ＬＣＡ手法を用いた環境対応加工の環境負荷評価―環境対応旋削加工における二酸化炭素排出量―

One of the issues confronting manufacturers is the requirement for establishing sustainable production methods, which poise between economic feasibility and ecological preservation. Alternative sustainable cutting fluid methods must be developed since the traditional lubricants employed in machining operations are unsustainable from the environmental impact point of view. The balance between energy-production demand and quality-productivity is required for sustainable production. In this respect, this research studies the tool life, machining efficiency, energy consumption, and carbon emission under dry, flood machining, and minimum quantity lubrication machining. This study comprises two parts: evaluation of machining characteristics in terms of tool life, machining efficiency, energy consumption, and carbon emission, and the life cycle assessment (LCA) of inventories used during machining experimentation. The outcomes of this novel work revealed an increase of 42% and 61% in tool life at a cutting speed of 185 ​m/min under flood and MQL media than dry machining. At a cutting speed of 185 ​m/min in three different lubricating conditions, the percentage increase in the efficiency was 31%, and 28% for dry, flood, and MQL machining. In MQL machining, due to more uniform lubrication than flood machining, energy usage decreases by 38%, 32%, and 27% at the rate of metal removal of 93.67, 131.68, and 152.36 ​mm3/min. Also, A decrease in CO2 emissions of 16%, 21%, and 18% was attained in MQL machining than flood machining at 185, 215, and 245m/min cutting speeds. Furthermore, this also compares life cycle inventory analysis in dry, flood, and minimum quantity lubrication. Gate-to-gate approach methodology adopted for LCA analysis of system boundaries and functional unit to examine the environmental impression through ReCipe 2016, Endpoint (H) methodology. Sustainable assessment through life cycle analysis determined that dry and mist machining are more sustainable than wet machining.

The body of life cycle assessment (LCA) literature is vast and has grown over the last decade at a dauntingly rapid rate. Many LCAs have been published on the same or very similar technologies or products, in some cases leading to hundreds of publications. One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts. Despite the extensive available literature and policy need formore conclusive assessments, only modest attempts have been made to synthesize previous research. A significant challenge to doing so are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g., system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support. An emerging trend is meta-analysis of a set of results from LCAs, which has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results. Meta-analysis in this context is defined here as an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statisticalmore » sense (e.g., following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent. One example of the latter approach was published in Science by Farrell and colleagues (2006) clarifying the net energy and greenhouse gas (GHG) emissions of ethanol, in which adjustments included the addition of coproduct credit, the addition and subtraction of processes within the system boundary, and a reconciliation of differences in the definition of net energy metrics. Such adjustments therefore provide an even playing field on which all studies can be considered and at the same time specify the conditions of the playing field itself. Understanding the conditions under which a meta-analysis was conducted is important for proper interpretation of both the magnitude and variability in results. This special supplemental issue of the Journal of Industrial Ecology includes 12 high-quality metaanalyses and critical reviews of LCAs that advance understanding of the life cycle environmental impacts of different technologies, processes, products, and materials. Also published are three contributions on methodology and related discussions of the role of meta-analysis in LCA. The goal of this special supplemental issue is to contribute to the state of the science in LCA beyond the core practice of producing independent studies on specific products or technologies by highlighting the ability of meta-analysis of LCAs to advance understanding in areas of extensive existing literature. The inspiration for the issue came from a series of meta-analyses of life cycle GHG emissions from electricity generation technologies based on research from the LCA Harmonization Project of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy, which also provided financial support for this special supplemental issue. (See the editorial from this special supplemental issue [Lifset 2012], which introduces this supplemental issue and discusses the origins, funding, peer review, and other aspects.) The first article on reporting considerations for meta-analyses/critical reviews for LCA is from Heath and Mann (2012), who describe the methods used and experience gained in NREL's LCA Harmonization Project, which produced six of the studies in this special supplemental issue. Their harmonization approach adapts key features of systematic review to identify and screen published LCAs followed by a meta-analytical procedure to adjust published estimates to ones based on a consistent set of methods and assumptions to allow interstudy comparisons and conclusions to be made. In a second study on methods, Zumsteg and colleagues (2012) propose a checklist for a standardized technique to assist in conducting and reporting systematic reviews of LCAs, including meta-analysis, that is based on a framework used in evidence-based medicine. Widespread use of such a checklist would facilitate planning successful reviews, improve the ability to identify systematic reviews in literature searches, ease the ability to update content in future reviews, and allow more transparency of methods to ease peer review and more appropriately generalize findings. Finally, Zamagni and colleagues (2012) propose an approach, inspired by a meta-analysis, for categorizing main methodological topics, reconciling diverging methodological developments, and identifying future research directions in LCA. Their procedure involves the carrying out of a literature review on articles selected according to predefined criteria.« less

Who Cares About Life Cycle Assessment?

The global efforts to respond to climate change by reducing greenhouse gas were accelerated, as negative effects of climate change have been visualized and its direct damages to economy have been realized. Korea's Carbon Footprint Labeling get a lot of attention as one of the effective methods to contribute to national GHG reduction goal, and for enterprises to show customers how much effort the company put into global warming prevention. Consumers' interest on low-carbon products has been increasing. This study uses Life Cycle Assessment (LCA) method to calculate the amount of carbon emission of PET-bottled water, which reduced carbon emissions by using high efficiency manufacturing techniques. LCA Method is based on guidelines of Carbon Footprint Labeling, Korea government, and pre-manufacturing, manufacturing, and disposal steps are included while use step of the product is excluded from this method. In order to understand the effects of eco-design on carbon emissions, the PET-bottled water’s carbon emissions are compared before and after the change of manufacturing techniques. The result shows the improvement from 94.0 gCO2-eq/EA to 86.7 gCO2-eq/EA, and this means carbon emissions has been reduced by 8.4%, which is equivalent to 272tons of GHG emissions a year.

Greenhouse gas emissions induced by climate change have garnered global attention. Minimizing climate change can be achieved through the reduction of carbon emissions in transportation infrastructure construction and in the production of construction materials. This study aims to calculate carbon emissions in three hypothetical construction scenarios based on the life cycle assessment (LCA) method when a roadway passes across polluted soil at contaminated sites. Three methods are employed to remediate contaminated soil: off-site cement kiln co-processing, on-site ex-situ thermal desorption, and on-site ex-situ solidification/stabilization. Carbon emissions are calculated using the LCA method for each scenario. The baseline carbon emission is estimated for the scenario in which contaminated soil is remediated using the off-site cement kiln co-processing method, and the roadway subgrade is constructed using transported clean soil. In the other two scenarios, contaminated soils are remediated using the on-site ex-situ thermal desorption and solidification/stabilization methods, respectively, and then they are reused as roadway subgrade materials. The LCA analyses demonstrate that the total carbon emission reductions range from 1168.48 to 2379.62 tons per basic unit, corresponding to decreased of 19.31% to 39.33%, respectively, compared to baseline. The reuse of solid waste to replace sand and ordinary Portland cement (OPC) as raw materials in roadway construction reduces carbon emissions by 498.98 tons. Finally, a comparison of carbon emissions between the three scenarios indicates that reducing carbon emissions in the remediation of contaminated soil and reusing solid waste as construction materials are two important methods for achieving overall carbon emission reductions in roadway construction projects.

Experimental investigation and sustainability assessment to evaluate environmentally clean machining of 15-5 PH stainless steel

Despite the ever-growing body of life cycle assessment (LCA) literature on electricity generation technologies, inconsistent methods and assumptions hamper comparison across studies and pooling of published results. Synthesis of the body of previous research is necessary to generate robust results to assess and compare environmental performance of different energy technologies for the benefit of policy makers, managers, investors, and citizens. With funding from the U.S. Department of Energy, the National Renewable Energy Laboratory initiated the LCA Harmonization Project in an effort to rigorously leverage the numerous individual studies to develop collective insights. The goals of this project were to: (1) understand the range of published results of LCAs of electricity generation technologies, (2) reduce the variability in published results that stem from inconsistent methods and assumptions, and (3) clarify the central tendency of published estimates to make the collective results of LCAs available to decision makers in the near term. The LCA Harmonization Project's initial focus was evaluating life cycle greenhouse gas (GHG) emissions from electricity generation technologies. Six articles from this first phase of the project are presented in a special supplemental issue of the Journal of Industrial Ecology on Meta-Analysis of LCA: coal (Whitaker et al. 2012), concentratingmore » solar power (Burkhardt et al. 2012), crystalline silicon photovoltaics (PVs) (Hsu et al. 2012), thin-film PVs (Kim et al. 2012), nuclear (Warner and Heath 2012), and wind (Dolan and Heath 2012). Harmonization is a meta-analytical approach that addresses inconsistency in methods and assumptions of previously published life cycle impact estimates. It has been applied in a rigorous manner to estimates of life cycle GHG emissions from many categories of electricity generation technologies in articles that appear in this special supplemental supplemental issue, reducing the variability and clarifying the central tendency of those estimates in ways useful for decision makers and analysts. Each article took a slightly different approach, demonstrating the flexibility of the harmonization approach. Each article also discusses limitations of the current research, and the state of knowledge and of harmonization, pointing toward a path of extending and improving the meta-analysis of LCAs.« less

An Inconvenient Truth-Global Warming on Greenhouse Gas (GHG) Reduction under Kyoto Protocol Regime to Post Kyoto Protocol in ASIA

The electric power industry is one of the major industries in terms of carbon dioxide (CO2) emissions, and it is necessary to explore low-carbon green power generation models. In recent years, more research has focused on the difference in carbon emissions in fossil energy versus renewable energy but ignored the impact of energy on human well-being. The life cycle assessment (LCA) method is a better method for assessing the impact of the low-carbon model on human well-being. In this paper, the carbon footprints of coal power plants and photovoltaic power (PV) plants generating 1 Kilowatt hour (kWh) of electricity are compared to analyze the degree of carbon emissions at different stages of the two models, and the environmental impact potential of the two models is analyzed using the LCA method. The differences between the two models in terms of human well-being were analyzed through questionnaires and quantified using the hierarchical analysis method. The impact of the different models on human well-being was compared using LCA method. The results of the study were as follows: the total CO2 emissions from coal-fired power generation at the 1 kWh standard were 973.38 g, while the total CO2 emissions from PV power generation were 91.95 g, and the carbon emission intensity of coal-fired power plants was higher than that of PV power plants. The global warming potential and eutrophication potential of coal-fired power plants were higher than those of PV power plants, and the rest of the indicators were lower than those of PV power plants. The composite human well-being index of PV power plants was 0.613 higher than that of coal-fired power plants at 0.561. The per capita income–global warming potential of PV power plants was higher than that of coal-fired power plants, indicating that PV power plants were a low carbon-emission and high well-being model. In conclusion, the PV power plant model is a low-carbon and high human well-being industrial model that is worthy of application in the Qilian Mountains region. The low-carbon industrial model proposed in this study can have a positive effect on regional ecological environmental protection and human well-being enhancement.

Interrogating greenhouse gas emissions of different dietary structures by using a new food equivalent incorporated in life cycle assessment method

Circular utilization of urban tree waste contributes to the mitigation of climate change and eutrophication

The shield method is a commonly used construction technique in subway tunnel engineering. However, studies on greenhouse gas (GHG) emissions specifically in subway shield tunnel engineering are lacking. This study aims to investigate the GHG emission characteristics and GHG reduction pathways during the construction period of subway shield tunnels. Firstly, based on the life cycle assessment (LCA) method, a greenhouse gas (GHG) emission quantification model for the shield tunnel construction period was developed using a multi-level decomposition of construction. Then, the GHG emission level and intensity during the construction period of a case project are quantified, and its emission characteristics and GHG reduction potential points are assessed. Finally, a comprehensive path for GHG reduction in subway shield tunnel engineering is proposed. The research results indicate that constructing 1 km of subway shield tunnel can generate 19,294.28 t CO2eq. Among these, material production element dominates the emissions with a percentage of 89.05%, while transportation and mechanical construction elements contribute 1.81% and 9.14%, respectively. From the structure perspective, the main structure contributes 88.73% of total emissions, while the ancillary structure contributes 11.27%. Among them, the working shaft and tunnel segments are the main sources of emissions for the main structure, accounting for 23.65% and 65.08%, respectively. Connecting channel and end reinforcement are the main emission sources of the ancillary structures, accounting for 43.63% and 31.30%, respectively. These findings provide a scientific foundation for the environmentally friendly transformation of urban railway development regarding pursuing "carbon peaking and carbon neutrality" strategic goals.

Recently, the IMO has completed the guidelines on the life cycle greenhouse gas intensity of marine fuels to accelerate the application of alternative fuels. Low-carbon fuels may persist for decades and have become a key transitional phase in replacing marine fuels. A more comprehensive methodology for evaluating the carbon emission levels of marine fuels was explored, and the carbon emissions and environmental impacts of a 150,000-ton shuttle tanker under 19 dual-fuel power scenarios were evaluated using the Energy Efficiency Design Index (EEDI) and life cycle assessment (LCA) method. The results show that liquefied natural gas (LNG) has a higher carbon control potential level compared to liquefied petroleum gas (LPG) and methanol (MeOH), while LPG is superior to MeOH based on EEDI evaluation. LCA analysis results show that MeOH (biomass) has the best carbon control potential considering the carbon emissions of the well-to-tank phase of the fuel, followed by LNG, LPG, MeOH (natural gas, NG), and MeOH (coal). However, MeOH (NG) and MeOH (coal) had greater negative environmental impacts. This study provides method support and a direction toward improvement for revising related technical specifications and regulations for dual-fuel vessel performance evaluation, considering the limitations of various maritime regulations.

Evaluation of the effect of accounting method, IPCC v. LCA, on grass-based and confinement dairy systems’ greenhouse gas emissions

The use of rail transits results in the generation of a large amount of carbon emissions. Throughout the life cycle of a rail transit system, huge amounts of carbon are emitted, which contributes to the threat posed by carbon emission on the city ecosystem. Despite the many methods previously proposed to quantify carbon emissions from rail transit systems, a method that can be applied to measure carbon emissions of monorail systems is yet to be developed. We have used the life cycle assessment (LCA) method to propose a method that can be used to quantify carbon emissions from monorail transits. The life cycle of a monorail transit system was divided into four stages (production, construction, use, and end-of-life). A monorail transit line segment in Chongqing, China, was selected for a case study. The results show that the “use” stage of the monorail transit line system significantly increases (93.2%) carbon emissions, while the “end-of-life” stage does not contribute significantly to the total carbon emitted. The processes of generation of steal, concrete, and cement are the three leading processes that contribute to the emission of carbon dioxide. The percentages of carbon emitted during these processes are 32%, 29.6%, and 13.3%, respectively. Prestressed concrete activity accounts for the largest proportion (91.1%) of the total carbon emissions. The results presented herein can potentially help in realizing sustainable development and developing green transportation.