Material Flow Analysis Model Research Articles

An interlinked dynamic model of timber and carbon stocks in Japan's wooden houses and plantation forests

Carbon absorption in growing trees is an important element of a carbon-neutral society, and the long-term storage of carbon stocks is a crucial sustainability challenge. Previous studies have focused on either live-biomass carbon stocks in plantation forests or anthropogenic carbon stocks in man-made objects. For a comprehensive nature-based climate solution, an analytical framework, dataset, and scenario setup for modeling the interrelationship between timber supply and demand are required. This study developed an interlinked material flow analysis model in which the timber demand for wooden houses is connected with timber supply from managed plantation forestry. We demonstrate the model by quantifying both live-biomass and anthropogenic carbon stocks and their potentials in Japan. We compared multiple scenario-runs of the model for wooden house demands estimated by population change with varying combinations of house types, structures, and lifespans. Our results show that carbon stocks will reach a maximum amount of 1.1 billion t-C by 2050 in a scenario of high demand for wooden detached houses with lifespan extensions. On the other hand, we also found that the aging of plantation forests and their reduced carbon-stocking capacities appear inevitable in any scenario owing to the limited demand for timber. Notably, despite the widely different settings of the various scenarios, our results exhibited narrow variances in future potential carbon storage in Japan. This can be explained by the unique population characteristics and building demographics of Japan. These counterintuitive findings highlight the need for interrelated modeling of the forestry and construction sectors. Our model and its scope are versatile and applicable to other case study areas, estimation periods, and target materials.

Assessment of Plastic Waste Generation and Environmental Leakage in Hai An Ward, Nghi Son Town, Thanh Hoa Province

The study estimates plastic waste generation and leakage to the environment and the sea in Hai An ward, Thanh Hoa province. The study uses a material flow analysis model, field samplings (include plastic waste sorting and weighing), and secondary data collection and analysis. The plastic waste generated is estimated to be 77.01 ton/year, of which the plastic waste from domestic sources and other sources, including agriculture and aquaculture (fishing), are 71.17 ton/year and 5.84 ton/year, respectively. Research results show the composition of plastic waste from domestic sources is diverse, with bottles being the highest (28.4%), followed by plastic bags (23.1%). The findings of the study also indicate that the plastic waste leakage to the environment is 9.63 ton/year, of which 6.4 tons are from the uncollected plastic waste and 3.23 tons are the plastic waste lost during the collection, transportation, and treatment process. The research also estimates that the plastic waste leakage to the sea accounts for about 7.24 ton/year, plastic waste retained on land is about 2.16 ton/year, and the plastic waste openly burnt is 0.23 ton/year.

Pathways to a net zero building sector in Colombia: Insights from a circular economy perspective

The rapid urbanization and economic growth in Colombia have made the residential sector one of the largest energy and material consumers in the country. Circular economy (CE) strategies are a promising alternative to decouple the sector from resource depletion and climate change. The analysis shown here is based on the RECC model framework, a dynamic material flow analysis (dMFA) model. Our results suggest that by 2050 without CE strategies, residential building stock will reach 2.5 billion m2 and emit between 13 and 25 Mt CO2/yr, depending on whether carbon forest sequestration is included or not. A complete implementation of CE strategies and lower floor space can reduce 2020–2050 cumulative primary material production, waste generation, and GHG emissions by 48, 5, and 49 %, respectively. There is a potential to achieve net zero emissions by 2050 if, in addition to the measures mentioned above, more wood materials and forest sequestration are considered.

Modeling Aluminum Stocks and Flows in China until 2050 Using a Bottom-Up Approach: Business-As-Usual Scenario Analysis

Aluminum metal is used in a wide range of applications such as construction, transportation, power, and aerospace. Previous studies have mainly used a top-down approach to explore future aluminum stocks and flows in China. In this study, we developed a dynamic material flow analysis model using a bottom-up approach to simulate aluminum flows and stocks in China until 2050, based on current government and sector policies. The results show that China’s aluminum stocks will be nearly saturated by 2050, with a total and per capita of 591 million tons (Mt) and 449 kg/per, respectively. The domestic demand for aluminum will grow until 2030 and will remain relatively stable thereafter at around 28–30 Mt. Construction and transport are the two sectors with the highest demand for aluminum, accounting for over 60% of the total aluminum demand. The domestic aluminum scrap will increase almost sevenfold, from 2.7 Mt to 20.0 Mt between 2020 and 2050. However, even assuming a 90% recycling rate, secondary aluminum will at best meet around 70% of demand by 2050. To realize sustainable development in China’s aluminum industry, extending the life of aluminum products and increasing aluminum scrap recycling are sensible measures.

Rethinking time-lagged emissions and abatement potential of fluorocarbons in the post-Kigali Amendment era

The Montreal Protocol has been successful in safeguarding the ozone layer and curbing climate change. However, accurately estimating and reducing the time-lagged emissions of ozone-depleting substances or their substitutes, such as produced but not-yet-emitted fluorocarbon banks, remains a significant challenge. Here, we use a dynamic material flow analysis model to characterize the global stocks and flows of two fluorocarbon categories, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), from 1986 to 2060. We assess emission pathways, time-lagged emission sizes, and potential abatement measures throughout different life cycle stages while focusing on the role of banked fluorocarbons in global and regional decarbonization efforts in the post-Kigali Amendment era. Although fluorocarbon releases are expected to decline, the cumulative global warming potential (GWP)-weighted emissions of HCFCs and HFCs are significant; these will be 6.4 (±1.2) and 14.8 (±2.5) gigatons CO2-equivalent, respectively, in 2022–2060 in our business-as-usual (BAU) scenario. Scenario analysis demonstrates that implementing currently available best environmental practices in developed economies can reduce cumulative GWP-weighted emissions by up to 45% compared with the BAU scenario.

Understanding key mineral supply chain dynamics using economics‐informed material flow analysis and Bayesian optimization

AbstractThe low‐carbon energy transition requires significant increases in production for many mineral commodities. Understanding demand, technological requirements, and prices associated with this production increase requires understanding the supply chain dynamics of many minerals simultaneously, and via a consistent framework. A generalized economics‐informed material flow method, global materials modeling using Bayesian optimization, captures the market dynamics of key mineral commodities. The method relies only on a limited set of widely available historical data as input, enabling quantification of economic relationships (elasticities) for supply chain components where data are sparse, and relationships cannot be obtained via traditional statistical approaches. Building upon established material flow analysis (MFA) and economic modeling techniques, Bayesian optimization was applied to fit an economics‐informed MFA model to global historical demand, supply, and price for aluminum, copper, gold, lead, nickel, silver, iron, tin, and zinc. This approach enables estimates for the evolution of ore grades, mine costs, refining charges, sector‐specific demand, and scrap collection for each commodity. Economic relationships were quantified and compared with a database compiled from the literature, including 1333 values from 213 analyses across 65 publications. Discrepancies in methods and limited coverage make use of these parameters in modeling efforts difficult. This work provides a single, homogeneous, probabilistic approach to identifying economic relationships across mineral supply chains, with uncertainty quantification, a literature database for comparison, and a modeling framework in which to use them. This article met the requirements for a Gold‐Gold JIE data openness badge described at http://jie.click/badges.

Research on the Economic Environmental Impact and Carbon Reduction Pathways of Power Battery Industry Development - A Case Study of Yibin City

Abstract The power battery industry in China is experiencing rapid development, with the swift expansion of capacity potentially posing challenges to environmental protection and carbon reduction. Using the development plan of the power battery industry in Yibin City as a case study, this paper employs the Material Flow Analysis and Tapio decoupling model to deeply explore the economic benefits and environmental burdens brought by the development of power battery key industry under scenarios, proposing optimized pathways to promote low-carbon industrial development. The results indicate that the industrial output value can increase from 92.1 billion CNY in the baseline year to 382.6 billion CNY in 2030, with carbon emissions rising from 0.55 million tons to 2.32 million tons. The adjustment of product structure has limited effect on carbon reduction in the power battery industry. In the short term, optimizing the energy structure has greater carbon reduction potential than improving energy efficiency, and clean energy utilization has the highest marginal carbon reduction effect. Implementing measures to optimize the energy structure and improve efficiency simultaneously can achieve weak decoupling of economic growth and carbon emissions, though strong decoupling is challenging to attain. The proportion of local renewable energy generation also impacts the low-carbon capability of the industry, suggesting that regions with abundant renewable energy should be prioritized for industrial layout. Promoting the decoupling of economic growth and environmental impact in the power battery industry can be facilitated by supporting environmental governance infrastructure, driving the green energy transition, and encouraging low-carbon technological innovation. JEL classification numbers: F062.2 Keywords: Power battery, Scenario analysis, Material flow, Economic environmental impact, Carbon emissions.

Robust modeling of material flows to end‐uses under uncertainty: UK wood flows and material efficiency opportunities

AbstractIn this study we quantify wood flows from raw materials to end‐uses for the United Kingdom in a robust way using a new material flow analysis (MFA) model with uncertainty. This is important to identify opportunities for efficiency given constraints on wood supply. We have developed a new “ProbPACTOT” MFA model which introduces a systematic method to handle mixed units during reconciliation and uncertainty in data observations, conversion factors, and process recipes. This makes it possible to track material flows all the way to end‐uses, which is otherwise difficult because the diverse materials, data types, and units used to quantify end‐products are hard to integrate into standard allocation‐based MFA models. We apply the model for the case of wood in the United Kingdom by defining 56 process recipes and reconciling 117 data observations from various sources. The results quantify upstream production and trade flows, through to 19 specific end‐uses of wood fibers. We use this to show the potential scale of savings by enhancing material efficiency; for example, if pallets were used 25% more intensively, 0.49 0.2 of wood fibers could be saved, corresponding to 4%–7% of the total soft sawnwood consumption of the United Kingdom. Judging the scale of opportunities for wood material efficiency in the United Kingdom is important domestically, and has global significance as the United Kingdom is the second largest net importer of wood products in the world. Moreover, this study proposes an important advancement in MFA giving a structure for modeling uncertain material flows up to end‐uses, applicable to any material. This article met the requirements for a gold‐gold JIE data openness badge described at http://jie.click/badges.

Effects of technical advance on cobalt supply and its supply trends: A perspective of the whole industrial chains

By coupling dynamic material flow analysis and econometric models, the effects of technical advance on cobalt supply in the whole industrial chains are explored. Then, its supply trends are investigated at the global and national levels. The results show that: (1) the impact of technical advance on cobalt supply in the mining stage is inverted U-shape, while in the other stages, they are linear promotions. (2) Technical advance could increase global primary supply by up to 10 % from current production capacity. By 2030, secondary and total supplies will reach 79 kt and 251 kt or even more. (3) Refined cobalt supply share of China is expected to be 76 % by 2030. The European Union will produce the largest secondary supply, followed by China, the United States and Japan. (4) With the simultaneous development of technologies in each stage, supply-demand balance could be realized under some ideal scenarios. The above findings help intuitively recognize the roles of technical advance and strengthen the determination to do it.

Supporting zero-waste building: A novel spatial explicit material flow analysis model for construction waste

The accurate quantification of construction waste (CW) is prerequisite for achieving zero-waste in the building sector. This study employs a Spatial Material Flow Analysis model considering building life cycle to estimate the spatio-temporal dynamics of CW in Nanjing, China, over two decades. Additionally, it employs an ARIMA model for forecasting CW generation over the forthcoming decade. During 2000 to 2020, Nanjing's CW witnessed a CW increase from 0.8 to 59.0 Tg, predominantly comprising non-metallic materials. Meanwhile, the spatial distribution of CW has widened, accompanied by the emergence of numerous CW hotspots, in parallel with economic and population growth. Future projections suggest a continuous yet decelerating increase in CW generation, highlighting a significant opportunity for resource recovery. The application of this hybrid approach not only enhances CW management accuracy but also supports the broader goal of fostering sustainable building practices. This research expects to enlighten the stakeholders committed to advancing sustainable construction and waste management strategies in the context of zero-waste buildings.

Undoing the lock-in of suburban sprawl: Towards an integrated modelling of materials and emissions in buildings and vehicles

Suburban sprawl emerged during the 20th century alongside the widespread ownership of cars. This type of low-density housing generates enduring car dependency due to the long lifetimes of buildings. A more sustainable mobility system would require a deep transformation to densify urban forms and thus foster proximity of homes, work, and services. Here we explore the evolution of long-lived residential building stocks and the potential for breaking of this lock-in by selective demolishing of detached houses to densify urban forms. We assess impacts on land use, material demand and stocks, and greenhouse gas emissions. We use a novel dynamic, Material Flow Analysis (MFA) model applied to a Swedish case study that accounts for the co-relations of building stock and car fleets through residential density. The model includes different municipality types and we explore three different speeds for the change in urban form. An accelerated densification requires more bulk materials in construction but fewer scarcer materials in cars. However, the up-front emissions of accelerated densification construction are only compensated by mobility savings in the long-term, by 2100. Emissions trends for the three scenarios are far from the urgent decarbonisation necessary. However, the denser final built environments may have social benefits and can free up significant land.

An environmentally conscious waste management system in an effort to create a sustainable city (study of waste management systems at Syiah Kuala University)

Final Processing Site (TPA) is a place designated as a final stage waste management location. The increasing accumulation of waste can result in an increase in the volume and discharge of leachate generated through landfill management. Waste management can be implemented, one of which is supported by the existence of waste bank activities. Waste banking is a method implemented through the 3R concept (Reuse, Reduce and Recycle). This research aims to determine the waste management system at the Universitas Syiah Kuala Waste Bank, as well as supporting factors and strategies for increasing waste reduction. Improvements in waste bank management are analyzed using statistical tests, correlations and so on. The method used to determine whether waste bank management has improved is material flow analysis and structural equation modeling (SEM) testing. The results of the material flow analysis show that based on the mass balance the reduction potential of waste that can be managed by the Universitas Syiah Kuala Waste Bank is 45.4%. The results of statistical tests show that the waste management system at the Universitas Syiah Kuala waste bank, Banda Aceh is quite good, seen from the knowledge factor reaching 90.6%, attitude at 88.4% and waste bank behavior at 91.3%.

Computational Nanotoxicology Models for Environmental Risk Assessment of Engineered Nanomaterials.

Although engineered nanomaterials (ENMs) have tremendous potential to generate technological benefits in numerous sectors, uncertainty on the risks of ENMs for human health and the environment may impede the advancement of novel materials. Traditionally, the risks of ENMs can be evaluated by experimental methods such as environmental field monitoring and animal-based toxicity testing. However, it is time-consuming, expensive, and impractical to evaluate the risk of the increasingly large number of ENMs with the experimental methods. On the contrary, with the advancement of artificial intelligence and machine learning, in silico methods have recently received more attention in the risk assessment of ENMs. This review discusses the key progress of computational nanotoxicology models for assessing the risks of ENMs, including material flow analysis models, multimedia environmental models, physiologically based toxicokinetics models, quantitative nanostructure-activity relationships, and meta-analysis. Several challenges are identified and a perspective is provided regarding how the challenges can be addressed.

The potential of carbon storage in bio-based solutions to mitigate the climate impact of social housing development in Brazil

The increasing demand of housing in the Global South requires effective solutions to cover the corresponding deficit in the next decades. In Latin America, Brazil is the most populated Nation, which accounts for one-third of the total population and is the main contributor to carbon emissions. This study estimates how bio-based construction solutions, implemented in the Brazilian housing stock as alternative to conventional systems, can contribute to limiting the carbon emissions. Five different construction archetypes were considered, and a Material Flow Analysis model developed to estimate the demand of construction materials by 2050 under multiple scenarios. A carbon footprint assessment, which considers the dynamic effect of biogenic carbon sequestration and uptake, was finally performed to estimate the net Global Warming Potential. The results indicate that, if fast implemented, bio-concrete solutions with short-rotation vegetal species as bamboo, coupled with the lowest material intensity scenario, can reduce the cumulative carbon emissions by 65%, equal to 118 Mt of cumulative CO2-eq savings. Considering bamboo's widespread availability in Brazil's different climate zones, and in the Global South in general, such material presents a significant impact to mitigate the climate impact of social housing. However, the carbon saving intensity is largely affected by uncertainties on population growth and the type of biomass used in the concrete mixture. Therefore, further development of standards for the safe use of bio-concrete in construction is urgently needed, as well as the implementation of environmental policies to facilitate the market penetration of bio-based solutions in emerging economies.

The limitations of end-of-life copper recycling and its implications for the circular economy of metals

Increasing the recycling of metals reaching their end-of-life (EoL) is a vital circular economy approach to meet the growing demand for metals and reduce reliance on mining. To assess the potential of recycling strategies in fulfilling future metal demand and replacing primary production, we develop a novel dynamic probabilistic material flow analysis (MFA) model. Unlike previous MFA studies, our model explicitly explores the potential of recycling to reduce metal mining activities while considering uncertainties in future EoL collection and recycling rates. Focusing on copper, a critical mineral for low-carbon technologies, the model dynamically estimates the future copper stocks and flows under three different demand scenarios and probabilistic EoL collection and recycling assumptions. Our analysis reveals that the share of EoL secondary supply of overall copper demand, which currently stands at 23 %, will even under the scenario with the lowest future copper demand only be averaging 33.4 % over the next three decades. In addition, even under the most optimistic circumstances with lower than expected copper demand and very high collection and recycling rate growth, the annual share of EoL secondary supply of overall copper demand would only reach 49.6 % in 2050. Thus, primary copper extraction is expected to rise significantly until at least 2040 and under 87 % of all 30,000 modelled outcomes, primary production of copper in 2050 will still be above 2020 production levels. Consequently, we emphasise the need for alternative circular economy strategies beyond recycling, such as demand reduction and mitigating the harmful impacts of primary metal production.

The material implications and embodied emissions of clean power transition in Guangdong, China from 1978 to 2050

The national and regional carbon neutrality ambition necessitates clean power transition but also requires significant amount of generation, transmission, and storage infrastructure for renewables. Understanding the consequent material implications and embodied emissions of such energy infrastructure development with a system perspective at various geographical scales is thus important for maximizing emissions reduction and minimizing trade-offs among climate, resource, and waste targets. Previous research along this line, however, often focuses on individual subsystems (e.g., power generation) or individual technologies (e.g., wind energy) on a global or national scale. Here, we combined a dynamic material flow analysis model, life cycle assessment database, and scenario analysis to characterize stocks, flows, and embodied emissions of six bulk materials and thirteen critical materials associated with clean power transition from 1978 to 2050 in Guangdong province, China. We show that Guangdong's clean power transition leads to a total material stock increase from 2.9 Mt in 1980 to 45.6 Mt in 2018 and further to 95.7 Mt in 2050 under the basic renewable energy scenario (BES). The material stock in both generation and storage subsystems will grow over time, whereas that in the transmission subsystem will peak at approximately 2040 and then gradually decline. The massive expansion of wind and nuclear energy will result in a drastic rise in materials use, especially for cement and steel. A higher proportion of renewables increases energy infrastructure embodied emissions but reduces overall emissions. Future mitigation efforts and policy should not only address operational emissions through energy structure adjustment, but also curb the embodied emissions through infrastructure lifetime extension, material efficiency improvement, and material production decarbonization.

Advancing sustainability in China's pulp and paper industry requires coordinated raw material supply and waste paper management

As the largest global producer and consumer of pulp and paper, China faces significant sustainability challenges in fiber supply and waste paper management. A comprehensive material flow analysis of China's pulp and paper industry (CPPI) is needed to understand the interaction between raw material supply and waste paper management. Here, we construct a closed-loop material flow analysis model for CPPI, examine the evolution patterns of material metabolism from 1990 to 2019, and explore the demand for paper production, waste paper recycling, and virgin fiber supply in 2030 and 2050 under multiple scenarios considering critical factors. Results show that the industry has undergone rapid expansion, increased material use efficiency, and a shift towards recycled pulp from 1990 to 2019. China's paper demand will grow to 186 Mt in the next 30 years, resulting in a significant increase in both demand for fibers (173 Mt) and the generation of waste paper (138 Mt). To ensure a sustainable fiber supply for CPPI, domestic waste paper recycling needs to be prioritized. However, attention should also be paid to the availability of virgin pulp supply and proper disposal of organic solid waste. Proper management of these factors is crucial for achieving a circular economy in the industry and reducing its environmental impact. The findings highlight the importance of addressing both raw material supply and waste paper management for CPPI's sustainable development.

Greenhouse gas emissions associated with plastics in China from 1950 to 2060

The unprecedented rise of plastics has caused substantial greenhouse gas (GHG) emissions. In this study, material flow analysis and GHG accounting models were integrated to estimate the GHG emissions of plastics in China from 1950 to 2020, and the dynamic evolution from 2021 to 2060 was tracked. The cumulative GHG emissions were 5544.0 Mt CO2eq from 1950 to 2020, and 496.8 Mt CO2eq of GHG were emitted in 2020. Monomer production stage had the highest GHG emissions (58.6%) and electricity consumption was the major emission source (69.0%). GHG emissions of baseline and comprehensive scenarios would reach a peak in 2040 and 2030, respectively. Neutral scenario was the only scenario that achieved carbon neutrality by 2060. GHG emission reduction requires reducing plastic demand, improving waste recycling, and adopting bio-based plastics and renewable energy. This study scientifically explored the path of carbon peak and carbon neutrality to combat climate change.

Material flow analysis-based assessment of polypropylene-fiber-containing microplastics released from disposable masks: Characterizing distribution in the environmental media

With the upsurge in the use of disposable masks during the coronavirus disease pandemic, improper disposal of discarded masks and their negative impact on the environment have emerged as major issues. Improperly disposed of masks release various pollutants, particularly microplastic (MP) fibers, which can harm both terrestrial and aquatic ecosystems by interfering with the nutrient cycling, plant growth, and the health and reproductive success of organisms. This study assesses the environmental distribution of polypropylene (PP)-containing MPs, generated from disposable masks, using material flow analysis (MFA). The system flowchart is designed based on the processing efficiency of various compartments in the MFA model. The highest amount of MPs (99.7 %) is found in the landfill and soil compartments. A scenario analysis reveals that waste incineration significantly reduces the amount of MP transferred to landfills. Therefore, considering cogeneration and gradually increasing the incineration treatment rate are crucial to manage the processing load of waste incineration plants and minimize the negative impact of MPs on the environment. The findings provide insights into the potential environmental exposure associated with the improper disposal of waste masks and indicate strategies for sustainable mask disposal and management.

Thermodynamical Material Networks for Modeling, Planning, and Control of Circular Material Flows

ABSTRACT Material flow analysis (MFA) is the main methodology to assess material flow circularity. It is essentially a data-analysis-based approach whose physical foundations consist of conservation of mass. To improve both the accuracy and the repeatability of MFA models, in this paper we leverage compartmental dynamical thermodynamics merged with graph theory and control theory. The key idea is that the thermodynamic compartments and their connections can be added, removed or modified as needed to achieve a circular material flow. Thus, our methodology consists of designing thermodynamical material networks (TMNs). We also provide a physics-based definition of circularity and implement a nonlinear compartmental control, which has been possible since TMNs are highly dynamic models based on differential calculus (i.e. ordinary differential equations) rather than on arithmetic as is typical for MFA models. As we envision scalable and repeatable designs of TMNs, we made publicly available the paper source code. 1