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PURPOSE: In life cycle assessment (LCA), literature suggests accounting for land as a resource either by what it delivers (e.g., biomass content) or the time and space needed to produce biomass (land occupation), in order to avoid double-counting. This paper proposes and implements a new framework to calculate exergy-based spatial explicit characterization factors (CF) for land as a resource, which deals with both biomass and area occupied on the global scale. METHODS: We created a schematic overview of the Earth, dividing it into two systems (human-made and natural), making it possible to account for what is actually extracted from nature, i.e., the biomass content was set as the elementary flow to be accounted at natural systems and the land occupation (through the potential natural net primary production) was set as the elementary flow at human-made systems. Through exergy, we were able to create CF for land resources for these two different systems. The relevancy of the new CF was tested for a number of biobased products. RESULTS AND DISCUSSION: Site-generic CF were created for land as a resource for natural systems providing goods to humans, and site-generic and site-dependent CF (at grid, region, country, and continent level) were created for land as a resource within human-made systems. This framework differed from other methods in the sense of accounting for both land occupation and biomass content but without double-counting. It is set operationally for LCA and able to account for land resources with more completeness, allowing spatial differentiation. When site-dependent CF were considered for land resources, the overall resource consumption of certain products increased up to 77 % in comparison with site-generic CF-based data. CONCLUSIONS: This paper clearly distinguished the origin of the resource (natural or human-made systems), allowing consistent accounting for land as a resource. Site-dependent CF for human-made systems allowed spatial differentiation, which was not considered in other resource accounting life cycle impact assessment methods.

Purpose The prominence of energy conservation in worship buildings like mosques, temples, and churches has led many nations to enact regulations for enhanced energy efficiency. However, the upfront costs often deter decision-makers. This research focuses on mosques, investigating cooling load reduction strategies and assessing their long-term cost dynamics. Methods To address the challenge of meeting energy requirements for community worship places, with mosques as a case study, this research conducted a comprehensive investigation. Various cooling load reduction strategies, both active and passive, are assessed to understand their impact on long-term cost dynamics. DesignBuilder V7.0.2 software is used for simulations. Results and discussion In a hot and dry climate context, this research carefully selected strategies like external shading, exterior wall insulation, R10 polystyrene roof insulation HRBLUE2 windows, night ventilation practices, and LED lighting systems, steered by environmentally aware construction principles. The objective is to determine the optimum means of management of cooling loads through a delicately adjusted cooling load strategy. Moreover, the life cycle cost related to those cooling strategies is determined. The recommendation includes implementation of strategies that effectively reduce cooling loads, decrease life cycle cost, and improve overall performance, specifically adapted for mosque environments. Conclusion This research emphasizes the crucial necessity for practicing sustainability in the construction of community buildings utilized for worship and the significance of energy conservation. By investigating cooling load decreasing strategies for mosques and their corresponding long-term cost implications, it suggests valuable solutions for addressing the energy needs of such places. The findings emphasize the importance of executing strategies that reduce cooling loads efficiently along with improving overall performance and minimize.

PurposeCarbon emission from roads is an important contributor of a nation’s greenhouse gas emission that causes climate change. However, the existing life cycle assessment (LCA) analysis of road carbon emissions focus on project-level, ignoring regional differences. Significant challenges remain in developing regional road’s carbon emission mitigation strategies. This study estimates the quantity of carbon emissions from roads in China and calculated the regional equity of road carbon emissions.MethodsAn improved LCA approach, which considered the regional difference of raw materials’ carbon emissions, carbon emissions caused by traffic jam and road category, was applied to calculate the quantity of carbon emissions of roads. Sensitive analysis was conducted to find the key influential factors. Gini coefficient was used to calculate the equity degree of carbon emissions by roads based on the LCA results. The decomposition model of Gini coefficient is applied to analyze the causes of carbon emission differences.ResultsThe total national carbon emissions by roads in 2019 increased by 2.2 times compared to 2009. Carbon emission from roads in the operation phase increased from 62% in 2009 to 83% in 2019. The functional unit for expressway in this study ranging from 1646 to 1794 t CO2e/km in 31 provinces. An estimated uncertainty of plus or minus 4% of the traffic flow allocation between expressway and other roads makes an increase of 38% or a decrease of 15% of the life cycle emission. The overall Gini coefficient of carbon emissions from roads in China is under the warning line of 0.4. Outer inequity between regions contributes 88.83% of the whole inequity and the most developed three regions contribute 66.23%.ConclusionsLarge quantity of road construction in the past in China makes the burden of carbon emission transfer from the construction phase to the operation phase. Regional differences of raw materials’ carbon emissions, traffic jam, and road hierarchy are important factors influencing the LCA-based estimation of road carbon emission. To improve the national equity degree of road carbon emission, quota allocation of road carbon emission rights between regions and cross-regional carbon emission reduction policies would help.

PurposePropylene oxide (PO) is one of the useful chemicals that is predicted to experience a compound annual growth rate of 3.9% from 2020 through 2027. The environmental burdens of the current PO production process and its corresponding utility system including power generation system need to be determined quantitatively as a response to increasing demands for its environmentally sustainable production process in the energy transition period from fossil fuels towards renewable energy resources.MethodsA new methodology is proposed to study the PO production process called exergy-aided environmental life cycle assessment (EELCA), using the US National Renewable Energy Laboratory’s database known as life cycle inventory (LCI) database. EELCA is dedicated to LCA studies of processes in the energy transition period and is aided by Monte Carlo simulation (MCS) as a tool for discernibility analysis which brings another dimension to the EELCA because MCS was often used to assess uncertainty in LCA studies. EELCA impact categories are classified into two classes: (i) emission-dependent impact categories addressed by ReCiPe and (ii) resource-dependent impact categories covered by cumulative exergy demand (CExD). The alternative energy like bioenergy is evaluated through the stepwise scenarios assisted by MCS, which are employed in openLCA with 10,000 iterations.Results and discussionThe cumulative exergy depletion of the base scenario is 6.1898 MJ (CExD). The human health and ecosystem impacts are 3.65E-06 DALY and 1.58E-08 species.yr, respectively. Human health-total (2.7E-4 DALY) is the most important category, where the power generation system by residual fuel oil (33.19%) is on top of the list. By analysing statistically discernible scenarios using EELCA, it has been proven that natural gas is not a proper choice for energy mix in the energy transition period. This is because natural gas-based scenarios present more burden compared to residual fuel oil-based scenarios especially regarding human toxicity, freshwater ecotoxicity, marine ecotoxicity, terrestrial acidification, and particulate matter formation. This study shows that the reduction in environmental impacts without changes in the production process technology is feasible through implementing bioenergy scenarios.ConclusionsHaving applied successfully EELCA, this study shows that PO production in the present configuration is not sustainable at all. The statistically discernible scenarios regarding energy mix selection help to enhance sustainability of the PO production process. Moreover, by examining the application of CExD along with LCA analysis, it is proved that by using the concept of CExD, we were able to represent the environmental impacts of the entire system with one figure, which tremendously facilitates the calculations in MCS.

PurposeThe purposes of this study were to quantify the resource consumption intensity of cement clinker production using natural mineral in China and to determine the influence of the utilization of calcium carbide sludge (CCS) for cement clinker production on the resource-accounting result.MethodsExergy-based resource accounting method was adopted by this study. Cumulative exergy demand (CExD) was used to characterize the resource consumption intensity of cement clinker production using natural mineral in China. Exergy-based characterization factors of land resource and CO2 emission were employed to determine the resource benefit brought by the substitution of CCS for natural limestone (land saving and CO2 reduction).Results and discussionThe CExD value of cement clinker production using natural mineral as raw material in China is 5005 MJ/t, and the consumption of raw coal is the largest contributor to this result, accounting for approximately 81% of the CExD value. The phenomenon that coal consumption dominates the CExD result may be because, through combustion reactions, the chemical state of carbon contained in coal almost reaches equilibrium with its chemical dead state in terms of exergy and is deeply dissipated; in comparison, the major chemical compound contained in limestone, i.e., calcium oxide, is mostly transformed into cement clinker by the reactions occurred in the production system, instead of being consumed in a deeply dissipated way and emitted to the environment. The major disadvantage of using CCS for cement clinker production is the increase of coal consumption, i.e., 515 MJ/t cement clinker, and the major advantage of using CCS for cement clinker production is the resource benefit brought by CO2 reduction (the avoided biotic resource damage in ecosystem), i.e., 1160 MJ/t cement clinker.ConclusionsFrom the analysis on the influence of the substitution of CCS for limestone on the resource consumption intensity, we found that the resource consumption intensity of the production system using CCS is approximately 15.5% lower than that of the production system using natural mineral; however, if this resource benefit is neglected, the resource consumption intensity of the production system using CCS is approximately 7.6% higher than that of the production system using natural mineral. We suggest that establishing a theoretical bridge between the characterization models of biotic resource and abiotic resource will still be a significant research direction in the future, which is fundamental in objectively understanding and unifying the issues of emission reduction and resource saving.

PurposeParticleboard is a composite panel comprising small pieces of wood bonded by adhesives. The particleboard industry is growing in Pakistan, but there is little information on the environmental impacts associated with this product. Therefore, the aim of this study was to develop a life cycle assessment of particleboard manufactured in Pakistan and to provide suggestions to improve its environmental profile. The study covers energy use and associated environmental impacts of raw materials and processes during particleboard manufacture in the year 2015–2016.MethodsThe study uses a cradle-to-gate (distribution center) life cycle assessment approach. The reference unit for this study was 1.0 m3 of finished, uncoated particleboard. Primary data from the particleboard mill surveys were combined with secondary database information and modeled using CML 2000 v.2.05 methodology and a cumulative exergy demand indicator present in the SimaPro v.8.3 software.Results and discussionThe results reveal that urea formaldehyde resin, transportation of raw materials, and finished product distribution had the highest contribution to all the environmental impact categories evaluated. Heavy fuel oil and natural gas consumption was responsible for abiotic depletion, photochemical oxidation, ozone layer depletion, and marine aquatic ecotoxicity impacts. The rotary dryer and hot press were the most important sectors in terms of emissions from the manufacturing process. The total cumulative exergy demand required for manufacturing of 1.0 m3 particleboard was 15,632 MJ-eq, with most of the energy usage associated with non-renewable, fossil fuel sources. A sensitivity analysis was conducted for a reduction in the quantity of urea formaldehyde resin consumed and freight transport distances.ConclusionsThe results indicated that reducing the urea formaldehyde resin use and freight distances could greatly decrease environmental impacts. Most of the surveyed mills did not have emissions control systems, and most of the mills exceed the limits set by the National Environmental Quality Standards of Pakistan. Environmental impact improvements might be attained by reducing quantity of urea formaldehyde resin and transportation freight distances and by installing pollution control devices.

Purpose Most existing methods for evaluating the national environmental impact of product manufacturing follow a top–down approach based on national annual statistical data. However, such approach fails to include many important data points and has a low level of quantification, which causes the difficulty in identifying insights on the location, causes, and characteristics of environmental problems. Hybrid life cycle assessment (LCA), which combines input–output data and process-based LCA, has recently been proposed and widely implemented for the collection of regional inventory. However, the limitation of using input–output data, which involves the adoption of averaging data associated with different inputs within various industry subsectors, has been highlighted. In this study, national and provincial statistical data combined with the bottom–up approach is used to solve the aforementioned problems and to assess the environmental effects of mechanical coke production at a national level. Methods A bottom–up approach combined with national and regional statistical data on product yield is used in this study to estimate the environmental effects and improvement potential of mechanical coke production at the national level. Results and discussion The total mechanical coke production and environmental burden generated by global warming, respiratory inorganics, and nonrenewable energy in 2010 were approximately 3.31 × 10 8  t, 1.01 × 10 8  t-CO 2 eq., 1.98 × 10 5  t PM 2.5 eq., and 1.05 × 10 10 GJ Primary, respectively. The highest coke production fluxes were found in Shanghai, followed by Tianjin, Hebei, Shanxi, Shandong, and Henan. The lowest coke production was observed in Hainan and Xizang. The difference can be attributed to coal mining and economic levels. From 2008 to 2012, the CO 2 , SO 2 , and NOx emissions as well as nonrenewable energy consumption for mechanical coke production accounted for 0.5 to 1.4, 1.5 to 2.2, 3.8 to 4.7, and 4.8 to 13.2 % of the total CO 2 , SO 2 , and NOx emissions and nonrenewable energy consumption in China, respectively. The following processes are highly important in reducing the environmental burden imposed by mechanical coke production in China: optimizing the transport distance and type, using underground coal washing technology, decreasing coke exports, and improving the efficiency of coking coal consumption, the average usage rate of seam gas drainage, the energy recovery rate of coke dry quenching technology, and the amount of imported coking coal. Conclusions The most significant processes, substances, and potential environmental impact categories that contribute to the overall environmental burden in China can be easily evaluated. The combination of national information, provincial statistical data, and LCA results on mechanical coke production represents a large group of LCA products that can further determine the key improvement factors for reducing the national overall environmental burden imposed by the manufacturing of mechanical coke.

PURPOSE: The purposes of this study are to quantify the natural resource consumption of primary aluminum production in China and to determine the resource-saving potential of aluminum in the transportation sector relative to steel. METHODS: In this study, exergy, which expresses both the quantity and the quality of a resource, was adopted for natural resource accounting. The cumulative exergy demand (CExD) of primary aluminum was calculated by the process analysis method, which begins in the final link of the fabrication of the considered product and runs through the production of semifinished products. This method can provide detailed information about each process. RESULTS AND DISCUSSION: The CExD value of 1 t of primary aluminum produced in China is 246,778 MJₑₓ, and the largest contributor to the CExD is electricity, which is mainly consumed in the electrolytic process. Compared with the CExD derived from the national average resource consumption data of alumina production (three techniques), if alumina was only produced by the Bayer process, the CExD of primary aluminum would decrease by 10 %. Taking wheel hubs as a case study, although aluminum wheel hubs have a lower natural resource consumption rate during the use phase relative to steel wheel hubs, no natural resource savings are obtained before a certain driving distance (breakeven distance) is reached because of higher resource consumption in the production phase. The total amount of natural resources that aluminum wheel hubs could save (relative to steel wheel hubs) over its lifetime driving distance is 3,652 MJₑₓ. In contrast, the breakeven distance derived from the CML model is approximately 80 % lower than that derived from the CExD model. CONCLUSIONS: A determination of the advantages of the Bayer process in terms of resource saving suggests that importing high-grade bauxite from abroad to promote the application of the Bayer process is an effective way to reduce primary aluminum’s CExD, i.e., resource intensity, in China. A comparison of the characterization results between the CML model (China’s own factors) and the CExD model shows that the CExD model assigns more weight to coal than to minerals, whereas the CML model assigns more weight to minerals.

PurposeThe work here focused on developing a framework for the overall planning of water distribution network (WDN) using life cycle energy analysis (LCEA) method. During the life cycle, aging-based maintenance scheduling was also carried out. Three different networks that have a distinguishing range of pipe diameter sizes and total pipe lengths were selected for study networks in order to evaluate the scale dependency to energy usage trend and design pathway.MethodsThe model is built up with a Visual Basic program, and the hydraulic network solver, EPANET 2.0, is linked to support simulation-based environmental assessment. The proposed model determines optimal diameter for minimum annual average energy usage (AAEU) while considering maintenance activities. For optimization, revised harmony search (ReHS) was selected, and also pipe aging and breakage models are used for maintenance scheduling. AAEU is calculated by dividing overall energy usage with life cycle. Proposed model is applied to three different scale WDN and demonstrated for three case studies. In the first case study, the proposed model was verified by comparing results with prior research studies. Then, LCEA was conducted for each of the network. Finally, an optimal design of each network was conducted.Results and discussionThe first case study results matched well to prior research studies, thereby demonstrating that the applicability of the proposed model was verified. Results of the second case study showed that the AAEU is proportional to the scale of network while life cycle is inversely proportional. Maintenance activity had advantage for extending the planning period. Finally, optimal design results in case study 3, both AAEU and life cycle are proportional to the scale of WDN. Comparing second and third case results, AAEU results were mostly influenced by the scale of network, but the length of life cycle was more dependent on the distribution of diameters. In summary, AAEU can be reduced using two methods either by increasing the number of small pipes or extending the life cycle.ConclusionsThe elicited results from the three cases are converging towards the importance of the pipe diameter distribution, number of small diameter pipes, and the total length of network. In order to reduce AAEU, the model considered the characteristics of the network and determined whether there are increases in the small diameter pipes or distributed diameters evenly. Results show that the suggested model could constitute an alternative design method for minimizing energy usage.

Purpose While life cycle assessment (LCA) has standardized methods for assessing emission impacts, some comparable methods for the accounting or impact assessment of resource use exist, but are not as mature or standardized. This study contributes to the existing research by offering a comprehensive comparison of the similarities and differences of different resource indicators, in particular those based on thermodynamics, and testing them in a case study on titania (titanium dioxide pigment) produced in Panzhihua city, southwest China. Materials and methods The system boundary for resource indicators is defined using a thermodynamic hierarchy at four levels, and the case data for titania also follow that hierarchy. Seven resource indicators are applied. Four are thermodynamics-based—cumulative energy demand (CED), solar energy demand (SED), cumulative exergy demand (CExD), and cumulative exergy extraction from the natural environment (CEENE)—and three have different backgrounds: abiotic resource depletion potential, environmental priority strategies, and eco-indicator 99. Inventory data for the foreground system has been collected through on-site interviews and visits. Background inventory data are from the database ecoinvent v2.2. Characterizations factors are based on the CML-IA database covering all major methods. Computations are with the CMLCA software. Results and discussion The scores of resource indicators of the chloride route for titania system are lower than that of the sulfate route by 10–35 %, except in terms of SED. Within the four thermodynamic indicators for resources, CED, CExD, and CEENE have similar scores, while their scores are five orders of magnitude lower than the SED score. Atmospheric resources do not contribute to the SED or CEEND score. Land resources account for a negligible percentage to the SED score and a small percentage to the CEENE score. Non-renewable resources have a dominant contribution to all seven resource indicators. The global production of titania would account for 0.12 and 0.14 % of the total anthropogenic non-renewable resource demand in terms of energy and exergy, respectively. Conclusions First, we demonstrate the feasibility of thermodynamic resource indicators. We recommend CEENE as the most appropriate one within the four thermodynamic resource indicators for accounting and characterizing resource use. Regarding the case study on the titania produced in China, all the resource indicators except SED show that the sulfate route demands more resource use than the chloride route.