Life Cycle Assessment of a Lithium‐Ion Battery Vehicle Pack

Electric vehicles (EVs) have no tailpipe emissions, but the production of their batteries leads to environmental burdens. In order to avoid problem shifting, a life cycle perspective should be applied in the environmental assessment of traction batteries. The aim of this study was to provide a transparent inventory for a lithium‐ion nickel‐cobalt‐manganese traction battery based on primary data and to report its cradle‐to‐gate impacts. The study was carried out as a process‐based attributional life cycle assessment. The environmental impacts were analyzed using midpoint indicators. The global warming potential of the 26.6 kilowatt‐hour (kWh), 253‐kilogram battery pack was found to be 4.6 tonnes of carbon dioxide equivalents. Regardless of impact category, the production impacts of the battery were caused mainly by the production chains of battery cell manufacture, positive electrode paste, and negative current collector. The robustness of the study was tested through sensitivity analysis, and results were compared with preceding studies. Sensitivity analysis indicated that the most effective approach to reducing climate change emissions would be to produce the battery cells with electricity from a cleaner energy mix. On a per‐kWh basis, cradle‐to‐gate greenhouse gas emissions of the battery were within the range of those reported in preceding studies. Contribution and structural path analysis allowed for identification of the most impact‐intensive processes and value chains. This article provides an inventory based mainly on primary data, which can easily be adapted to subsequent EV studies, and offers an improved understanding of environmental burdens pertaining to lithium‐ion traction batteries.     

Life cycle assessment of emerging environmental technologies in the early stage of development: A case study on nanostructured materials

The use of nanostructured materials has been recently proposed in the field of environmental nanoremediation. This approach consists in using nanomaterials not directly, but as building blocks for the design of nano‐porous micro‐dimensional systems, overcoming the eco‐ and health‐toxicology risks generally associated with the use of nano‐sized technologies. Herein we report the use of life cycle assessment (LCA) as an eco‐design tool for optimizing the production of cellulose nanosponges (CNS), nanostructured materials recently developed for water remediation purposes. LCA was applied from the acquisition of raw materials to the synthesis of CNS (from cradle‐to‐gate), considering three production systems, from the lab‐level to a modeled scale‐up system. The lab‐scale LCA identified the main environmental hotspots, namely the energy‐consuming steps and the final purification of the material (washing step). In a second lab‐scale production, an improvement action could be implemented, switching the washing solvent from methanol to water and decreasing the washing temperature. A second LCA showed a reduced contribution to the impacts from the materials, while the global impacts remained within the same order of magnitude. A simulated scale‐up of the process allowed to optimize the energy‐consuming steps and the water consumption, through internal recycling. A third LCA assessed the resulting benefits and a decrease in the global impacts by two orders of magnitude. Our study contributes to the discussion of LCA community, providing a focus on the importance of scaling‐up of emerging technologies, namely nanostructured porous materials, highlighting the benefits of a LCA based approach since the very beginning of product design (eco‐design).     

Energy requirements and environmental impacts associated with the production of short rotation willow (Salix sp.) chip in Ireland

Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source of biomass to contribute to renewable energy goals. The aim of this study is to evaluate the energy requirements and environmental impacts associated with willow (Salix sp.) cultivation, harvest, and transport using life cycle assessment (LCA). In this study, only emissions from the production of the willow chip are included, end‐use emissions from combustion are not considered. In this LCA study, three impact categories are considered; acidification potential, eutrophication potential and global warming potential. In addition, the cumulative energy demand and energy ratio of the system are evaluated. The results identify three key processes in the production chain which contribute most to all impact categories considered; maintenance, harvest and transportation of the crop. Sensitivity analysis on the type of fertilizers used, harvesting technologies and transport distances highlights the effects of these management techniques on overall system performance. Replacement of synthetic fertilizer with biosolids results in a reduction in overall energy demand, but raises acidification potential, eutrophication potential and global warming potential. Rod harvesting compares unfavourably in comparison with direct chip harvesting in each of the impact categories considered due to the additional chipping step required. The results show that dedicated truck transport is preferable to tractor‐trailer transport in terms of energy demand and environmental impacts. Finally, willow chip production compares favourably with coal provision in terms of energy ratio and global warming potential, while achieving a higher energy ratio than peat provision but also a higher global warming potential.     

The Role of Scale and Technology Maturity in Life Cycle Assessment of Emerging Technologies: A Case Study on Carbon Nanotubes

Life cycle assessment (LCA) has been applied for assessing emerging technologies, where large‐scale production data are generally lacking. This study introduces a standardized scheme for technology and manufacturing readiness levels to contextualize a technology's development stage. We applied the scheme to a carbon nanotube (CNT) LCA and found that, regardless of synthesis technique, CNT manufacturing will become less energy intensive with increased levels of readiness. We examined the influence of production volume on LCA results using primary data from a commercial CNT manufacturer with approximately 100 grams per day production volume and engineering design of a scaled‐up process with 1 tonne per day production capacity. The results show that scaling up could reduce 84% to 94% of its cradle‐to‐gate impacts, mainly as a result of the recycling of feedstock that becomes economically viable only beyond certain minimum production volume. This study shows that LCAs on emerging technologies based on immature data should be interpreted in conjunction with their technology and manufacturing readiness levels and reinforces the need of standardizing and communicating information on these readiness levels and scale of production in life cycle inventory practices.     

EU‐Average Impacts of Wheat Production: A Meta‐Analysis of Life Cycle Assessments

Wheat is an important commodity in Europe. With a production of 133 million tonnes per year and annual import and export accounting for 6.3 and 5.3 billion US$, respectively, wheat is the most important cereal in Europe. Wheat cultivation further feeds into a wide variety of products ranging from bread, over imitation meat, to biofuels and bio‐based materials. Therefore, it is desirable to have a synthetic life cycle assessment (LCA) of the impacts of an average kilogram (kg) of wheat produced in Europe. This article aims to provide such a synthesis using two strategies. In the first strategy, we give an overview of published LCA impacts of wheat production. A second strategy is a meta‐analysis in which a re‐evaluation is made of 20 available life cycle inventories representing cases in 11 different European countries. Based on the production shares of these countries in the total European production, weighted average impacts are calculated. These weighted averages of the re‐evaluated inventories show that an average kg of wheat grain produced in Europe demands 3.25 megajoules of nonrenewable, fossil energy, emits 0.61 to 0.65 kg carbon dioxide equivalents, triggers terrestrial acidification of 4.94 to 6.51 grams (g) sulphur dioxide equivalents, freshwater eutrophication of 0.08 to 0.09 g phosphorous equivalents, marine eutrophication of 4.97 to 7.60 g nitrogen equivalents, and occupies 1.63 square meter years of agricultural land. The re‐evaluation of studies results in similar impacts as the mere reviewing of energy demands and global warming potentials. Given the many applications of wheat, the presented meta‐analysis is interesting to evaluate the average and range of environmental performance of wheat production in Europe, but is also useful as an input in assessing impacts of wheat‐based products.     

Uncertainty Quantification in Life Cycle Assessments: Interindividual Variability and Sensitivity Analysis in LCA of Air‐Conditioning Systems

The life cycle environmental profile of energy‐consuming products, such as air conditioning, is dominated by the products’ use phase. Different user behavior patterns can therefore yield large differences in the results of a cradle‐to‐grave assessment. Although this variation and uncertainty is increasingly recognized, it remains often poorly characterized in life cycle assessment (LCA) studies. Today, pervasive sensing presents the opportunity to collect rich data sets and improve profiling of use‐phase parameters, in turn facilitating quantification and reduction of this uncertainty in LCA. This study examined the case of energy use in building cooling systems, focusing on global warming potential (GWP) as the impact category. In Singapore, building cooling systems or air conditioning consumes up to 37% of national electricity demand. Lack of consideration of variation in use‐phase interaction leads to the oversized designs, wasted energy, and therefore reducible GWP. Using a high‐resolution data set derived from sensor observations, energy use and behavior patterns of single‐office occupants were characterized by probabilistic distributions. The interindividual variability and use‐phase variables were propagated in a stochastic model for the life cycle of air‐conditioning systems and simulated by way of Monte Carlo analysis. Analysis of the generated uncertainties identified plausible reductions in global warming impact through modifying user interaction. Designers concerned about the environmental profile of their products or systems need better representation of the underlying variability in use‐phase data to evaluate the impact. This study suggests that data can be reliably provided and incorporated into the life cycle by proliferation of pervasive sensing, which can only continue to benefit future LCA.     

Combining Material Flow Analysis,Life Cycle Assessment,and Multiattribute Utility Theory

Three assessment methods, material flow analysis (MFA), life cycle analysis (LCA), and multiattribute utility theory (MAUT) are systematically combined for supporting the choice of best end‐of‐life scenarios for polyethylene terephthalate (PET) waste in a municipality of a developing country. MFA analyzes the material and energy balance of a firm, a region, or a nation, identifying the most relevant processes; LCA evaluates multiple environmental impacts of a product or a service from cradle to grave; and MAUT allows for inclusion of other aspects along with the ecological ones in the assessment. We first systematically coupled MFA and LCA by defining “the service offered by the total PET used during one year in the region” as the functional unit. Inventory and impacts were calculated by multiplying MFA flows with LCA impacts per kilogram. We used MAUT to include social and economic aspects in the assessment. To integrate the subjective point of view of stakeholders in the MAUT, we normalized the environmental, social, and economic variables with respect to the magnitude of overall impacts or benefits in the country. The results show large benefits for recycling scenarios from all points of view and also provide information about waste treatment optimization. The combination of the three assessment methods offers a powerful integrative assessment of impacts and benefits. Further research should focus on data collection methods to easily determine relevant material flows. LCA impact factors specific to Colombia should be developed, as well as more reliable social indicators.     

Including albedo in time‐dependent LCA of bioenergy

Albedo change during feedstock production can substantially alter the life cycle climate impact of bioenergy. Life cycle assessment (LCA) studies have compared the effects of albedo and greenhouse gases (GHGs) based on global warming potential (GWP). However, using GWP leads to unequal weighting of climate forcers that act on different timescales. In this study, albedo was included in the time‐dependent LCA, which accounts for the timing of emissions and their impacts. We employed field‐measured albedo and life cycle emissions data along with time‐dependent models of radiative transfer, biogenic carbon fluxes and nitrous oxide emissions from soil. Climate impacts were expressed as global mean surface temperature change over time (?T) and as GWP. The bioenergy system analysed was heat and power production from short‐rotation willow grown on former fallow land in Sweden. We found a net cooling effect in terms of ?T per hectare (?3.8 × 10^–11 K in year 100) and GWP₁₀₀ per MJ fuel (?12.2 g CO₂e), as a result of soil carbon sequestration via high inputs of carbon from willow roots and litter. Albedo was higher under willow than fallow, contributing to the cooling effect and accounting for 34% of GWP₁₀₀, 36% of ?T in year 50 and 6% of ?T in year 100. Albedo dominated the short‐term temperature response (10–20 years) but became, in relative terms, less important over time, owing to accumulation of soil carbon under sustained production and the longer perturbation lifetime of GHGs. The timing of impacts was explicit with ?T, which improves the relevance of LCA results to climate targets. Our method can be used to quantify the first‐order radiative effect of albedo change on the global climate and relate it to the climate impact of GHG emissions in LCA of bioenergy, alternative energy sources or land uses.     

Environmental Implications and Costs of Municipal Solid Waste‐Derived Ethylene

Carbon recycling, in which organic waste is recycled into chemical feedstock for material production, may provide benefits in resource efficiency and a more cyclical economy—but may also create “trade‐offs” in increased impacts elsewhere. We investigate the system‐wide environmental burdens and cost associated with carbon recycling routes capable of converting municipal solid waste (MSW) by gasification and Fischer‐Tropsch synthesis into ethylene. Results are compared to business‐as‐usual (BAU) cases in which ethylene is derived from fossil resources and waste is either landfilled with methane and energy recovery (BAU#1) or incinerated (BAU#2) with energy recovery. Monte Carlo and sensitivity analysis is used to assess uncertainties of the results. Results indicate that carbon recycling may lead to a reduction in cumulative energy demand (CED), total material requirement (TMR), and acidification, when compared to BAU#1. Global warming potential is found to be similar or slightly lower than BAU#1 and BAU#2. In comparison to BAU#2, carbon recycling results in higher CED, TMR, acidification, and smog potential, mainly as a result of larger (fossil‐based) energy offsets from energy recovery. However, if a renewable power mix (envisioned for the future) is assumed to be offset, BAU#2 impacts may be similar or higher than carbon recycling routes. Production cost per kilogram (kg) MSW‐derived ethylene range between US$1.85 and US$2.06 (Jan 2011 US$). This compares to US$1.17 per kg for fossil‐based ethylene. Waste‐derived ethylene breaks even with its fossil‐based counterpart at a tipping fee of roughly US$42 per metric ton of waste feedstock.     

Life Cycle Assessment of Diesel and Electric Public Transportation Buses

The Clean Air Act in the United States identifies diesel‐powered motor vehicles, including transit buses, as significant sources of several criteria pollutants that contribute to ground‐level ozone formation or smog. The effects of air pollution in urban areas are often more significant due to congestion and can lead to respiratory and cardiovascular health impacts. Life cycle assessment (LCA) has been utilized in the literature to compare conventional gasoline‐powered passenger cars with various types of electric and hybrid‐powered alternatives, however, no similarly detailed studies exist for mass transit buses. LCA results from this study indicate that the use phase, consisting of diesel production/combustion for the conventional bus and electricity generation for the electric bus, dominates most impact categories; however, the effects of battery production are significant for global warming, carcinogens, ozone depletion, and eco‐toxicity. There is a clear connection between the mix of power‐generation technologies and the preference for the diesel or electric bus. With the existing U.S. average grid, there is a strong preference for the conventional diesel bus over the electric bus when considering global warming impacts alone. Policy makers must consider regional variations in the electricity grid prior to recommending the use of battery electric buses to reduce carbon dioxide (CO₂) emissions. This study found that the electric bus was preferable in only eight states, including Washington and Oregon. Improvements in battery technology reduce the life cycle impacts from the electric bus, but the electricity grid makeup is the dominant variable.     

A Methodical Approach for Systematic Life Cycle Assessment of Wood‐Based Furniture

Existing life cycle assessment (LCA) studies for furniture focus on single pieces of furniture and use a bottom‐up approach based on their bill of materials (BOM) to build up the data inventories. This approach does not ensure completeness regarding material and energy fluxes and representativeness regarding the product portfolio. Integrating material and energy fluxes collected at company level into product LCA (top‐down approach) over‐rides this drawback. This article presents a method for systematic LCA of industrially produced furniture that merges the top‐down approach and bottom‐up approach. The developed method assigns data collected at the company level to the different products while, at the same time, considering that wood‐based furniture is a complex product. Hence, several classifications to reduce the complexity to a manageable level have been developed. Simultaneously, a systematic calculation routine was established. The practical implementation of the developed method for systematic LCA is carried out in a case study within the German furniture industry. The system boundary was set in accord with the EN 15804 specification cradle‐to‐gate‐with‐options. The analysis therefore includes the manufacturing phase supplemented by an end‐of‐life scenario. The case study shows that the manufacturing of semifinished products (especially wood‐based panels and metal components) as well as the electric energy demand in furniture manufacturing account for a notable share of the environmental impacts. A sensitivity analysis indicates that up to roughly 10% of the greenhouse gas emissions are not recorded when conducting an LCA based on a BOM instead of applying the developed approach.     

Assessing biodiversity loss due to land use with Life Cycle Assessment: are we there yet?

Ecosystems are under increasing pressure from human activities, with land use and land‐use change at the forefront of the drivers that provoke global and regional biodiversity loss. The first step in addressing the challenge of how to reverse the negative outlook for the coming years starts with measuring environmental loss rates and assigning responsibilities. Pinpointing the global pressures on biodiversity is a task best addressed using holistic models such as Life Cycle Assessment (LCA). LCA is the leading method for calculating cradle‐to‐grave environmental impacts of products and services; it is actively promoted by many public policies, and integrated as part of environmental information systems within private companies. LCA already deals with the potential biodiversity impacts of land use, but there are significant obstacles to overcome before its models grasp the full reach of the phenomena involved. In this review, we discuss some pressing issues that need to be addressed. LCA mainly introduces biodiversity as an endpoint category modeled as a loss in species richness due to the conversion and use of land over time and space. The functional and population effects on biodiversity are mostly absent due to the emphasis on species accumulation with limited geographic and taxonomical reach. Current land‐use modeling activities that use biodiversity indicators tend to oversimplify the real dynamics and complexity of the interactions of species among each other and with their habitats. To identify the main areas for improvement, we systematically reviewed LCA studies on land use that had findings related to global change and conservation ecology. We provide suggestion as to how to address some of the issues raised. Our overall objective was to encourage companies to monitor and take concrete steps to address the impacts of land use on biodiversity on a broader geographical scale and along increasingly globalized supply chains.     

Steel‐versus‐Concrete Debate Revisited: Global Warming Potential and Embodied Energy Analyses based on Attributional and Consequential Life Cycle Perspectives

In the study of sustainable building materials, the comparison of the life cycle environmental performance of steel and reinforced concrete has been a popular and important topic. Based in Singapore, this is one of the first studies in the literature that applies both attributional and consequential life cycle approaches to compare the global warming potential and embodied energies of these two materials, which are widely used for the structural parts of buildings. It was found that 1 kilogram (kg) of steel can be replaced by 1 or 4.25 kg of reinforced concrete. Two consequential scenarios for each of three combinations of primary and secondary steel were assessed. It was found that reinforced concrete produces less carbon dioxide emissions and incurs less embodied energy in most of these cases, but when different sustainable primary steel‐making technologies were incorporated, these results may be reversed. We applied consequential life cycle assessment and scenario analysis to describe how changes in the demand for structural steel and reinforced concrete in Singapore's building industry give rise to different environmental impacts. Specifically, the consequential life cycle approach revealed that, over the short term, the impact of substituting steel with reinforced concrete depends on the difference in impacts resulting from the transportation of these two materials within Singapore. Based on these lessons, integrated technology policies to improve the overall sustainability of using steel for construction were proposed.     

Life Cycle Assessment of Biomass‐based Combined Heat and Power Plants

Norway, like many countries, has realized the need to extensively plan its renewable energy future sooner rather than later. Combined heat and power (CHP) through gasification of forest residues is one technology that is expected to aid Norway in achieving a desired doubling of bioenergy production by 2020. To assess the environmental impacts to determine the most suitable CHP size, we performed a unit process‐based attributional life cycle assessment (LCA), in which we compared three scales of CHP over ten environmental impact categories—micro (0.1 megawatts electricity [MWe]), small (1 MWe), and medium (50 MWe) scale. The functional units used were 1 megajoule (MJ) of electricity and 1 MJ of district heating delivered to the end user (two functional units), and therefore, the environmental impacts from distribution of electricity and hot water to the consumer were also considered. This study focuses on a regional perspective situated in middle‐Norway's Nord‐ and Sør‐Trøndelag counties. Overall, the unit‐based environmental impacts between the scales of CHP were quite mixed and within the same magnitude. The results indicated that energy distribution from CHP plant to end user creates from less than 1% to nearly 90% of the total system impacts, depending on impact category and energy product. Also, an optimal small‐scale CHP plant may be the best environmental option. The CHP systems had a global warming potential ranging from 2.4 to 2.8 grams of carbon dioxide equivalent per megajoule of thermal (g CO₂‐eq/MJ_th) district heating and from 8.8 to 10.5 grams carbon dioxide equivalent per megajoule of electricity (g CO₂‐eq/MJ_el) to the end user.     

Recent Progress in Flexible Electrochemical Capacitors: Electrode Materials,Device Configuration,and Functions

With increasing demand for portable, flexible, and even wearable electronic devices, flexible energy storage systems have received increasing attention as a key component in this emerging field. Among the options, supercapacitors, commonly referred to as ultracapacitors or electrochemical capacitors, are widely recognized as a potential energy storage system due to their high power, fast charge/discharge rate, long cycling life‐time, and low cost. To date, considerable effort has been dedicated to developing high‐performance flexible supercapacitors based on various electrode materials; including carbon nanomaterials (e.g., carbon nanotubes, graphene, porous carbon materials, carbon paper, and textile), conducting polymers (e.g., polyaniline, polypyrrole, polythiophene), and hybrid materials. A brief introduction to the field is provided and the state‐of‐the‐art is reviewed with special emphasis on electrode materials and device configurations.     

Climate impact assessment of willow energy from a landscape perspective: a Swedish case study

Locally produced bioenergy can decrease the dependency on imported fossil fuels in a region, while also being valuable for climate change mitigation. Short‐rotation coppice willow is a potentially high‐yielding energy crop that can be grown to supply a local energy facility. This study assessed the energy performance and climate impacts when establishing willow on current fallow land in a Swedish region with the purpose of supplying a bio‐based combined heat and power plant. Time‐dependent life cycle assessment (LCA) was combined with geographic information system (GIS) mapping to include spatial variation in terms of transport distance, initial soil organic carbon content, soil texture and yield. Two climate metrics were used [global warming potential (GWP) and absolute global temperature change potential (AGTP)], and the energy performance was determined by calculating the energy ratio (energy produced per unit of energy used). The results showed that when current fallow land in a Swedish region was used for willow energy, an average energy ratio of 30 MJ MJ^?1 (including heat, power and flue gas condensation) was obtained and on average 84.3 Mg carbon per ha was sequestered in the soil during a 100‐year time frame (compared with the reference land use). The processes contributing most to the energy use during one willow rotation were the production and application of fertilizers (~40%), followed by harvest (~35%) and transport (~20%). The temperature response after 100 years of willow cultivation was ?6·10^?16 K MJ^?1 heat, which is much lower compared with fossil coal and natural gas (70·10^?16 K MJ^?1 heat and 35·10^?16 K MJ^?1 heat, respectively). The combined GIS and time‐dependent LCA approach developed here can be a useful tool in systematic analysis of bioenergy production systems and related land use effects.     

可持续消费的内涵及研究进展——产业生态学视角

生产和消费是产生诸多环境问题的根本原因,而可持续生产和消费则是实现可持续发展的根本途径。基于产业生态学视角,界定了可持续消费的定义及内涵,认为可持续消费首先须符合代内公平、代际公平和资源能源永续合理利用等可持续理念;其次辨识了可持续消费研究依次经历关注消费者行为直接环境影响、关注产品和服务生命周期环境影响到关注消费者责任3个阶段;最后结合我国城市化、工业化背景,提出我国可持续消费研究应该以城市居民为重点、加强生命周期数据库建设和内注重可持续生产等建议。     

Time Horizon and Dominance in Dynamic Life Cycle Assessment

Temporal aspects have traditionally not been recognized adequately in life cycle assessment (LCA). The dynamic LCA model recently proposed offers a significant step forward in the dynamic assessment of global warming impacts. The results obtained with dynamic LCA are highly sensitive to the choice of a time horizon. Therefore, decision making between alternative systems can be critical because conclusions are dependent on the specific time horizon. In this article, we develop a decision‐making methodology based on the concept of time dominance. We introduce instantaneous and cumulative time dominance criteria to the dynamic LCA context and argue why the dominance of an alternative should also imply preference. Our approach allows for the rejection of certain alternatives without the determination of a specific time horizon. The number of decision‐relevant alternatives can thereby be reduced and the decision problem facilitated. We demonstrate our methodology by means of a case study of end‐of‐life alternatives for a wooden chair derived from the original authors of dynamic LCA and discuss the implications and limitations of the approach. The methodology based on time dominance criteria is supplementary to the dynamic LCA model, but does not substitute it. The overall value of this article stretches beyond LCA onto more general assessments of global warming, for example, in policy where the choice of a time horizon is equally significant.