Estimation of environmental load of geotechnical structure using multiple regression analysis

Soil biotreatment effectiveness for reducing global warming potential from main polluting tillage operations in life cycle assessment phase

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.

Since most Green House Gases (GHGs) and air pollutants are generated from the same sources, it will be cost-effective to develop a GHGs reduction plan in combination with simultaneous removal of air pollutants. However, effects on air pollutants reduction according to implementing any GHG abatement plans have been rarely studied. Reflecting simultaneous removal of air pollutants along with the GHGs emission reduction, this study investigated relative cost effectiveness among GHGs reduction action plans in Busan Metropolitan City. We employed the Data Envelopment Analysis (DEA), a methodology that evaluates relative efficiency of decision-making units (DMUs) producing multiple outputs with multiple inputs, for the investigation. Assigning each GHGs reduction action plan to a DMU, implementation cost of each GHGs reduction action plan to an input, and reduction potential of GHGs and air pollutants by each GHGs reduction action plan to an output, we calculated efficiency scores for each GHGs reduction action plan. When the simultaneous removal of air pollutants with the GHGs reduction were considered, green house supply-insulation improvement and intelligent transportation system (ITS) projects had high efficiency scores for cost-positive action plans. For cost-negative action plans, green start network formation and running, and daily car use control program had high efficiency scores. When only the GHGs reduction was considered, project priority orders based on efficiency scores were somewhat different from those when both the removal of air pollutants and GHGs reduction were considered at the same time. The expected action plan priority difference is attributed to great difference of air pollutants reduction potential according to types of energy sources to be reduced.

Life-cycle-assessment of industrial scale biogas plants

Climate change and energy policies often encourage bioenergy as a sustainable greenhouse gas (GHG) reduction option. Recent research has raised concerns about the climate change impacts of bioenergy as heterogeneous pathways of producing and converting biomass, indirect impacts, uncertainties within the bioenergy supply chains and evaluation methods generate large variation in emission profiles. This research examines the combustion of wood pellets from forest residues to generate electricity and considers uncertainties related to GHG emissions arising at different points within the supply chain. Different supply chain pathways were investigated by using life cycle assessment (LCA) to analyse the emissions and sensitivity analysis was used to identify the most significant factors influencing the overall GHG balance. The calculations showed in the best case results in GHG reductions of 83% compared to coal-fired electricity generation. When parameters such as different drying fuels, storage emission, dry matter losses and feedstock market changes were included the bioenergy emission profiles showed strong variation with up to 73% higher GHG emissions compared to coal. The impact of methane emissions during storage has shown to be particularly significant regarding uncertainty and increases in emissions. Investigation and management of losses and emissions during storage is therefore key to ensuring significant GHG reductions from biomass.

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

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

The Home Appliance Recycling Law (hereunder referred to as the Law) for used cathode ray tube (CRT) TVs, air conditioners, refrigerators and washing machines was enacted in April 2001 in Japan. The Law requires that retailers reclaim, and manufacturers and importers recycle such home appliances. Consumers are required to pay collection and recycling fees incurred in disposing of any of the four home appliances. Home appliances must, as a general rule, be managed in accordance with the Law. In reality, other routes exist, such as via local authorities, scrap processors, illegal dumping and exporting. At about the time the Law was enacted, the refrigerant used for air conditioners and refrigerators was replaced by more environmentally friendly substances such as isobutene. Local authorities had the responsibility of disposing of the appliances of households before the enactment of the Law. It was general practice for local authorities to dispose of home appliances in landfills after breaking them up and recovering valuable resources such as iron, copper and aluminum. Although they made efforts to recover refrigerant fluorocarbons, there were not required to do so. This study analyzed the material flow resulting from the Law and other processing flows to quantify the global warming effect caused by home appliance recycling using the life cycle assessment (LCA) method. To evaluate the Law and to develop policy planning, the challenges of future efforts will be considered using time series data. For these reasons, we have assessed the Project Scenario, which corresponded to the present reality; the Baseline Scenario, which assumed that measures such as the Law were not implemented after 2000, and the Ideal Scenario, where all used products were recycled as prescribed by the Law. The environmental impacts for each scenario were estimated using value, which was obtained from multiplying the amount of reproduction and waste treatment by each inventory data. It is estimated that emission reductions of 4.7E+4 t CO2e, subtracted the Project Scenario from the Baseline Scenario, were reduced for TVs in 2001 through recycling. The impact from recycling glass from cathode ray tube (CRT) televisions is significant. An improvement of 2.3E+4 t CO2e could be anticipated by upgrading to the Ideal Scenario in 2001. It was estimated that there was a reduction of 9.2E+5 t CO2e in 2001 for air conditioners. Although the effect of the recovery for refrigerants contributed greatly, some fluorocarbons that are still discharged have had a considerable impact on greenhouse gas emissions. Hypothetically, a reduction of 3.2E+6 t CO2e could be anticipated with the Ideal Scenario in 2001. A reduction of 2.6E+6 t CO2e was achieved for refrigerators in 2001. Although a further reduction can be anticipated through the Ideal Scenario, there will not be much difference with the Project Scenario by 2010. It was estimated that 3.8E+4 t CO2e were reduced for washing machines in 2001. Only a small improvement can be expected through the Ideal Scenario. Since many assumptions were used in this study, a sensitivity analysis was carried out in order to grasp their impact. The findings of the sensitivity analysis are that the uncertainties are large, but the number of the greenhouse gas (GHG) reductions is still clear except for the difference between the Project Scenario and the Ideal Scenario for TVs. This analysis gives authenticity to the findings. Establishing a system for liquid crystal display and plasma display panel TVs is desirable because the absolute amount of used LCD/PDP TVs will rapidly increase as the usage of CRT TVs rapidly decreases from 2007. With regard to refrigerant recovery from air conditioners, a significant decrease in GHG emissions has been recorded. There is, however, still ample room for improvement. It will be necessary to switch to refrigerants with low global warming potentials (GWPs) or work more on improving the recovery rate in the future. Alternatives and recovery of fluorocarbons from refrigerators contributed greatly to GHG reductions. The GHG emissions from refrigerator recycling will be minimal whether used refrigerator will be processed legally or not because most used refrigerators will contain natural refrigerants in the near future. The improvement for washing machines was low because it was assumed that their main constituent steel has been previously recycled, and that the plastic recycling rate will not change significantly in the future. An improvement in the recycling technology itself is required. This study was carried out on four home appliance products, and it was found that the Home Appliance Recycling Law has brought significant reductions in GHG emissions. There is also room to make GHG reductions through improving the processing methods further. The impact on GHG emissions by fluorocarbons of air conditioners and refrigerators is the greatest. Adequate measures are particularly required for air conditioners that may continue to discharge GHGs in the future.

Feeding a growing, increasingly affluent population while limiting environmental pressures of food production is a central challenge for society. Understanding the location and magnitude of food production is key to addressing this challenge because pressures vary substantially across food production types. Applying data and models from life cycle assessment with the methodologies for mapping cumulative environmental impacts of human activities (hereafter cumulative impact mapping) provides a powerful approach to spatially map the cumulative environmental pressure of food production in a way that is consistent and comprehensive across food types. However, these methodologies have yet to be combined. By synthesizing life cycle assessment and cumulative impact mapping methodologies, we provide guidance for comprehensively and cumulatively mapping the environmental pressures (e.g., greenhouse gas emissions, spatial occupancy, and freshwater use) associated with food production systems. This spatial approach enables quantification of current and potential future environmental pressures, which is needed for decision makers to create more sustainable food policies and practices.

Life cycle assessment in support of sustainable transportation

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

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

Carbon emission oriented life cycle assessment and optimization strategy for meat supply chain

The carbon reduction potential of hydrogen in the low carbon transition of the iron and steel industry: The case of China

Background and objective: Carbon neutrality must be achieved across societal sectors through carbon neutral policies. Therefore, local governments, which realize the actual greenhouse gas (GHG) reduction, must develop GHG reduction strategies. This study aims to present information on the GHG reduction of the building sector (BS) at the local government level, for the carbon neutrality by 2050 (CN).Methods: The gross floor area (GFA) of all buildings and the total floor area of household (HBs), business (BBs), and public buildings (PBs) and by 2050 were predicted using building and demographic information from Jeollanam-do. Buildings were classified as over or under 10 years old. GHG emissions projection by 2050 were combined the GFA prediction results with public information on building energy consumption (BEC). After adjusting the nationwide CN goal for the BS in Jeollanam-do, the pathways for two scenarios were to estimate GHG reduction.Results: HBs showed the steepest increase in GFA, while BBs and PBs showed a very modest increase. About 30% of HBs and BBs were under 10 years and about 70% were over 10 years. The HB's GHG emissions increased remarkably, reflecting the GFA results, while the emissions of BBs and PBs didn't raised much. GHG reduction targets by 2030 were calculated as 1.4, 0.7, and 0.35 million TOE for HBs, BBs, and PBs, respectively. Reduction Scenario 1 shows a straight-line path with a negative slope from 2023. Reduction Scenario 2 shows an increase in emissions after 2023, which begins to decrease from 2028, falling with a curved steep slope until 2035, followed by a very modest decline until 2050.Conclusion: This study calculated GHG emissions from the BS by 2050 using the latest information on BEC and GHG calculation guidelines. The method in this study helps establish regional/local GHG reduction targets, setting scenarios, and estimating GHG reduction.