Material Flow Research Articles

Simultaneous Formation of a Foldamer and a Self-Replicator by Out-of-Equilibrium Dynamic Covalent Chemistry.

Systems chemistry has emerged as a useful paradigm to access structures and phenomena typically exhibited by living systems, including complex molecular systems such as self-replicators and foldamers. As we progress further toward the noncovalent synthesis of life-like systems, and eventually life itself, it is necessary to gain control over assembly pathways. Dissipative chemical fueling has enabled access to stable populations of (self-assembled) structures that would normally form only transiently. Here, we report a synthetic dynamic combinatorial library, made from a single structurally simple building block, from which a self-replicator and a foldamer can emerge along two distinct and competing pathways through an inter- or intramolecular assembly process, respectively. A fueled chemical reaction cycle is then set up to generate the foldamer transiently, in the presence of the self-replicator. The partitioning of the building block between the folding and self-replication pathways and the duration of the fueled reaction cycles are controlled by adjusting the amount of the chemical fuel. An out-of-equilibrium steady state involving the two assemblies could also be achieved by using a continuous stirred tank reactor with inflow and outflow of material. This work connects the domains of folding and self-replication in synthetic systems through dissipative out-of-equilibrium chemistry. It demonstrates that foldamers and self-replicators, formed from the same building block, can stably coexist if the system is continuously supplied with energy, while at equilibrium, the Gibbs phase rule prohibits such coexistence.

Unraveling economic-environmental coupling in China's petrochemical industry towards carbon peaking

The petrochemical industry is a (key pillar) of chemical production and has relatively stable product demand in a long term, but it faces great decarbonization challenges due to the high energy consumption and complex industrial structure. To tackle this, a flow-land-infrastructure-petrochemical (FLIP) multi-factor model is developed with integration of material and energy flow analysis and decoupling assessment, targeting industrial carbon peaking via industrial structure upgrading and production efficiency improvement of four-digit level petrochemical sub-sectors. A nationally leading petrochemical industrial park was then selected to validate the model's effectiveness and robustness. Through the model optimization, the park could achieve 19 % and 30 % of CO2e emission reductions in 2025 and 2030 respectively, compared with emissions in the scenario without intervention. The overall carbon productivity could rise by 89 % with a decoupling index of -0.15 between economic growth and carbon emissions during 2020–2030, showing a feasible carbon peaking pathway. Infrastructure with lock-in emissions needs energy system transformation and adjacent industrial symbiosis from a regional perspective, while promotion targets and entry thresholds of carbon productivity should be individually tailored for each stock and incremental manufacturing sub-industry. The model could be extended to other petrochemical clusters and emission-intensive industries, synergistically addressing the effects of structure upgrading and efficiency progress to support practical and economically sustainable carbon peaking pathway formulation.

The implications of circular economy strategies on the future energy transition technologies and their impacts: Solar PV as a case study

Solar photovoltaics (PV) is expected to play a major role in global energy transition under the International Energy Agency Sustainable Development scenario (IEA-SD) to achieve the temperature goals of the Paris Agreement. However, its large-scale deployment will inevitably increase material demand and associated CO2 emissions. From a material-energy-carbon nexus perspective, this study assesses the effectiveness of various circular economy strategies and combinations in reducing material demand and mitigating carbon. This study is the first to explicitly explore the contradictions among reduce, reuse, recycle strategy combinations when addressing multiple sustainability objectives for different metal categories. A comprehensive analysis is conducted via dynamic material flow analysis and scenario analysis, covering four major metals (Al, Cu, Ni, Pb) and seven minor metals (Ag, Cd, Ga, Ge, In, Se, Te) used in four solar PV sub-technologies (c-Si, a-Si, CdTe, CIGS) at a global level for the period 2015 to 2050. Findings show that reduce & recycle combined can reduce cumulative Te demand to 100 % of available resources, and cut CO2 emissions for Ag by 94 %. However, when reuse is also applied, no further reductions in material demand are achieved, and cuts in CO2 emissions decrease to 92.5 %. Whereas for major metals, reuse & recycle combined achieve the highest cuts in CO2 emissions at 23.1 %, with recycle only accounting for 4.4 % of this cut. These results challenge the conventional wisdom of applying a universal set of circular economy strategies, implying that circular economy strategies should be selectively implemented based on specific sustainability objectives and target materials.

Reuse of building materials—the perspective of Swedish clients

In the context of the circular economy, there is an urgent need for transformation into circular material flows by avoiding waste, reducing extraction of virgin raw materials, and extending product life cycles. Within the construction and real estate industry, the reuse of building materials stands out as a critical strategy for value retention. The objective of this paper is to localise the forefront of the practical implementation of reused materials within the Swedish construction and real estate industry. To achieve this, the current state of reuse practices through the perspective of property companies as clients in decision-making positions was conducted through semi-structured interviews to identify key barriers and enablers associated with reuse. The three most significant barriers that emerged were a lack of measurable economic incentives, the absence of a professional reuse market, and obsolete project management. Conversely, the three most significant enablers were new and improved project management methods, enhancing competence and learning within and beyond organisations, and introduce reuse at an early stage. The results emphasise the need for project management to develop and adopt circular economy principles. This is further understood due to responders highlighting the industry's linear approach as a major obstacle to circularity together with uncertainties related to product performance, responsibilities and economics characterising reuse efforts. However, an industry in transition is witnessed, e.g. by the emergence of new roles which suggests a continued need for focused research in organisational matters.

Material Flow Analysis: An Analytical Tool for Strategic Planning Towards a Zero-Waste Solution for End-of-Life Ballast Flows on a Track and Ballast Renewal Site (French Conventional Line)

The 27,000 km of railway track in France represents approximately 100 million tonnes of ballast. This ballast requires maintenance approximately every 7 years, screening and partial renewal every 20 years, and complete replacement every 40 years. Despite its shortcomings, ballast is still widely used on railways worldwide, as there is no better or more efficient solution currently available. In an effort to conserve resources, companies such as SNCF (French national railway company) are implementing initiatives to move towards zero waste. In order to achieve the goal of promoting the recycling and recovery of end-of-life material flows, it is necessary to develop specific studies and models for production, such as direct and reverse logistics systems. This article proposes a generic material flow analysis model applied to a track and ballast renewal site, aiming to fill a gap in the literature. It is based on data from eleven track and ballast renewal sites. A flow diagram generated by STAN software presents a detailed diagnosis of ballast inputs, outputs, and stocks, including data uncertainty. The distribution of the material flows through the model is characterized by transfer coefficients in various transformation processes. Furthermore, by varying the quantities in this model, it is possible to study different scenarios based on the current situation. This will facilitate the projection and analysis of future management strategies aimed at achieving zero waste and reducing the discharge of toxic substances based on specific performance indicators.

MESSAGEix-Materials v1.1.0: representation of material flows and stocks in an integrated assessment model

Abstract. Extracting raw materials and processing them into products used in industry constitute a substantial source of CO2 emissions, which are currently lacking process detail in many integrated assessment models (IAMs). To broaden the space of climate change mitigation options to include material-oriented strategies such as the circular-economy and material efficiency measures in IAM scenario analysis, we develop the MESSAGEix-Materials module, representing material flows and stocks within the MESSAGEix-GLOBIOM IAM framework. We provide a fully open-source model that can assess different industry decarbonization options under various climate targets for the most energy- and emissions-intensive industries: aluminum, iron and steel, cement, and petrochemicals. We illustrate the model's operation with a baseline and mitigation 2-degrees (2 °C) scenario setup and validate base year results for 2020 against historical datasets. We also discuss the industry decarbonization pathways and material stocks of the electricity generation technologies resulting from the new model features. The next steps are to extend the model to other sectors, end uses and materials, as well as the combined modeling of various supply- and demand-side measures.

Impact of tool geometry and friction stir welding parameters on AZ31 magnesium alloy weldment wear behaviour and process optimization

This study investigates the impact of friction-stir welding (FSW) tool pin shape (TPS) and processing variables, viz., rotation speed (RS), axial load (AL), and traverse speed (TS), on weld beads’ wear characteristics as per ASTM G99 standard. Wear rate (WR), friction force (FF), and coefficient of friction (CoF) are analyzed based on Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). FSW performed with a hexagonal TPS provides a better material flow between the plates, influencing the joint’s strength and improving the wear resistance of weldments. Higher RS leads to high material flashing, providing lower strength and wear properties. Changes in TPS from triangle to pentagon and from pentagon to hexagon produced higher tensile strength, at 11.16% and 12.15%, respectively. The Chimp Optimization Algorithm (ChOA) shows an optimal condition of hexagon TPS, AL of 2 kN, RS of 1800 rpm, and TS of 25 mm/min, whereas TOPSIS optimal condition are hexagon TPS, AL of 4 kN, RS of 1400 rpm, and TS of 50 mm/min. Confirmation experiments with optimal conditions shows, ChOA producing lower WR, CoF, and FF by 12.5, 2.56, and 1.54% than TOPSIS. Compared with TOPSIS, ChOA produced lower WR, CoF, and FF by 12.5%, 2.56%, and 1.54%.

Environmental, energy, and economic (3E) assessment of viticulture systems.

Given the current trends, it seems obvious that temperatures and atmospheric carbon dioxide levels will rise over the coming years. To deal with climate change, a gradual transition to more sustainable viticulture operations is required. It seems necessary to carry out accurate local studies for future projections. The purpose of the current study was to choose the best grape production system in Jowzan Valley, Malayer, Iran. This region was registered by FAO as a Globally Important Agricultural Heritage System (GIAHS) in 2018. This study seeks to answer the question: if climate change has occurred in the Malayer region, which of the traditional and trellis systems is more sustainable from economic, energy, and environmental aspects? The sixth phase of the Coupled Model Intercomparison Project (CMIP6) was used to project the climate parameters of Malayer in the past and the future. The output of climate models based on rainfall, temperature, and wind (as factors influencing grape yield) in the observation period of 1992-2021 (the base period) and forecasting the future period of 2021-2100 under three scenarios (SSP1-26, SSP2-45, and SSP5-85) were obtained. The determination of hotspots in terms of cost, energy, and environment for two production systems was done with the approaches of material and energy flow cost accounting (MFCA) and life cycle assessment (LCA). The results of these two approaches help us know which of the two systems are currently more sustainable in terms of economic, energy, and environmental aspects. Grape production in 1 hectare was chosen as a functional unit (FU). The system boundary included the foreground processes that the farmer was directly involved in managing. Grape data were collected in the crop year of 2021-2022 from the vineyards of Jowzan region. According to results, under SSP1-26, SSP2-45, and SSP5-85 scenarios, the annual mean temperature is expected to rise at rates of 0.27, 0.477, and 0.82°C 10a-1 in the future (2021-2100), respectively. From an economic point of view, labor was recognized as the main input. By changing the system from traditional to trellis, production costs can be expected to be halved. The main hotspot in terms of negative products was the loss of grapes during production or harvesting. Such conditions were also true in terms of energy. From the environmental aspect, on-farm emissions and electricity were identified as hotspots. These effects are greatly reduced in the trellis system compared to the traditional system. In the case of changing the system from traditional to trellis, these effects can be reduced to a reasonable extent by improving the efficiency of irrigation and fertilizer distribution through the irrigation system. According to the results obtained from the climate scenarios as well as the results of the economic, environmental, and energy evaluation of the two production systems, it can be concluded that the use of the trellis system can be more sustainable than the traditional system.

Using dynamic release modeling to predict historic and current macro- and microplastic releases

Confronting the pervasive challenge of plastic pollution, our study pioneers a dynamic release model to quantify the historic and current plastic emissions. Utilizing Dynamic Probabilistic Material Flow Analysis (DPMFA) coupled to a release model, we comprehensively tracked emissions of macro- and microplastics in Switzerland from 1950 to 2022, covering 35 product categories and 183 release pathways for seven polymers (LDPE, HDPE, PP, PS, EPS, PVC, PET). The plastic usage exhibited a “Peak Plastic” around the year 2010 with a subsequent decrease in per capita use of plastics from 120±5 to 107±5 kg/cap in 2022. Over the considered timeframe, 27±1 kg/cap of macroplastics and 4 ± 1 kg/cap of microplastics were released to the environment, with the most substantial contributions coming from LDPE and PET. The overall emission factor was 0.66±0.07 % for macroplastics and 0.010±0.01 % for microplastics. The model can provide a crucial framework for crafting targeted interventions toward sustainable plastic lifecycle management.

Enhanced material flow and joint formation of FSWed AA2024 by using protruding cylinder tool

The optimization mechanism of the protruding cylinder on the modified tool for the performance of friction stir welding (FSW) joints in 2024 aluminum alloy was investigated. The results indicate that the presence of a protruding cylinder on the modified tool significantly improves the surface quality of the weld, increases the width and area of the weld nugget zone(WNZ), and refines the grain size. Additionally, the size of the precipitated phases is reduced, and their distribution becomes more uniform, which in turn enhances the tensile strength and hardness of the joint. Furthermore, the presence of a protruding cylinder facilitated material flow, stabilized the welding process, and contributed to the formation of uniform welds.

Threads untangled: Regional mapping of post-consumer textile management

In the coming decade, the EU intends to intervene in the textile value chain to steer it towards sustainability and circularity. As part of this effort, post-consumer textile (PCT) management should align with the waste hierarchy. This study employs material flow analysis (MFA) to examine and compare PCT management in two European regions: Flanders (Belgium) and the Netherlands. Additionally, future scenarios provide insights into transformations of PCT management toward 2030. The results show that Flanders outperformed the Netherlands in 2018, with a higher share of PCTs being collected separately, going to product recovery, local reuse, and material recovery. However, in both regions, there is still much potential to increase the recovery of products or materials. In 2018, local reuse was at only 4 % in Flanders and 2 % in the Netherlands. Most materials were still lost through incineration, with 52 % in Flanders and 62 % in the Netherlands. Even so, the future scenarios indicate that the Netherlands’ greater policy ambitions, with specific targets aimed at higher circular strategies, such as local reuse and closed-loop recycling, can result in more circular PCT management toward 2030. Hence, when designing interventions, policymakers should go beyond targets on separate collection to successfully steer the waste management of PCT toward circularity. This study shows how MFA-based monitoring provides a good overview of a specific system, allowing for a high level of transparency. Therefore, monitoring PCT management is key to developing informed policies and effective targets.

Mapping the anthropogenic zinc cycle in China from 2000 to 2021: A dynamic material flow analysis

Zinc is one of strategic metals for economic advancement owing to its extensive utilization in various sectors. China is the largest zinc producer and consumer in the world and plays an important role in the global zinc supply chain. However, a clear picture of zinc metabolism, including its flows and stocks, remains unclear in China. This study investigates the anthropogenic zinc cycle within China's mainland for a period of 2000–2021 by employing a dynamic material flow analysis approach. Our results indicate that the demand for zinc ores increased from 1.86 Mt (megatons) in 2000 to 7.77 Mt in 2021, while the domestic zinc consumption increased from 1.51 Mt in 2000 to 6.39 Mt in 2021. In the use stage, galvanized zinc products dominated zinc consumption with a proportion of 62.49%, with the construction sector serving as the largest end-user with a proportion of 44.17%. However, the average zinc recycling rate was only 49.4%, primarily from new scraps collected in the manufacturing stage. In order to respond to the ambitious carbon neutrality target and rapid urbanization, the Chinese government has implemented mining restriction policies to curb domestic emissions, which induced more zinc imports. Consequently, the reliance on international trade increased from 27.57% in 2013 to 46.77% in 2021. Based upon these findings, several policy recommendations are proposed, including preparing regulatory frameworks, promoting technological advancements, and applying various economic instruments. These recommendations can facilitate sustainable zinc resource management.

Exploring the effective reuse rate of materials and elements in the construction sector

In North-West European countries, the uptake of reusing construction elements following their first use in a building is still low. Although a large number of elements are technically reusable, they end up being recycled by crushing ormelting, or simply disposed of. This results in a high environmental impact and a net loss of economic value. This study aims to define a framework that can guide project managers, public and local authorities, as well as other organisations in setting, measuring, and reporting rates of material reuse in construction and renovation projects. To support this, a retrospective analysis was conducted on 32 construction and renovation projects that have incorporated reclaimed elements. To quantify the effective reuse rates, the data are categorised according to the types of work, functional layers, and type of projects. In summary, achievable reused targets can be determined for the structural layer (1–5% in mass), skin layer 5–15 % in mass), space plan layer (10–25 % in mass), and for outdoor surfaces (0–50 % in mass). Results confirm the contextual nature of reuse practices, emphasising that the achieved rates of reuse are linked to project types in specific layers, and depend on the overall quantity of materials in a project. It also underscores the importance of integrating reuse rate calculations proactively at the beginning of the project, particularly during the preparation of the bill of quantities. This can be accomplished by utilising appropriate procurement strategies, as-built documentation, monitoring material flows during works, and establishing a detailed record of reclaimed building elements.

Human activity controls nitrogen loads in a large sub-tropical delta from 2000 to 2020

Nitrogen (N) is crucial for agricultural yield, but its overuse in fertilisation and presence in uncollected wastewater from urbanization causes eutrophication. The Red River Delta in Vietnam is facing rapidly increasing water quality issues. Here, Material Flow Analysis is applied to quantify N flows in the delta between 2000 and 2020. This novel long-term assessment of changes in rice fertilisation regimes (human excreta, livestock manure and chemical fertilisers), demonstrates dramatic changes in N flows to surface water. The model shows a 41 % increase in rice paddy N use, with chemical fertilisers rising 1.6-fold while manure-derived N declined to 36 %. The total N load into surface water in 2020 increased by 53 % compared to 2000. The “hidden” inflows of domestic wastewater and blackwater into rice fields, which contribute significantly and indirectly to N loads, were identified via the MFA model. This underscores the need for improved fertilisation practices and waste management to mitigate freshwater pollution.

The “nature” and “nurture” of product lifetimes in dynamic stock modeling

AbstractProduct life extension is often portrayed as one of the pillars of the circular economy since longer lifetimes slow down material turnover rates and thus decrease resource use and associated emissions. Strategies for product longevity can involve addressing the product “nature” (inherent product durability) or “nurture” (external factors). Yet, in most dynamic material flow analysis (dMFA) studies, lifetime is an intrinsic property of the cohort assigned “at birth,” so “nurture” strategies such as repair or reuse cannot be explicitly considered. Here, we introduce a Python‐based tool for comprehensive modeling of lifetime changes in dMFA, including three dimensions of lifetime: age, period (time), and cohort. The tool employs the hazard function, which directly links the outflow to the preceding year's stock, allowing for differentiating the influence of product nature and nurture on lifetimes. The tool supports dynamic stock and flow calculations and is compatible with ODYM, a commonly used dMFA framework. We apply the tool to a case study on dishwashers in Norway to illustrate nature‐ and nurture‐focused lifetime extension strategies. The framework enables linking product lifespans with events such as economic crises and pandemics. It can serve to model life extension scenarios in dMFA that (i) extend the lifetime not only of the new products entering use but also of the products already in use, thus achieving faster effects; and (ii) expand the group of potential stakeholders beyond producers and designers to, for example, consumers, repairers, and resellers. This article met the requirements for a gold‐gold JIE data openness badge described at http://jie.click/badges.

Mission-Oriented Research and Theory of Change: Driving Australia’s Transition to a Circular Economy

AbstractAustralia’s linear economic system hinders the collective pursuit of sustainability, equity, and well-being. As demands for housing, food, energy, transportation, and goods escalate, transitioning to a circular economy becomes imperative. Such a transition necessitates a transformation in business and governance models, as well as cultural shifts, to foster sustainable material flows. The proposed change will likely unfold in five phases: envisioning a circular economy future, evaluating options and trade-offs, initiating local actions, amplifying national efforts, and solidifying global agreements. This shift will occur within the context of significant technical, environmental, social, and economic megatrends, and each phase is likely to overlap with the next, with some phases occurring concomitantly and ongoing. It will reshape socio-technical systems and social practices that fulfil our essential needs. Moreover, this transformation process is inherently circular, characterised by continuous cycles of learning, adaptation, and risk management.

Material matters: Recommendations for the analysis of relational spaces in sociotechnical transition studies

This article examines the interplay between materiality, relational spaces, and technological change dynamics. The objective is to introduce a novel theoretical perspective and a structured analytical process designed to enrich the investigation of relational spaces within the context of sociotechnical transitions. Our perspective aims to help transition scholars integrate the often-overlooked importance of material arrangements with the analysis of material flows and social components. We interpret this integration as a morphological approach to the analysis of relational spaces. The development of our perspective is grounded in a thorough review of existing literature on transition studies, complemented by the application of the theory of space constitution. Through our theoretical contribution, we advance the spatial discourse in transition studies, offering the means required to produce novel insights into how diverse social and material dimensions of spatial contexts affect, and are affected by, sociotechnical transition pathways and the technological change they produce.

Carbon Footprint of Additively Manufactured Precious Metals Products

Traditionally, precious metals are processed by either lost-wax casting or the casting of semi-finished products followed by cold or hot working, machining, and surface finishing. Long process chains usually conclude in a high material input factor and a significant amount of new scrap to be refined. The maturing of Additive Manufacturing (AM) technologies is advantageous with regard to resources among other criteria by opening up new processing techniques like laser-based powder bed fusion (LPBF) for the production of near net shape metal products. This paper gives an insight into major advantages of the powder-based manufacturing of precious metal components over conventional methods focusing on product carbon footprints (PCF). Material Flow Cost Accounting (MFCA) for selected applications show energy and mass flows and inefficient recoverable losses in detail. An extended MFCA approach also shows the greenhouse gas (GHG) savings from avoiding recoverable material losses and provides PCF for the products. The PCF of the precious metals used is based on a detailed Life Cycle Assessment (LCA) of the refining process of end-of-use precious metals. In the best case, the refining of platinum from end-of-life recycling, for example, causes 60 kg CO2e per kg of platinum. This study reveals recommended actions for improvements in efficiency and gives guidance for a more sustainable production of luxury or technical goods made from precious metals. This exemplary study on the basis of an industrial application shows that the use of AM leads to a carbon footprint of 2.23 kg CO2e per piece in comparison with 3.17 kg CO2e by conventional manufacturing, which means about a 30 percent reduction in GHG emissions and also in energy, respectively.

Image‐based prediction of residential building attributes with deep learning

AbstractThis study estimates building attributes—floor area and age—using image‐based machine learning. Building age and floor area are key inputs to the studies of urban metabolism, material stocks and flows, and embodied greenhouse gases (GHGs) in the built environment. However, these data are challenging to generate and maintain using traditional survey methods, their availability is uneven and often, even when available, very uncertain. Improving our understanding and future management of built environment resource flows and associated environmental impacts requires more complete access to building age and floor area data. The study formulates area prediction as a regression problem and age prediction as a classification problem over six historical periods, achieving a mean absolute percentage error of 19.42% for area prediction and an accuracy of 70.27% for age prediction in Toronto. These results are obtained using an EfficientNetV2 module for feature extraction from Google Street View images, followed by fully connected layers for estimating the two building attributes. The performance of the Toronto‐trained model in five other Canadian cities is also reported, highlighting the model's varying effectiveness in different urban contexts and the benefit of local training. Our findings demonstrate the feasibility of using machine learning for building attribute estimation from street‐view images, offering a basis for future automated large‐scale material flow and stock analysis.

Material Flow and Microstructural Evolution in Friction Stir Welding of LAZ931 Duplex Mg-Li Alloys

The material flow behavior during friction stir welding (FSW) plays a critical role in the quality of final joints. In this study, the FSW of LAZ931 duplex Mg alloy was carried out at a rotation speed of 800 rpm and welding speeds of 50, 100, and 200 mm/min, respectively. A thin pure Mg strip inserted at the interface between the two Mg-Li alloy plates was used as a marker to study the flow behavior of the materials in the FSW process. Sound welds with no defects were obtained for all three welding speeds. The microstructural evaluations along the marker on the horizontal cross-section around the keyhole of the welds were characterized. As the welding speed increased, the marker came closer to the keyhole, indicating the decreased extent of the plastic deformation of the material. In the shoulder-affected zone (SAZ), the thickness of the marker reduced gradually in the accelerating stage and finally accumulated together in the decelerating stage. However, in the pin-affected zone (PAZ), the thickness of the marker reduced sharply in the accelerating stage and then became dispersed in the decelerating stage, and the degree of dispersion decreased as the weld speed increased. As a result, an elongated grain structure was formed in the SAZ, while two equiaxial grain structures were formed in the PAZ. The material on the advancing side was refined by the pin and deposited in the weld to form a fine equiaxial grain structure due to the high strain rate. In contrast, the material on the retreating side was pushed by the pin and thus directly deposited in the weld to form a coarse equiaxial grain structure. In addition, the area of the fine equiaxial grain structure was reduced obviously with the increase in welding speed.