impact categories of the EU-standardized ILCD method are then identified. RI results from all products of a cumulated LCI database were therefore analysed to assess the main tendencies of the impact categories of the ILCD method. This operational approach can then significantly contribute to the interpretation of the LCA results by pointing to the specificities of the inventories analysed and for identifying the main representative impact categories.