Purpose
The objective of this case study is to identify the relevant processes needed in the environmental assessment of the end of life of a building and to identify the demolition process variables that significantly affect energy consumption and emissions of greenhouse gases. Different scenarios of demolition, based on three alternatives for managing construction and demolition waste (C&DW) generated during demolition works, are analyzed. This study is based upon typical construction and demolition practices and waste management in Spain.Methods
Life cycle assessment (LCA) methodology is applied to assess objectively and quantitatively different C&DW management plans during the design phase and to identify the significant environmental aspects. The impact categories considered are global warming potential and human toxicity potential. Furthermore, the indicator primary energy (non renewable energy from fossil fuels) is also studied.Results
Design of C&DW management plans to enhance the recovery of waste, reducing significantly the selected environmental indicators, was assessed in this study. Waste transport from the demolition work to the treatment plant and the transport of the non-recyclable fraction to the final disposal, as well as the fuel consumption in hydraulic demolition equipment and in the loading/unloading equipment of the treatment plants, are the most significant environmental aspects associated with the management plan based on a selective demolition, whereas in a conventional demolition process, the main environmental aspect is waste transport from the demolition work to final disposal.Conclusions
LCA studies allow an assessment of different demolition processes. A tool for recording environmental data has been developed. This tool provides in a systematic manner life cycle inventory and life cycle impact assessment of the end of life of a building, facilitating the study of management plans in the design phase. 相似文献Introduction
The amount of waste generated in Europe and, beyond, by our production and consumption patterns is significant. A proper waste management is essential in order to reduce detrimental environmental impacts. For the European Union, the general principles of good waste management are outlined in the Waste Framework Directive (2008/98/EC). This directive establishes a five-step hierarchy of waste management starting with the preferred option of waste prevention followed by preparing waste for reuse, recycling and other recovery with disposal (such as landfill) as the last resort. 相似文献Purpose
Construction and demolition (C&D) waste recycling has been considered to be a valuable option not only for minimising C&D waste streams to landfills but also for mitigating primary mineral resource depletion. However, the potentially higher cement demand due to the larger surface of the coarse recycled aggregates challenges the environmental benefits of recycling concrete. Furthermore, it is unclear how the environmental impacts depend on concrete mixture, cement type, aggregates composition and transport distances.Methods
We therefore analysed the life cycle impacts of 12 recycled concrete (RC) mixtures with two different cement types and compared it with corresponding conventional concretes (CC) for three structural applications. The RC mixtures were selected according to laws, standards and construction practice in Switzerland. We compared the environmental impacts of ready-for-use concrete on the construction site, assuming equal lifetimes for recycled and conventional concrete in a full life cycle assessment. System expansion and substitution are considered to achieve the same functionality for all systems.Results and discussion
The results show clear (～30 %) environmental benefits for all RC options at endpoint level (ecoindicator 99 and ecological scarcity). The difference is mainly due to the avoided burdens associated to reinforcing steel recycling and avoided disposal of C&D waste. Regarding global warming potential (GWP), the results are more balanced and primarily depend on the additional amount of cement needed for RC. Above 22 to 40 kg additional cement per cubic metre of concrete, RC exhibits a GWP comparable to CC. Additional transport distances above 15 km for the RC options do result in environmental impacts higher than those for CC.Conclusions
In summary, the current market mixtures of recycled concrete in Switzerland show significant environmental benefits compared to conventional concrete and cause similar GWP, if additional cement and transport for RC are limited.Purpose
This paper compares 16 waste lubricant oil (WLO) systems (15 management alternatives and a system in use in Portugal) using a life cycle assessment (LCA). The alternatives tested use various mild processing techniques and recovery options: recycling during expanded clay production, recycling and electric energy production, re-refining, energy recovery during cement production, and energy recovery during expanded clay production.Methods
The proposed 15 alternatives and the actual present day situation were analyzed using LCA software UMBERTO 5.5, applied to eight environmental impact categories. The LCA included an expansion system to accommodate co-products.Results
The results show that mild processing with low liquid gas fuel consumption and re-refining is the best option to manage WLO with regard to abiotic depletion, eutrophication, global warming, and human toxicity environmental impacts. A further environmental option is to treat the WLO using the same mild processing technique, but then send it to expanded clay recycling to be used as a fuel in expanded clay production, as this is the best option regarding freshwater sedimental ecotoxicity, freshwater aquatic ecotoxicity, and acidification.Conclusions
It is recommended that there is a shift away from recycling and electric energy production. Although sensitivity analysis shows re-refining and energy recovery in expanded clay production are sensitive to unit location and substituted products emission factors, the LCA analysis as a whole shows that both options are good recovery options; re-refining is the preferable option because it is closer to the New Waste Framework Directive waste hierarchy principle. 相似文献Technologies with low environmental impacts and promoting renewable energy sources are required to meet the energetic demand while facing the increase of gas emissions associated to the greenhouse effect and the depletion of fossil fuels. CO2 methanation activated by magnetic heating has recently been reported as a highly efficient and innovative power-to-gas technology in a perspective of successful renewable energy storage and carbon dioxide valorisation. In this work, the life cycle assessment (LCA) of this process is performed, in order to highlight the environmental potential of the technology, and its competitivity with in respect to conventional heating technologies.
MethodsThe IMPACT 2002+ was used for this LCA. The process studied integrates methanation, water electrolysis and CO2 capture and separation. This “cradle-to-gate” LCA study does not consider the use of methane, which is the reaction product. The functional unit used is the energy content of the produced CH4. The LCA was carried out using the energy mix data for the years 2020 and 2050 as given by the French Agency for Environment and Energy management (ADEME). Consumption data were either collected from literature or obtained from the LPCNO measurements as discussed by Marbaix (2019). The environmental impact of the CO2 methanation activated by magnetic heating was compared with the environmental impact of a power-to-gas plant using conventional heating (Helmeth) and considering the environmental impact of the natural gas extraction.
ResultsIt is shown that the total flow rate of reactants, the source of CO2 and the energy mix play a major role on the environmental impact of sustainable CH4 production, whereas the lifetime of the considered catalyst has no significant influence. As a result of the possible improvements on the above-mentioned parameters, the whole process is expected to reduce by 75% in its environmental impact toward 2050. This illustrates the high environmental potential of the methanation activated by magnetic heating when coupled with industrial exhausts and renewable electricity production.
ConclusionsThe technology is expected to be environmentally competitive compared with existing similar processes using external heating sources with the additional interest of being extremely dynamic in response, in line with the intermittency of renewable energy production.
相似文献Bio-based recycling systems and agricultural production using recycled materials are often evaluated separately. This study performs an environmental and socio-economic life cycle assessment (LCA) of a food waste treatment and spinach farming system in Japan. The environmental and economic tradeoffs of introducing a recycling system and the net environmental benefit of the substitution of market fertilizer considering operation changes are also examined.
MethodsThree scenarios were developed and compared. In the conventional (CV) scenario, food waste is collected, incinerated, and disposed of in landfill, and the farmer uses market organic fertilizer. The on-site composting (OC) scenario processes food waste using an on-site garbage disposer and transports compost to a nearby spinach farmer. Food waste in the centralized composting (CC) scenario is transported to a centralized composting facility and resultant compost is sent to the farm. Primary data were obtained from field experiments and interviews. Non-greenhouse gas (GHG) emissions from the field and nitrogen leaching to water systems were simulated using the denitrification–decomposition (DNDC) model.
The environmental LCA targeted climate change, eutrophication, and waste landfill. An input–output analysis estimated socio-economic indicators, namely gross added value and employment inducement effect.
Results and discussionThe scenario with the lowest impact is the CC scenario. Climate change and eutrophication impacts are highest in the OC scenario and waste landfill impacts are most significant in the CV scenario. The weighted impact by LIME2 can be reduced by 47% in the CC scenario and 17% in the OC scenario due to the recycling of food waste instead of dumping in the landfill. The difference in socio-economic indicators between the scenarios was relatively small, although the CV scenario encouraged more employment. The substitution effect of composting, as well as the environmental impact reduction of replacing market organic fertilizer with compost, will result in 28.7% of the avoided impacts in GHG emissions.
ConclusionsBoth composting scenarios are feasible from an environmental and socio-economic perspective when compared with conventional organic production, although there is a tradeoff between waste landfill and GHG emissions for the on-site composting system. However, the OC scenario needs to save electricity to improve its environmental competitiveness with the CV scenario. When considering the substitution effect of composting, it is recommended to take into account that agricultural operation also changes.
相似文献Purpose
The aim of this study is to develop and analyse a life cycle inventory of construction and demolition waste (C&DW) management systems based on primary data collected directly from Spanish enterprises involved in the life cycle of this type of waste material. Special emphasis is placed on assessing the environmental profile of inert waste sorting and treatment (IWST) facilities. 相似文献Characterization factors for biodiversity impact assessment derived from ecological zoning and land use classification have been proposed within life cycle assessment (LCA). However, their applicability to LCA of agricultural production systems has not yet been elucidated. This study clarifies correlations between regional-scale biodiversity indicators (characterization factors) and field-scale biodiversity indicators and estimates the degree of macro-micro inconsistencies in biodiversity indicators.
MethodsCorrelation coefficients were calculated between two types of variables. One is biodiversity (potential species loss) at the ecoregion level provided in UNEP/SETAC (2017) and Chaudhary and Brooks (2018), and the other is biodiversity (species richness) at the field level surveyed during a research project on biodiversity in Japan. The data on two taxa (amphibians and plants) in paddy fields were used for the analyses. Two types of correlation coefficients (the Pearson’s product-moment correlation coefficient and the Spearman’s rank correlation coefficient) were calculated. Uncertainties of the correlation coefficients were estimated by statistical resampling because the number of surveyed years and regions were limited.
Results and discussionAlthough in most cases the signs of the coefficients were consistent with theoretical expectations that the correlation between potential species loss and species richness must be negative, the absolute values were low for all cases (especially for the case of amphibians and for the case of using the UNEP/SETAC characterization factors). It was difficult to estimate field-scale biodiversity from ecoregion-scale biodiversity. The introduction of land use intensity into the calculation of biodiversity at the ecoregion-scale increased the correlation coefficients for plants. Uncertainties due to limitations in the number of surveyed locations were larger than those arising from limitations in the number of surveyed years. These results highlighted the existence of macro-micro inconsistencies and the necessity of developing constructive approaches for biodiversity assessment in agriculture.
ConclusionsIt is concluded that employing characterization factors based on ecoregions and land use categories was not useful when assessing the biodiversity impacts of rice production systems at the field-scale because of the existence of macro-micro inconsistencies. Use of field monitoring methods, in addition to approaches to construct biodiversity indicators based on management practices, will be necessary for establishing sustainable agricultural production systems.
相似文献Cotton yarns spun from natural fibers are widely used in the apparel industry. Most of waste cotton goods are now disposed by incineration or landfill, which brings resource and environmental challenges to the society. Using the waste cotton to spin yarns is an alternative way to forward a more sustainable future. In this research, two scenarios for the environmental impacts of yarns spun from corresponding fibers are investigated, including recycled cotton fibers and virgin cotton fibers.
MethodsThe life cycle assessment (LCA) has been conducted according to the collected data from on-site investigation of typical production factories. The life cycle for the recycled cotton yarn production is divided into five stages, i.e., raw material acquisition, transportation, breaking, mixing, and spinning. The life cycle of virgin cotton yarn production is been divided into four stages, i.e., raw material acquisition, transportation, mixing, and spinning. The functional unit is 1000 kg produced yarns which are used for weaving into the fabrics. Notable impacts on climate change, fossil depletion, water depletion, and human toxicity were observed.
ResultsThe life cycle impact assessment (LCIA) results show that environmental impacts of recycled cotton yarns are far less than those of virgin cotton yarns, except for climate change and water depletion. The reason is that the land occupation and irrigation water have great impact on environmental impacts of cotton cultivation. In spinning, the electricity is the key factor whose environmental impacts account for the most in the virgin cotton yarn scenario, while the electricity and water consumptions are the key factors for the recycled cotton yarn scenario in the life cycle of yarn production. The sensitivity analysis indicates that improving energy efficiency can significantly reduce environmental burdens for both the two scenarios. The uncertainty distribution of water depletion, human toxicity, fossil depletion, and climate change of the two scenarios were determined with a 90% confidence interval.
ConclusionsThe LCIA results reveal recycled cotton yarn is a viable alternative to relieve resource and environmental pressure. About 0.5 ha of agricultural land can be saved, 6600 kg CO2 eq can be reduced, and 2783 m3 irrigation water can be saved by using 1000 kg of the recycled cotton yarns. It can be concluded that the recycled cotton fibers can be served as a substitute for virgin cotton fibers to reduce agricultural land and avoid environmental impacts generated from the cotton planting.
相似文献Background, aim, and scope
When the service life (or primary life) of built concrete infrastructure has elapsed, a common practice is that the demolished concrete is crushed and recycled, then incorporated into new construction. LCA studies of CO2 emissions focus on the manufacturing and construction and occupancy/utilization phases, without consideration of the demolition and application of recycled concrete into a secondary construction application. Concrete has a documented ability to chemically react with airborne carbon dioxide (CO2); however, carbon capture (or carbonation) by concrete during the primary and secondary life, is not considered in LCA models. This paper incorporates CO2 capture during both primary and secondary life into an LCA model for built concrete. 相似文献Ocimum basilicum L. var. purpurascens is an enriched reservoir of pharmaceutically important compounds with plenty of health and therapeutic attributes such as phenolic acids and anthocyanins. However, the inefficient production of aforementioned metabolites in wild has restricted its commercial utilization. Herein, commercially viable phytochemicals have been enhanced through elicitation of in-vitro cultures of O. basilicum using yeast extract.The impact of various concentrations (YE 1 mg/L,YE 10 mg/L, YE 25 mg/L, YE 50 mg/L, YE 100 mg/L, YE 200 mg/L and YE 400 mg/L) of yeast extract on biomass accumulation, phytochemical production, and antioxidant activities were assessed in callus cultures. Moderate concentration of yeast extract (100 mg/L) enhanced biomass accumulation i.e. fresh weight (FW 216.28 g/L) and dry weight (DW 15.49 g/L) up to 1.5 folds as compared to control (FW 167.14 g/L and DW 10.25 g/L). Similarly, yeast extract (100 mg/L) increased total phenolic and flavonoid contents as well as enhanced antioxidant activities such as ABTS (2,2 azinobis 3-ethylbenzthiazoline-6-sulphonic acid), FRAP (ferric reducing antioxidant power) and DPPH (2,2-diphenyl-1-picryhydrazyl). High performance liquid chromatography (HPLC) analysis was elucidated for further phytochemical investigation. HPLC analysis showed an increase of almost 1.9 folds as compared to control in rosmarinic acid (15.19 mg/g DW), chicoric acid (2.13 mg/g DW), peonidin (2.70 mg/g DW) and cyanidin (1.57 mg/g DW). Likewise, 1.8 fold and 2.4 folds increase was observed in eugenol essential oils (0.25 mg/g DW) and chavicol (0.037 mg/g DW), respectively. For cellular antioxidant activity, reactive oxygen specie or reactive nitogen specie (ROS/RNS) was induced in yeast cells and the effect of O. basilicum callus culture was further investigated in stressed yeast cells. A positive correlation exists between the antioxidant activities, TPC and TFC analysis. In short, these results showed that yeast extract could act as an efficient elicitor to enhance pharmacologically important metabolites in callus cultures of Ocimum basilicum.
Graphical abstractSeveral models are available in the literature to estimate agricultural emissions. From life cycle assessment (LCA) perspective, there is no standardized procedure for estimating emissions of nitrogen or other nutrients. This article aims to compare four agricultural models (PEF, SALCA, Daisy and Animo) with different complexity levels and test their suitability and sensitivity in LCA.
MethodsRequired input data, obtained outputs, and main characteristics of the models are presented. Then, the performance of the models was evaluated according to their potential feasibility to be used in estimating nitrogen emissions in LCA using an adapted version of the criteria proposed by the United Nations Framework Convention on Climate Change (UNFCCC), and other relevant studies, to judge their suitability in LCA. Finally, nitrogen emissions from a case study of irrigated maize in Spain were estimated using the selected models and were tested in a full LCA to characterize the impacts.
Results and discussionAccording to the set of criteria, the models scored, from best to worst: Daisy (77%), SALCA (74%), Animo (72%) and PEF (70%), being Daisy the most suitable model to LCA framework. Regarding the case study, the estimated emissions agreed to literature data for the irrigated corn crop in Spain and the Mediterranean, except N2O emissions. The impact characterization showed differences of up to 56% for the most relevant impact categories when considering nitrogen emissions. Additionally, an overview of the models used to estimate nitrogen emissions in LCA studies showed that many models have been used, but not always in a suitable or justified manner.
ConclusionsAlthough mechanistic models are more laborious, mainly due to the amount of input data required, this study shows that Daisy could be a suitable model to estimate emissions when fertilizer application is relevant for the environmental study. In addition, and due to LCA urgently needing a solid methodology to estimate nitrogen emissions, mechanistic models such as Daisy could be used to estimate default values for different archetype scenarios.
相似文献Life cycle assessment (LCA) is a data-intensive methodology; therefore, experts usually focus collection efforts on a few activities, while generic data on remaining activities are taken from databases. Even though increased availability of databases has facilitated LCA takeoff, assuring data quality is fundamental to ensure meaningful results and reliable interpretation.
MethodsEcoinvent has become a global reference for inventory data. Its current version released three impact partition modeling options—the recycled content, “allocation at the point of substitution” (APOS), and consequential models—whose adequate choice is crucial for yielding meaningful assessments. Tutorials and manuals describe the distribution algorithm that backs each system model, to ground decision-making regarding the best fit to a study’s goals. We performed a systematic literature review to investigate—within the papers published on the International Journal of LCA (IJLCA)—how transparently authors addressed the system model choices.
Results and discussionAbout 70% of LCA practitioners continued to use earlier versions of ecoinvent after version 3 was launched in 2013. The number of papers using versions 3.x only showed an increased growth trend 2 years later. Eighty-three papers actually adopted the newest version of the database. From those, only 29 papers clearly mentioned the adopted system model. Our SLR also suggests a trend regarding authorship profile of LCA-related studies: the number of studies conducted by practitioners aware of the intricacies of sound modeling of background and foreground data might have been surpassed by those conducted by non-LCA specialists who use LCA as a supporting tool for investigations in applied fields, and merely scratch the surface.
ConclusionsOur results point to a need for a caveat: ecoinvent users must take time to understand the general concept behind each system model and practice one of the most important actions when performing an LCA—state methodological choices clearly.
相似文献Purpose
Polymer materials play an important role in the improvement and quality of life. However, due to their persistence in the environment, polymer materials may be harmful to the ecosystems. According to the European Directive on Packaging and Packaging Waste, management of these wastes should include prevention of their generation as a priority. The main motivation for employing ecodesign of a product is to reduce both raw material consumption and waste generation through a good initial design.Methods
In this study, life cycle assessment (LCA) was applied to the design of printed PVC plastic packing tape in order to reduce its environmental impact. LCA software GaBi4.4® was used to determine the PVC packing tape life cycle stage with the highest environmental impacts.Results and discussion
LCA results showed that PVC film manufacture was the stage with the highest impact. It was therefore reasonable to assume that packing tape manufactured with material other than PVC could have reduced environmental impact, and LCA was used to evaluate this hypothesis. When using Kraft paper or polypropylene plastic packing tape, the weighted impacts were reduced by 36.3 and 39.9 %, respectively.Conclusions
PVC plastic packing tape has been redesigned with the aim of reducing waste and raw material consumption. LCA results showed that a suitable option for reducing life cycle environmental impact is to use alternative film materials. Kraft paper and polypropylene plastic packing tape were found to give lower values of almost all environmental impact indexes and normalized and weighted impacts. 相似文献Waste recycling is one of the essential tools for the European Union’s transition towards a circular economy. One of the possibilities for recycling wood and plastic waste is to utilise it to produce composite product. This study analyses the environmental impacts of producing composite pallets made of wood and plastic waste from construction and demolition activities in Finland. It also compares these impacts with conventional wooden and plastic pallets made of virgin materials.
MethodsTwo different life cycle assessment methods were used: attributional life cycle assessment and consequential life cycle assessment. In both of the life cycle assessment studies, 1000 trips were considered as the functional unit. Furthermore, end-of-life allocation formula such as 0:100 with a credit system had been used in this study. This study also used sensitivity analysis and normalisation calculation to determine the best performing pallet.
Result and discussionIn the attributional cradle-to-grave life cycle assessment, wood-polymer composite pallets had the lowest environmental impact in abiotic depletion potential (fossil), acidification potential, eutrophication potential, global warming potential (including biogenic carbon), global warming potential (including biogenic carbon) with indirect land-use change, and ozone depletion potential. In contrast, wooden pallets showed the lowest impact on global warming potential (excluding biogenic carbon). In the consequential life cycle assessment, wood-polymer composite pallets showed the best environmental impact in all impact categories. In both attributional and consequential life cycle assessments, plastic pallet had the maximum impact. The sensitivity analysis and normalisation calculation showed that wood-polymer composite pallets can be a better choice over plastic and wooden pallet.
ConclusionsThe overall results of the pallets depends on the methodological approach of the LCA. However, it can be concluded that the wood-polymer composite pallet can be a better choice over the plastic pallet and, in most cases, over the wooden pallet. This study will be of use to the pallet industry and relevant stakeholders.
相似文献Life Cycle Assessment (LCA) is the process of systematically assessing impacts when there is an interaction between the environment and human activity. Machine learning (ML) with LCA methods can help contribute greatly to reducing impacts. The sheer number of input parameters and their uncertainties that contribute to the full life cycle make a broader application of ML complex and difficult to achieve. Hence a systems engineering approach should be taken to apply ML in isolation to aspects of the LCA. This study addresses the challenge of leveraging ML methods to deliver LCA solutions. The overarching hypothesis is that: LCA underpinned by ML methods and informed by dynamic data paves the way to more accurate LCA while supporting life cycle decision making.
MethodsIn this study, previous research on ML for LCA were considered, and a literature review was undertaken.
ResultsThe results showed that ML can be a useful tool in certain aspects of the LCA. ML methods were shown to be applied efficiently in optimization scenarios in LCA. Finally, ML methods were integrated as part of existing inventory databases to streamline the LCA across many use cases.
ConclusionsThe conclusions of this article summarise the characteristics of existing literature and provide suggestions for future work in limitations and gaps which were found in the literature.
相似文献