Purpose
The paper contributes to the S-LCA impact assessment by understanding its maturity level to identify each characterization model’s good practices and limitations.
Method
Our research analyzes ...the S-LCIA type II (impact pathway) models’ current state of the art through a systematic review. To this end, we identified publications through international databases without period restriction up to 2020. Gray literature, theoretical propositions, and papers covering solely case studies of former developed models were not included. Among the 102 papers identified, only 14 papers presented type II modeling. These models were evaluated considering the following criteria and sub-criteria: (i) scope coverage (contextualization, time lag, and data level), (ii) scientific robustness (presentation of cause-and-effect chain, transparency, and accessibility), and (iii) characterization factor (CF) (existence, feasibility of regionalized CFs, and presence of uncertainty or sensitivity analysis). Each criterion is composed of sub-criteria related to desirable characteristics. We classified models on scales comprising two or three levels for each sub-criterion.
Results and discussion
We noticed some models need to provide clear cause-and-effect chains, relationships with social sciences, and measurement models are not always explicit. Most of them do not present ready-to-use characterization factors, and only a few models consider the time lag between cause and effect. Finally, several models are not always connected to company data. Based on the results, we provide recommendations for impact modeling in S-LCIA to support life cycle social and sustainability assessment.
Conclusions
Despite advances in S-LCIA impact pathway modeling, there are necessary improvements to support S-LCA. We identified good practices, but no model presents all characteristics. Even if the criteria proposed to evaluate the type II models are only partially comprehensive, this framework supports S-LCIA model development by listing desirable characteristics and recommended good practices. We advise (i) including the model’s usage limitations, (ii) using time series analysis to include the time lag between cause and effect or to inform if the effect is immediate, (iii) and using company or sector data to develop the characterization factors. The characterization models with links to social sciences, the cause-effect chain, and the reproducibility of the measurement model can improve the models’ clarity. At last, providing contextualized CFs would support mainstream S-LCA.
The production of battery materials has been identified as the main contributor to the greenhouse gas (GHG) emissions of lithium-ion batteries for automotive applications. Graphite manufacturing is ...characterized by energy intense production processes (including extraction), mainly being operated in China with low energy prices and a relatively high GHG emission intensity of electricity generation.
Industrial scale primary data related to the production of battery materials lacks transparency and remains scarce in general. In particular, life cycle inventory datasets related to the extraction, refining and coating of graphite as anode material for lithium-ion batteries are incomplete, out of date and hardly representative for today's battery applications. Nevertheless, primary life cycle inventory data of battery materials like graphite, produced on an industrial scale are crucial for a robust evaluation of batteries for electric vehicles, material sourcing and development of robust decarbonization strategies.
This paper addresses this issue by first providing a comprehensive overview of the existing graphite datasets and their original sources, and outlining the reasons for wide variations of reported environmental impact results. Furthermore, this paper aims at closing existing data gaps by providing transparent primary data from a Chinese graphite producer from 2019 and assessing the environmental impacts (cradle-to-gate) in form of a life cycle assessment (LCA) for a vertically integrated graphite production. The life cycle inventory covers material, water, energy flows and direct emissions associated with the production of natural graphite anode material for an automotive battery application and associated transport activities along the supply chain. The results of the LCA show that the production of 1000 kg of natural graphite anode material has a global warming potential (GWP) of approximately 9616 kg CO2eq. The subsequent uncertainty analysis in the form of a Monte-Carlo-Analysis with 10000 runs reveals that the 95% confidence interval is in the range between 9297 and 9940 kg CO2eq. This value is more than four times higher than the reported GWP of battery-grade graphite in the ecoinvent database version 3.7.1.
Display omitted
•Literature review map for existing graphite studies.•LCA of graphite based on primary industrial scale data.•Monte-Carlo-Simulation to support decision-making based on results.
Pyrolysis of sewage sludge was selected as a potential disposal method that provides biochar and bio-oil. An intrinsic problem of sewage sludge is the high concentration of heavy metals, which is ...retained in the char. This study aims to compare both slow and fast pyrolysis char and their leachability of heavy metals for agricultural land use, as defined by the U.S. EPA regulation. Slow pyrolysis biochar yields decreased from 51.6 wt% at 300 °C to 32 wt% at 500 °C. Similarly, fast pyrolysis biochar yields also decreased from 30 wt% at 400 °C to 26 wt% at 500 °C. The higher heating value reduced for the chars produced at high temperatures because of greater ash content. The maximum higher heating value on ash free basis was 34.6 MJ kg−1 for the fast pyrolysis char at 500 °C. We developed a new method for the calculation of the enthalpy of pyrolysis (2.2 MJ kg−1), which was used to create a complete energy balance for the pyrolysis of sewage sludge. We performed an economic analysis for a typical sewage sludge pyrolysis plant processing 2.1 ton of dry solids per hour. For such a scenario we found that the annual total capital investment and annual expenditure were 13.5 million CAD and 1.32 million CAD, respectively. An environmental life-cycle assessment determined that pyrolysis of sewage sludge with use of the biochar as a substitute fuel in a cement kiln had the least impacts on global warming potential and fresh water ecotoxicity.
•Self-sustainable operation possible with a sludge water content of up to 78%.•Slow pyrolysis biochars had lower leachability of heavy metals.•Potential for long term carbon sequestration in the biochar.•Pyrolysis showed positive environmental benefits when compared to incineration.
With the global energy crisis and the increasing severity of environmental pollution, promoting the exploitation of clean energy, especially the renewable energy, has become an effective way to ...reduce the consumption of fossil fuels and the emissions of carbon dioxide. Based on the facts above, this paper carries out a comprehensive analysis of the carbon emissions during the whole life cycle of wind power project according to the life-cycle assessment theory, and both the construction of wind farm project and the corresponding networking project are taken into consideration. Then, the Life cycle inventory of wind power project is delivered to carry out the calculation of carbon emissions during the project’s whole life cycle. Finally, the 49.5 MW wind power project in Shi-san-jian-fang area of Xinjiang is employed for empirical analysis to discuss the project’s carbon intensity and the potential of emission reductions. The result shows that the carbon intensity of this wind power project is 4.429 g/kWh and the potential for emission reductions throughout its life cycle reaches 2.0416 million tons in theory, which means wind power project owes huge potential for emission reductions compared with general coal-fired stations.
•A LCA analysis of a wind power project in China was conducted.•Both the wind power plant and the corresponding networking project were involved.•The carbon emission calculation model and Life cycle inventory were established.•Carbon emission intensity and emission reduction potential were analyzed.
Supply chains become increasingly globalized. Multi-regional input-output databases contain all the information to assess impacts along the value chain, but standard calculation routines to track the ...impacts of any sector along the global upstream and downstream value chain are missing. Mapping the impacts of materials has been a particular challenge owing to difficulties with double-counting. This is attributed to the strong intertwining of the material supply chain meaning that different materials occur in the supply chains of other materials. Here, we present a new method which can be applied to any MRIO system to track the impacts of any sector or region without double-counting upstream and downstream the global value chain. We apply this approach to EXIOBASE3 and implement a cutting-edge set of regionalized environmental impact categories and socio-economic indicators. Applied to global material production, our method shows that the issue of double-counting (prevented in this study) would overestimate global impacts of materials by up to 30%. In contrast, assessing only the direct impacts would lead to an underestimation by ~20%. Our evaluation further reveals that 25–35% of global material-related impacts are embodied in trade among ten world regions. Thereby, we identify the major international trade relations of key materials and found a clear trend of industrialized nations causing impacts in less developed economies. It was further revealed that during 1995–2011, the share of materials in total global climate change impacts has remained almost constant at ~50%, but total impacts have significantly increased for minerals and fossils. Our results demonstrate the importance for improved environmental policy strategies that target several stages of the global value chain. The methodology is provided as Matlab tool and can be applied to any material, industrial sector and region to track the related impacts upstream and downstream the global value chain.
Display omitted
•New tool analyzes the environmental impacts of any sector without double-counting.•Sector impacts can be tracked upstream and downstream the global value chain.•Previous methods would have overestimated 30% of the impacts of materials (EXIOBASE3).•A third of global material-related impacts is embodied in trade among ten world regions.•Minerals and fossils show the strongest increase in climate change impacts since 1995.
Display omitted
•This study quantifies the nexus as energy intensity and greenhouse gas potential.•Baseline water stress and return flow ratio are identified as water risks.•Source water ...accessibility significantly contributes to variations in the nexus.•Water risks have little impact on the nexus of wastewater systems.•Study on the nexus is suggested to be conducted at regional levels.
The importance of the interdependence between water and energy, also known as the water-energy nexus, is well recognized. The water-energy nexus is typically characterized in resource use efficiency terms such as energy intensity. This study aims to explore the quantitative results of the nexus in terms of energy intensity and environmental impacts (mainly greenhouse gas emissions) on existing water systems within urban water cycles. We also characterized the influence of water risks on the water-energy nexus, including baseline water stress (a water quantity indicator) and return flow ratio (a water quality indicator). For the 20 regions and 4 countries surveyed (including regions with low to extremely high water risks that are geographically located in Africa, Australia, Asia, Europe, and North America), their energy intensities were positively related to the water risks. Regions with higher water risks were observed to have relatively higher energy and GHG intensities associated with their water supply systems. This mainly reflected the major influence of source water accessibility on the nexus, particularly for regions requiring energy-intensive imported or groundwater supplies, or desalination. Regions that use tertiary treatment (for water reclamation or environmental protection) for their wastewater treatment systems also had relatively higher energy and GHG emission intensities, but the intensities seemed to be independent from the water risks. On-site energy recovery (e.g., biogas or waste heat) in the wastewater treatment systems offered a great opportunity for reducing overall energy demand and its associated environmental impacts. Future policy making for the water and energy sectors should carefully consider the water-energy nexus at the regional or local level to achieve maximum environmental and economic benefits. The results from this study can provide a better understanding of the water-energy nexus and informative recommendations for future policy directions for the effective management of water and energy.
Stocks of fixed capital play a vital role in fulfilling basic human needs and facilitating industrial production. Their build‐up requires great quantities of energy and materials, and generates ...greenhouse gas emissions and other pollution. Capital stocks influence economic production and environmental pollution through their construction and over subsequent decades through their use. We perform an environmental footprint analysis of total consumption, capital investment, and capital consumption in the United States for 2007 and 2012. In 2012, capital consumption accounted for 13%, 19%, and 40% of total carbon, energy, and material footprints, respectively. Housing, federal defense, state and local government education and other services (including household consumption of roads), personal transport fuels, and hospitals are the consumption sectors with largest capital footprints. These sectors provide fundamental needs of shelter, transport, education, and health, underlying the importance of capital services. Endogenizing capital causes the biggest proportional increase to footprints of sectors with low environmental multipliers. This work builds upon existing input‐output models of production and consumption in the United States, and provides a capital‐inclusive database of carbon, energy, and material footprints and multipliers for 2007 and 2012. This article met the requirements for a gold – gold JIE data openness badge described at http://jie.click/badges.
Anthropogenic greenhouse gas (GHG) emissions are a major factor influencing climate change. The application of biochar as a soil amendment may be an effective way to reduce GHG emissions. Life cycle ...assessment (LCA) is widely used to assess the impact of biochar as a soil amendment on GHG emissions. The methodology is effective in assessing the impacts of the various stages of the biochar life cycle on GHG emissions. However, because of the diversity of biochar types, it is difficult to summarize the regularity of biochar life cycle impacts on GHG emissions. This paper summarizes the pathways of biochar's effect on GHG emissions and in-depth analyzes the mechanism of biochar's influence on GHG emissions from the perspective of biochar properties. Finally, the review comprehensively analyzes the effects of different types of biochar feedstock on GHG emissions at the stages of feedstock pretreatment, preparation, and application of the life cycle. The conclusions are as follows: (1) Biochar affects GHG emissions in three ways: feedstock supply, pyrolysis process, and application process. (2) The impact of biochar on GHG emissions is influenced by a combination of the physicochemical properties of biochar. (3) Biochar has a positive impact (feedstock pretreatment stage and preparation stage) or a negative impact (application stage) on life cycle GHG emissions. (4) The carbon sequestration capacity of biochar varies by feedstock type. The ranking of carbon sequestration capacity is waste wood biochar (WWB) > crop straw biochar (CSB) > livestock manure biochar (LMB) > sewage sludge biochar (SSB).
Over the past decades, various farming methods have evolved in response to the global challenges of increasing food demands, decreasing availability of arable land, and climate change. One of these ...new farming methods is vertical farming. To understand the contribution of vertical farms to future sustainable food production, beyond its efficient land-use and high yields, this paper evaluates the current carbon footprint of lettuce produced in an operational vertical farm in comparison to conventional open-field farming and both soil-based and hydroponic greenhouse cultivation in the Netherlands. The assessment includes the greenhouse gas emissions of the life cycle of the farm and the crop, from cradle-to-grave. An alternative scenario is explored to include the lost carbon sequestration potential by land-use change, identical packaging for all farming methods, and renewable energy usage. The carbon footprint of the vertical farm was 5.6–16.7 times greater than that of the conventional farming methods in the baseline scenario and 2.3 to 3.3 times in the alternative scenario. The electricity demands of the vertical farm represented 85% of the carbon footprint in the baseline scenario and 66% in the alternative scenario, suggesting that a significant reduction in electricity use is required to compete with conventional farming methods from a carbon footprint perspective. If this could be achieved, vertical farming could become a valid component of future sustainable and food secure systems by its efficient use of land, high yields, minimal use of water, nutrients, pesticides and herbicides, and the ability to be located within or adjacent to cities.
•Explores the potential for vertical farming (VF) as a sustainable food system.•Carbon footprint assessment of lettuce production in the Netherlands.•Compares a vertical farm to open-field farming and greenhouse horticulture.•The baseline carbon footprint of the vertical farm was 5.7–16.7 times greater.•Renewable energy greatly reduces the carbon footprint of the vertical farm.
Display omitted
•Climate change and human toxicity important in LCA of electrical traction machines.•Complete manufacturing range within 1.7–2.0 g CO2-eq./km for all studied motors.•Copper production ...is significant for toxicity impacts and effects on human health.•Design focus: energy efficiency, housings, end-windings, laminates and disassembly.
Ongoing development of electrified road vehicles entails a risk of conflict between resource issues and the reduction of greenhouse gas emissions. In this study, the environmental impact of the core design and magnet material for three electric vehicle traction motors was explored with life cycle assessment (LCA): two permanent magnet synchronous machines with neodymium-dysprosium-iron-boron or samarium-cobalt magnets, and a permanent magnet-assisted synchronous reluctance machine (PM-assisted SynRM) with strontium-ferrite magnets. These combinations of motor types and magnets, although highly relevant for vehicles, are new subjects for LCA. The study included substantial data compilation, machine design and drive-cycle calculations. All motors handle equal take-off, top speed, and driving conditions. The production (except of magnets) and use phases are modeled for two countries – Sweden and the USA – to exemplify the effects of different electricity supply. Impacts on climate change and human toxicity were found to be most important. Complete manufacturing range within 1.7–2.0 g CO2-eq./km for all options. The PM-assisted SynRM has the highest efficiency and lowest emissions of CO2. Copper production is significant for toxicity impacts and effects on human health, with problematic emissions from mining. Resource depletion results are divergent depending on evaluation method, but a sensitivity analysis proved other results to be robust. Key motor design targets are identified: high energy efficiency, slender housings, compact end-windings, segmented laminates to reduce production scrap, and easy disassembly.
PDF
