Life Cycle Assessment Literature Research Articles

Compiling life cycle inventories for wastewater-derived products

With the paradigm shift in wastewater management from pollutant removal to resource recovery, more wastewater-derived products are emerging from different recovery pathways. It is becoming increasingly important to understand the potential environmental impacts of these products through life cycle assessment (LCA). This study aims to compile life cycle inventories of wastewater-derived products from the perspective of the product end users (e.g., agricultural sector, packaging industry), and to explore the challenges of their compilation. Using inventories from wastewater resource recovery LCA literature, we compiled an attributional inventory (88 sets) and a consequential inventory (33 sets) of three categories of wastewater-derived products – phosphorus compounds, nitrogen compounds, and biopolymers. The two inventories differ by the choices of system boundary, how foreground systems are being modelled, and how co-products are being handled. We found that while there is a large body of literature related to wastewater resource recovery LCA, very few studies (29 out of 174 for the three categories of products) are suitable for end users to successfully compile inventories of derived products. The inventories were assessed by the technology readiness level assessment, the data quality assessment, and the cumulative energy demand indicator. The inventories can be used directly by end users or served as “screening” inventories for end users to prioritize data collection effort. The identified challenges of inventory compilation include diverse recovery settings, the absence of baseline scenarios, the multifunctional nature of wastewater treatment plants, the lack of inventory transparency and completeness, and low technology readiness level for some recovery pathways. While established or emerging approaches exist to address most of these challenges for end users, wastewater resource recovery LCA practitioners can enhance their assessments to be more end-user-oriented. This can be achieved by including baseline non-recovery scenarios, disclosing detailed life cycle inventory by system components, and assessing a wide variety of operating scenarios. Addressing some of these compilation challenges would enhance the comprehensiveness and quality of wastewater-derived product inventories.

Parametric Life Cycle Assessment of Nuclear Power for Simplified Models.

Electrifying the global economy is accepted as a main decarbonization lever to reach the Paris Agreement targets. The IEA's 2050 Net Zero transition pathways all involve some degree of nuclear power, highlighting its potential as a low-carbon electricity source. Greenhouse gas emissions of nuclear power reported in the life cycle assessment literature vary widely, from a few grams of CO2 equivalents to more than 100 g/kWh, globally. The reasons for such a variation are often misunderstood when reported and used by policymakers. To fill this gap, one can make LCA models explicit, exploring the role of the most significant parameters, and develop simplified models for the scientific community, policymakers, and the public. We developed a parametric cradle-to-grave life cycle model with 20 potentially significant variables: ore grade, extraction technique, enrichment technique, and power plant construction requirements, among others. Average GHG emissions of global nuclear power in 2020 are found to be 6.1 g CO2 equiv/kWh, whereas pessimistic and optimistic scenarios provide extreme values of 5.4-122 g CO2 equiv/kWh. We also provide simplified models, one per environmental impact indicator, which can be used to estimate environmental impacts of electricity generated by a pressurized water reactor without running the full-scale model.

Embodied life cycle impacts of lightweight building methods for affordable houses in the USA: Comparison of conventional, circular, and regenerative strategies

The transition to more circular practices in the construction sector offers an alternative to linear processes that are highly polluting and wasteful. Recent life cycle assessment (LCA) studies emphasize the relevance of the end-of-life scenario, highlighting its potential for impact reduction through circular strategies. There is an urgent need to fill the knowledge gap in the LCA literature on reducing the environmental impacts of affordable housing. Whole-building LCAs of three affordable homes built using a variety of lightweight construction methods in the southern United States were conducted to examine the environmental impacts of commonly used construction solutions for single-family affordable housing in the southern US and assess the extent to potential environmental impact mitigation through the introduction of additional circular strategies or the use of regenerative materials. In addition to the conventional as-built scenario, five hypothetical scenarios were considered in this study to evaluate the influence of different end-of-life options, namely, reduced recycling rates, increased recycling or reuse rates, and substitution of conventional insulation or finish materials with equivalent options from regenerative sources. The study aims to identify further opportunities for and limits to impact mitigation. The results show that the design and construction priorities should be (1) promoting proper end-of-life strategies for metals and wood-based materials, (2) replacing non-renewable materials with renewable wood or earth materials, and (3) increasing the reuse rate of materials and diverting construction waste. The study findings will support decision-making processes concerning the design and construction of low-impact affordable single-family homes and the development and implementation of affordable housing policies and regulations, resulting in greater environmental justice and a more equitable and sustainable built environment.

Life Cycle Assessment and Environmental Life Cycle costing of a unitised regenerative fuel cell stack

Life Cycle Assessment (LCA) and Environmental Life Cycle Costing (eLCC) are useful methods for evaluating the environmental, energy and economic performances of innovative energy storage technologies. By using these methods, the production process of a small Polymer Electrolyte Membrane Unitized Regenerative Fuel Cell (PEM-URFC) stack has been investigated, aiming to assess its environmental, energy and economic impacts at the early design stage and to identify the contributions of its various components on these impacts. Indeed, the PEM-URFC stack includes Critical Raw Materials that affect the product's sustainability. Results show that the highest contributions are associated with the platinum group metals used for the catalyst and, to a lesser degree, the materials and energy used for the bipolar plates and porous transport layers. However, considering that the datasets for representing the impacts of one of the electrocatalysts (Iridium Ruthenium Oxide) are still missing in LCA commercial databases and literature, a sensitivity analysis is performed assuming its impact to be similar to that of other Platinum Group Metals (PGMs) extracted with them (e.g., Platinum, Nickel, Palladium, etc.). The analysis shows a high difference in results due to data and methodological assumptions, making the assimilation of Iridium Ruthenium Oxide to Rhodium the worst scenario, increasing environmental impacts by 37.54 %, energy impacts by 40.48 % and environmental price by 45.08 %. Moreover, the study identified issues for applying life cycle thinking approaches on URFC devices that must be resolved in future studies (e.g., increase the reliability of catalyst inventory data or improve guidelines on energy storage technologies).

Review of Urban Building Types and Their Energy Use and Carbon Emissions in Life-Cycle Analyses from Low- and Middle-Income Countries.

Urbanization, slum redevelopment, and population growth will lead to unprecedented levels of residential building construction in "low- and middle-income" (LMI) countries in the coming decades. However, less than 50% of previous residential building life-cycle assessment (LCA) reviews included LMI countries. Moreover, all reviews that included LMI countries only considered formal (cement-concrete) buildings, while more than 800 million people in these countries lived in informal settlements. We analyze LCA literature and define three building types based on durability: formal, semiformal, and informal. These exhaustively represent residential buildings in LMI countries. For each type, we define dominant archetypes from across the world, based on construction materials. To address the data deficiency and lack of transparency in LCA studies, we develop a reproducibility metric for building LCAs. We find that the countries with the most reproducible studies are India, Sri Lanka, Turkey, Mexico, and Brazil. Only 7 out of 54 African countries have reproducible studies focused on either the embodied or use phase. Maintenance, refurbishment, and end-of-life phases are included in hardly any studies in the LMI LCA literature. Lastly, we highlight the necessity for studying current, traditional buildings to provide a benchmark for future studies focusing on energy and material efficiency strategies.

Evaluating the environmental performance of orange production in Veracruz, Mexico: A life cycle assessment approach

Mexico is the fifth largest producer of orange worldwide, and it is expected to increase its production in the following years. Environmental impacts of orange cultivation have been previously described in major orange-producing countries, except for Mexico. This paper aims to assess the environmental performance of orange production in Veracruz, Mexico's largest orange producer state, through the Life Cycle Assessment (LCA) methodology. A cradle-to-farm gate assessment was performed based on a functional unit of 1 ton of fresh orange. The system boundaries considered the environmental impacts of cultivation and harvesting of oranges, as well as impacts derived from the production of required inputs. Primary data was gathered from three municipalities within the Martinez and Tuxpan regions, and complemented using agricultural models to develop the life cycle inventory. Two farm categories were considered: the first based on the production system (conventional and organic), and the latter based on farm size (high and medium production); the obtained data was subsequently arranged into weighted averages. The environmental impacts were assessed using the CML-IA baseline impact methodology, plus the CED method and a water consumption quantification based on the life cycle inventories. Furthermore, a Principal Component Analysis (PCA) was performed to identify trends between systems and detect impact hotspots. Results indicate that conventional orange production has a higher impact than organic production in most of the assessed impacts, especially on GWP, AP, EP, and HTP, mainly caused by production and use of fertilizers. The environmental impacts related to upstream processes are the major contributors to the environmental impacts of organic orange production. This paper's contribution lies in broadening the LCA literature for fruit products in developing countries, characterizing orange producers based on crop system and farm size, and proposing the PCA tool for the interpretation of LCA results.

Internal causality in agri-food Life Cycle Assessments: Solving allocation problems based on feed energy utilization in egg production

Physical allocation in Life Cycle Assessment (LCA) should, ideally, be based on underlying causal relationships. While both cause-oriented and effect-oriented causality referred to in LCA literature are forms of external causality, internal causality addresses the actual flow of materials and inputs in a system – in other words, the real behaviour of the system under study. While a number or examples of allocation based on physical causality have been used in poultry LCAs, none of these represent the internal causality (the actual biological processes) in egg production. The current study remedies that gap by proposing such a method. Agri-food LCAs, in particular LCAs of livestock production, were used to identify existing physical allocation approaches consistent with internal causality. The most commonly used approach was found to be based on the allocation of feed energy to support the various physiological functions of the livestock species. A feed energy – Metabolizable Energy (ME) – utilization model for allocation in egg production LCAs is hence similarly proposed. Using the inventory of a previous LCA study of egg production in Canada, allocation ratios for eggs and spent hens were developed. Feed utilization models specific to each unit process were identified. The overall differences between ME utilization (∼95% eggs, 5% spent hens) and gross chemical energy content (92% eggs, 8% spent hens) for allocation were relatively small. Scenario analysis, however, showed that the allocation ratios can be considerably different if the causal relationship is interpreted differently. Differences over ∼20% was seen in a scenario which did not allocate between the co-products of each unit process in the system, but rather to the products at the end of a biological causal chain straddling multiple unit processes. The proposed approach is consistent with the interpretation of LCA as a natural sciences framework, and with the ISO 14044 multi-functionality hierarchy, because it reflects actual biological causality in egg production systems. The study results also underscore that practitioners should not only clearly justify their choice of allocation strategy, but also describe its application in detail, since small differences in methods can result in divergent outcomes.

A critical perspective on uncertainty appraisal and sensitivity analysis in life cycle assessment

AbstractIn this study, we review approaches for uncertainty appraisal in the life cycle assessment literature. We cover the acknowledgment of stochastic and epistemic uncertainty in uncertainty and sensitivity analysis and knowledge quality assessment, respectively. Consistent with previous works, our findings indicate that uncertainty is only appraised in a few studies on life cycle assessment. Most of these contributions cover only one of the phases of life cycle assessment, mainly the life cycle inventory phase. Less attention has been devoted to the phases of goal and scope definition and life cycle impact assessment. Additionally, in most studies, uncertainty analysis and sensitivity analysis have been applied independently, as it is wrongly assumed they cover different uncertainty spaces. We also identify the scope for improvement in the appraisal of epistemic uncertainty and the correct definition of the probability distribution of the uncertain factors. We conclude by highlighting studies in which sensible practices have been adopted, identifying open challenges, and suggesting possible ways forward.

Integration of Artificial Intelligence and Life Cycle Assessment Methods

Artificial Intelligence (AI) techniques support environmental tools based on the growing availability of data and information, aligning the concepts of data modeling and analysis. The Life Cycle Assessment (LCA) is an environmental tool that requires a large volume of data to measure the performance of a product and to simulate the proposed scenarios to improve its performance. This research reviewed studies using AI techniques and their intersection with LCA from data mining. This study identified some AI techniques used in LCA studies. However, there is a lack of LCA literature using AI techniques, despite the benefits of integrated modeling. The results show that different AI algorithms are used to build LCA models. The AI algorithms of the studies act from the identification of the problem to the solution stage, therefore the integration between AI and LCA makes it possible to build predictive models of machine learning to enable assertiveness in decision making.

The carbon footprint of dietary guidelines around the world: a seven country modeling study

BackgroundDo the environmental impacts inherent in national food-based dietary guidelines (FBDG) vary around the world, and, if so, how? Most previous studies that consider this question focus on a single country or compare countries’ guidelines without controlling for differences in country-level consumption patterns. To address this gap, we model the carbon footprint of the dietary guidelines from seven different countries, examine the key contributors to this, and control for consumption differences between countries.MethodsIn this purposive sample, we obtained FBDG from national sources for Germany, India, the Netherlands, Oman, Thailand, Uruguay, and the United States. These were used to structure recommended diets using 6 food groups: protein foods, dairy, grains, fruits, vegetables, and oils/fats. To determine specific quantities of individual foods within these groups, we used data on food supplies available for human consumption for each country from the UN Food and Agriculture Organization’s food balance sheets. The greenhouse gas emissions (GHGE) used to produce the foods in these consumption patterns were linked from our own database, constructed from an exhaustive review of the life cycle assessment literature. All guidelines were scaled to a 2000-kcal diet.ResultsDaily recommended amounts of dairy foods ranged from a low of 118 ml/d for Oman to a high of 710 ml/d for the US. The GHGE associated with these two recommendations were 0.17 and 1.10 kg CO2-eq/d, respectively. The GHGE associated with the protein food recommendations ranged from 0.03 kg CO2-eq/d in India to 1.84 kg CO2-eq/d in the US, for recommended amounts of 75 g/d and 156 g/d, respectively. Overall, US recommendations had the highest carbon footprint at 3.83 kg CO2-eq/d, 4.5 times that of the recommended diet for India, which had the smallest footprint. After controlling for country-level consumption patterns by applying the US consumption pattern to all countries, US recommendations were still the highest, 19% and 47% higher than those of the Netherlands and Germany, respectively.ConclusionsDespite our common human biology, FBDG vary tremendously from one country to the next, as do the associated carbon footprints of these guidelines. Understanding the carbon footprints of different recommendations can assist in future decision-making to incorporate environmental sustainability in dietary guidance.

Life cycle assessment: Blazing a trail for bioresources management

Abstract The life cycle assessment (LCA) is a well-established tool that has been used to provide data-driven analysis of environmental performances. LCA offers insights via selecting appropriate feedstocks, suitable technology, energy and environmental trade-off to be considered during the policy designing phase. In the present review, LCA analysis of each biomass based biorefinery and its impact assessment has been elaborated. The LCA literature clearly shows that transportation and manufacturing contribute majorly (up to 92.19%) to energy consumption and also the major global warming potential (GWP) was contributed by the electricity (86%) consumed by the biorefinery industry. Thus, utilizing greener energy sources such as hydroelectricity or bioelectricity for energy and transportation needs can help in minimizing the environmental impacts. Further, development of integrated biorefineries can significantly decrease greenhouse gas (GHG) emissions by 83% as compared to petroleum fuels and can fulfill the requirements for renewable fuel standards (RFS). The generation of multiple products at a single unit can help in adjusting the potential trade-offs and promoting environmentally beneficial processes during the designing phase for future refinery and energy systems. LCA is also a rational tool towards designing process blueprint for bioresources management through multi-products integrated biorefineries. It can be expanded further to cover the techno-economic, social, and health impacts in addition to environmental impacts (integrated sustainability assessment) for future integrated biorefineries and policy decisions.

Environmental analysis along the supply chain of dark, milk and white chocolate: a life cycle comparison

PurposeEnvironmental impact evaluation in the food sector is a key topic, due to both stricter legislations and higher consumer awareness towards sustainable choices. The case of chocolate is a remarkable example, owing to the increasing demand and the complex production process from cocoa beans to final bars. The present study aims at assessing the environmental impacts related to three chocolate types (dark, milk and white) through life cycle assessment (LCA) methodology.MethodsConsistent with food Product Category Rules (PCRs) and previous LCA literature, the study follows a cradle to grave approach. Among different raw material productions, it focuses above all on cocoa farming assuming three possible producer countries (i.e. Ghana, Ecuador and Indonesia), so that the influence of specific weather conditions and soil properties is underlined. Since the manufacturing step is supposed in the North Italian factory, different transport distances are also taken into account. Moreover, the work focuses on the possible use of several packaging materials and following disposal issues. In view of the open discussion about the most suitable functional unit in food sector, mass and energy amount approaches are compared.Results and discussionAlong chocolate supply chain, different phases are evaluated according to LCA methodology. Among analyzed producer countries: Indonesia monoculture case results to be the most impacting situation, due to an intensive use of agrochemicals; pesticides give a wide contribution in Ecuador, whereas Ghana is penalized by the highest water consumption. The transport of beans to manufacturing plant influences mostly the GWP, owing to long travelled distances. Considering the whole production process, cocoa derivatives and milk powder are the main contributors to every impact category. From packaging point of view, the best solution is the use of a single polypropylene layer. A sensitivity analysis is performed to check the validity of different allocation procedures: both mass and energy content allocations lead to similar results.ConclusionsThrough LCA methodology, the life cycle of dark, milk and white chocolate is compared. The study assesses different potential environmental impacts, assuming mass and energy content as possible functional units and references for allocation procedures. For all combinations of functional units and allocation rules, dark chocolate globally presents the best environmental performance, whereas the other two types have similar environmental impacts.

The environmental impact of Brazilian adults’ diet

Over the last years, dietary environmental impact and sustainable diets have been responsible for worldwide concern, especially in developed countries. Brazil is among the world’s largest greenhouse gas (GHG) emitters and the country does not have any specific food consumption measures to achieve the promise made at COP21. The main objective of our paper is analyzing the contribution of the Brazilian diet in terms of carbon, water and ecological footprint. We collected data in the National Dietary Survey for food intake and life cycle assessment literature database to estimate the composition of the current diet in Brazil. We used independent t tests and ANOVA tests to understand the differences among sociodemographic and income characteristics related to Brazilian adults’ diet. The environmental impact related to the Brazilian diet is very high, with beef consumption contributing to the largest share. Male household heads, with medium and low income, aged between 18 and 45 years old, with intermediate or less education level, who lives in rural areas in Midwest and Northeast regions were associated with higher environmental impact. Therefore, measures related to demand have great potential to reduce the environmental impact in Brazil.

Mitigation Life Cycle Assessment: Best Practices from LCA of Energy and Water Infrastructure That Incurs Impacts to Mitigate Harm

Climate change will require societal-scale infrastructural changes. Balancing priorities for water, energy, and climate will demand that approaches to water and energy management deviate from historical practice. Infrastructure designed to mitigate environmental harm, particularly related to climate change, is likely to become increasingly prevalent. Understanding the implications of such infrastructure for environmental quality is thus of interest. Environmental life cycle assessment (LCA) is a common sustainability assessment tool that aims to quantify the total, multicriteria environmental impact caused by a functional unit. Notably, however, LCA quantifies impacts in the form of environmental “costs” of delivering the functional unit. In the case of mitigation infrastructures, LCA results can be confusing because they are generally reported as the harmful impacts of performing mitigation rather than as net impacts that incorporate benefits of successful mitigation. This paper argues for defining mitigation LCA as a subtype of LCA to facilitate better understanding of results and consistency across studies. Our recommendations are informed by existing LCA literature on mitigation infrastructure, focused particularly on stormwater and carbon management. We specifically recommend that analysts: (1) use a performance-based functional unit; (2) be attentive to burden shifting; and (3) assess and define uncertainty, especially related to mitigation performance.

Environmental analyses to inform transitions to sustainable diets in developing countries: case studies for Vietnam and Kenya

Sustainable diets are an environmental, economic, and public health imperative, but identifying clear intervention points is challenging. Decision-making will require descriptive analyses from a variety of perspectives, even under the inevitable uncertainty introduced by limited data. This study uses existing data to provide a diet-level perspective on environmental impact from food production in the case study countries of Vietnam and Kenya. FAO food supply data at decadal time steps were used as a proxy for national average diets in Vietnam and Kenya. We combined these data with estimates of the greenhouse gas emissions (GHGE) and water use impact associated with producing food commodities. Generic GHGE factors were derived from a survey of the life cycle assessment literature. Country- and commodity-specific blue water use estimates were used, reflecting country-of-origin for import-dominated commodities. The AWARE characterization model was used to offer a diet-associated water scarcity footprint. Trends in diet-associated environmental impacts were interpreted in light of diet shifts, economic development trends, and other factors. Increasing per capita food supply in Vietnam, and in particular increases in meat, have led to rising diet-associated per capita GHGE. While supply of beef remains 5.2 times smaller than pork—the dominant meat—increases in beef demand in the past decade have resulted in it becoming second only to rice in contribution to diet GHGE. The water use and water scarcity footprint in Vietnam follow an increasing trend comparable to food supply. On the other hand, historically consistent levels of dairy and beef in Kenya dominate diet-level GHGE. Water use associated with the Kenyan diet shows marked increases between the 1990s and 2000s due to imports of wheat and rice from water-stressed regions. Environmental performance data for characteristic food production systems in these and other developing countries are needed to improve the representativeness and reliability of such assessments. Despite data limitations, the methods and results presented here may offer a fresh perspective in sustainable development policy deliberations, as they offer an entry point to linking environmental impact and consumption behaviors and can elucidate otherwise obscure or unexpected outcomes. A clear need emerges for further environmental analysis of dominant production systems within both Vietnam and Kenya.

Prospective study of lignin-based and recycled carbon fibers in composites through meta-analysis of life cycle assessments

Screening the life cycle assessment literature for information and recalculating extracted results was proven useful for identifying environmental challenges and opportunities in new, but related, contexts at early stages of technology development. The method was applied to carbon fiber reinforced polymers, a material of growing importance in industrial applications where a strong and/or light material is needed, such as in aircrafts and road vehicles. Many technology development efforts with the purpose of further improving such composite materials are on-going, in particular regarding the origin of carbon fibers. Using lignin as a bio-based feedstock and various recycling techniques have been suggested. However, these technologies do not yet exist at a scale that would enable a meaningful life cycle inventory, while the need for environmental guidance is urgent in order to ensure that only the more promising development paths are pursued before lock-in occurs. With a specific focus on the shift to lignin as a feedstock for carbon fibers and on recycled carbon fibers in composites, this article not only illustrates the type of information that can be obtained from mining and refining information from earlier life cycle assessment studies, but it also provides direct guidance on environmental opportunities and challenges specific for carbon fiber reinforced polymers. Thereby, it informs both technology development efforts and environmental assessment efforts. Amongst other things, the analysis reveals that an important factor behind the environmental impact of composites is the energy demand in carbonization of the carbon fibers and that both the shift to lignin-based and to recycled carbon fibers can potentially reduce this environmental impact. However, assessments of both lignin (as an output from a multifunctional process) and recycled carbon fibers (as an output from end-of-life activities) are connected to challenges related to the allocation of environmental impacts in an environmental assessment. Extracting and refining information from the literature proved useful for the specific task but remains to be tested in other fields of emerging technologies.

A unified framework of life cycle assessment

The dichotomy between the attributional approach and the consequential approach is one of the major unsettled questions in life cycle assessment (LCA). Debates continue on. Here, I suggest a different view that hopefully will help us move past the dichotomy and toward a unified framework for decision support. I argue the dichotomy is unnecessary. Attributional LCA, as reflected in how the conventional models like process- and input-output (IO)-based LCA have been applied, is simply a linear consequential modeling that establishes cause and effect through product supply chain. This is how economists see IO analysis, namely, a linear model based on Leontief production functions. There are other consequential and causal models, such as computable general equilibrium (CGE) and system dynamics (SD), that may have different production functions or focus on other aspects of the economy. These models have been increasingly integrated into LCA to estimate the environmental effects, impacts, or consequences of products, which is at the core of LCA. I further argue that as a field, we may be better off eliminating both terms: attributional fails to capture the essence of LCA and consequential is redundant. Likewise, economists did not call IO attributional and CGE consequential because both are consequential models, nor did they use the term consequential as that would be stating the obvious. I suggest LCA be unified around its goal to support decision-making, which requires estimating the impact of changes associated with a decision versus that without it (the counterfactual). This is the basic methodology adopted in many other fields. LCA then becomes an overarching framework that encompasses a suite of models, including our conventional IO/process-based LCA, to support different levels of decision-making related to products. Which distinguishes LCA from other fields of study is the focus on product systems. I also discuss, for the linear IO/process-based models, under what circumstances their estimates of the existing systems as an approximation of changes may be meaningful or misleading for decision-making. I further touch upon the importance of understanding the counterfactual, which has been largely neglected in LCA literature. For an LCA to support decision-making, (1) make explicit what the potential changes are and clearly define the scale of change and (2) derive range estimates to capture the high uncertainties in modeling complex systems and be willing to admit inconclusiveness. For decisions with potentially large impacts across sectors, a multi-model approach may be helpful.

Coupling attributional and consequential life cycle assessment: A matter of social responsibility

A long-running debate within the life cycle assessment literature concerns the appropriate uses for attributional and consequential forms of life cycle assessment. A recently published contribution to this debate suggests that social responsibility necessarily requires a consequential perspective, and that taking an attributional perspective is optional, but not necessary. The present paper critiques this suggestion by exploring two limitations with only taking a consequential perspective. First, consequential assessments are not additive, in the sense that when added they do not approximate to total aggregate environmental burdens. Second, consequential assessments are not suitable for creating an initial scope of responsibility, as the number of possible decisions available to an agent may be intractably large, and the notion of ‘role’ responsibility is not defined by specific decisions and consequences. This second limitation is derived from a previously identified parallel between attributional and consequential methods and the normative ethical theories of deontology and consequentialism. Based on the exploration of the two limitations, a coupled accounting solution is proposed which uses both consequential and attributional approaches for different but complementary purposes. The paper concludes by suggesting that although the debate on attributional versus consequential methods has occurred largely within the field of life cycle assessment, the proposed coupled accounting solution has broader applicability to other areas of social and environmental accounting.

Comparative Life Cycle Assessment of Silicon Nanowire and Silicon Nanotube Based Lithium Ion Batteries for Electric Vehicles

Silicon nanowires (SiNWs) and silicon nanotubes (SiNTs), with high specific capacity and low volume expansion during charging and discharging processes, have been recognized among the most promising anode materials for use in next-generation lithium ion batteries (LIBs). However, the life cycle impacts of SiNW-and SiNT-based LIBs are of grave concern due to the heavy use of toxic chemicals and potential nanoparticle emissions during their manufacturing processes. In this study, life cycle assessment (LCA) method is adopted to evaluate the environmental impacts of two battery packs, which are configured with the same capacity of 63.5 kWh to power a mid-size electric vehicle (EV). Both battery packs are based on a lithium nickel manganese cobalt oxide (LiNi1/3Mn1/3Co1/3O2, NMC) cathode, but one uses a SiNW anode, whereas the other uses a SiNT anode (NMC-SiNW and NMC-SiNT). Following a cradle-to-gate approach, the analysis is conducted based on LCA databases and literature. Results indicate that to obtain the same capacity, the NMC-SiNW LIB battery is with higher material consumptions and environmental impacts than the NMC-SiNT LIB battery. This study provides insights into life cycle impacts of SiNW-and SiNT-based LIBs and can be useful for understanding and improving the environmental performance of nanostructured Si-based LIBs for next-generation EV applications.

The environmental impact of packaging in food supply chains\u2014does life cycle assessment of food provide the full picture?

PurposeDue to the urgency and the magnitude of the environmental problems caused by food supply chains, it is important that the recommendations for packaging improvements given in life cycle assessment (LCA) studies of food rest on a balanced consideration of all relevant environmental impacts of packaging. The purpose of this article is to analyse the extent to which food LCAs include the indirect environmental impact of packaging in parallel to its direct impact. While the direct environmental impact of food packaging is the impact caused by packaging materials’ production and end-of-life, its indirect environmental impact is caused by its influence on the food product’s life cycle, e.g. by its influence on food waste and on logistical efficiency.MethodsThe article presents a review of 32 food LCAs published in peer-reviewed scientific journals over the last decade. The steps of the food product’s life cycle that contribute to the direct and indirect environmental impacts of packaging provide the overall structure of the analytical framework used for the review. Three aspects in the selected food LCAs were analysed: (1) the defined scope of the LCAs, (2) the sensitivity and/or scenario analyses and (3) the conclusions and recommendations.Results and discussionWhile in packaging LCA literature, there is a trend towards a more systematic consideration of the indirect environmental impact of packaging, it is unclear how food LCAs handle this aspect. The results of the review show that the choices regarding scope and sensitivities/scenarios made in food LCAs and their conclusions about packaging focus on the direct environmental impact of packaging. While it is clear that not all food LCAs need to analyse packaging in detail, this article identifies opportunities to increase the validity of packaging-related conclusions in food LCAs and provides specific recommendations for packaging-related food LCA methodology.ConclusionsOverall, we conclude that the indirect environmental impact of packaging is insufficiently considered in current food LCA practice. Based on these results, this article calls for a more systematic consideration of the indirect environmental impact of packaging in future food LCAs. In addition, it identifies a need for more packaging research that can provide the empirical data that many food LCA practitioners currently lack. In particular, LCA practitioners would benefit if there were more knowledge and data available about the influence of certain packaging characteristics (e.g. shape, weight and type of material) on consumer behaviour.