This contribution presents the state of the art of economy-wide material flow accounting. Starting from a brief recollection of the intellectual and policy history of this approach, we outline system ...definition, key methodological assumptions, and derived indicators. The next section makes an effort to establish data reliability and uncertainty for a number of existing multinational (European and global) material flow accounting (MFA) data compilations and discusses sources of inconsistencies and variations for some indicators and trends. The results show that the methodology has reached a certain maturity: Coefficients of variation between databases lie in the range of 10% to 20%, and correlations between databases across countries amount to an average R2 of 0.95. After discussing some of the research frontiers for further methodological development, we conclude that the material flow accounting framework and the data generated have reached a maturity that warrants material flow indicators to complement traditional economic and demographic information in providing a sound basis for discussing national and international policies for sustainable resource use.
Summary
This contribution presents the state of the art of economy‐wide material flow accounting. Starting from a brief recollection of the intellectual and policy history of this approach, we ...outline system definition, key methodological assumptions, and derived indicators. The next section makes an effort to establish data reliability and uncertainty for a number of existing multinational (European and global) material flow accounting (MFA) data compilations and discusses sources of inconsistencies and variations for some indicators and trends. The results show that the methodology has reached a certain maturity: Coefficients of variation between databases lie in the range of 10% to 20%, and correlations between databases across countries amount to an average R2 of 0.95. After discussing some of the research frontiers for further methodological development, we conclude that the material flow accounting framework and the data generated have reached a maturity that warrants material flow indicators to complement traditional economic and demographic information in providing a sound basis for discussing national and international policies for sustainable resource use.
The resilience and low cost of plastics has made their usage ubiquitous, but is also the cause of their prevalence and longevity as waste. Plastic pollution has become a great concern to the health ...and wellbeing of ecosystems around the world; microplastics are a particular threat, due to their high mobility, ease of ingestion by wildlife, and ability to adsorb and carry toxic contaminants. Material flow analysis has been widely applied to examine stocks and flows of materials in other industries, and has more recently been applied to plastics to examine areas where waste can reach the environment. However, while much research has gone into the environmental fate of microplastics, degradation strategies have been a lesser focus, and material flow analysis of microplastics has suffered from lack of data. Furthermore, the variety of plastics, their additives, and any contaminants pose a significant challenge in degrading (and not merely fragmenting) microplastic particles. This review discusses the current degradation strategies and solutions for dealing with existing and newly-generated microplastic waste along with examining the status of microplastics-based material flow analysis, which are critical for evaluating the possibility of incorporating microplastic waste into a circular economy. The degradation strategies are critically examined, identifying challenges and current trends, as well as important considerations that are frequently under-reported. An emphasis is placed on identifying missing data or information in both material flow analysis and degradation methods that could prove crucial in improving understanding of microplastic flows, as well as optimizing degradation strategies and minimizing any negative environmental impact.
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•Microplastic remediation is trending towards sustainable options.•Challenges arise from variety of plastics, additives, and contaminants.•Completeness of degradation is important, but not often investigated.•Additional reporting of parameters and characterization is needed.•Degradation techniques could be combined to address their respective disadvantages.
Assessing progress towards environmental sustainability requires a robust and systematic knowledge base. Economy-wide material flow accounting (ew-MFA) is an established method to monitor resource ...use across scales and its headline indicators are widely used in policy. However, ew-MFA is currently limited by its empirical focus on annual flows of material and energy, because it neglects the pivotal role of in-use material stocks of manufactured capital. Explicitly integrating in-use stocks enables new insights into a range of Ecological Economics' topics, such as the biophysical assessment of socio-economic systems, the circular economy and stock-flow consistent scenarios.
Herein, we conceptually and practically expand the ew-MFA framework towards jointly addressing material flows, in-use stocks of manufactured capital and waste, using a fully consistent dynamic model of Material Inputs, Stocks and Outputs (MISO-model). We review the stock modelling literature, propose a novel distinction of stock-driven versus inflow-driven approaches and situate the MISO-model as the latter. We then investigate the global dynamics of socio-metabolic flows and in-use stocks from 1900 to 2014, explore model sensitivities and quantify and attribute uncertainty. Two exemplary scenarios are presented. Through these innovations for ew-MFA, we enable a dynamic and comprehensive assessment of resource use, stocks and all wastes in the socio-economic metabolism.
•Use-phase, in-use stock dynamics, waste and recycling crucial next steps for ew-MFA•Review of stock-modelling yields new classification: stock-driven vs. inflow-driven•Dynamic inflow-driven model of Material Inputs, Stocks and Outputs (MISO-model v1)•Global in-use stocks increase 26-fold to 928 Gt ± 5% between 1900 and 2014•Two exemplary scenarios on the importance of stock dynamics are shown
•The demand for aluminium is forecasted on an alloy-level per industrial sector.•A global aluminium scrap surplus of 5.4 million tonnes/year is forecasted in 2030.•Wrought-to-wrought recycling is ...essential to mitigate the growth of the scrap surplus.•A sampling campaign is undertaken to experimentally verify the literature data.•The evolution of the scrap surplus is sensitive to trends in the automotive industry.
The probable emergence of a global aluminium scrap surplus in the coming decade is one of the main incentives for the aluminium recycling industry to invest in new methods and technologies to collect, sort and recycle aluminium scrap. However, due to the considerable uncertainty in the evolution of the global scrap surplus, it is difficult for policymakers and the recycling industry to accurately estimate the economic and environmental advantages of implementing enhanced sorting and recycling methods. The International Aluminium Institute (IAI) has developed a model to track and forecast the global flows of aluminium, but this model is not extensive enough to estimate the scrap surplus evolution. Therefore, this paper introduces an alloy series resolution to the supply and demand of aluminium in the IAI’s global flow model and estimates the composition of the recovered scrap flows to improve the estimate of the technical potential of secondary alloy production. The estimated scrap surplus evolution is subjected to a sensitivity analysis, considering the most critical parameters, including the speed of electrification in the automotive sector, the recovered scrap’s composition and the lifetime of aluminium products. In addition, the estimated composition of the recovered aluminium scrap in the model is compared to composition measurements of alumimium scrap collected at a Belgian recycling facility as a means of validation. This study allows to estimate that the global aluminium scrap surplus will emerge soon and reach a size of 5.4 million tonnes by 2030 and 8.7 million tonnes by 2040, if currently adopted aluminium sorting and recycling methods are not improved.
With the rapid development of new infrastructure in China, the demand for copper has increased significantly. In 2021, copper consumption in this sector accounted for 9.1% of China's total ...consumption, becoming a new driving force for copper demand. This study analyzed copper flow characteristics and primary driving factors in China's new infrastructure sectors using the material flow analysis method, quantified the environmental loads of the metabolic processes, and predicted copper demand in the new infrastructure sectors by 2030 through scenario analysis. The primary conclusions drawn are as follows: In 2021, copper consumption in new infrastructure sectors was 1,225,700 tons, with the rail transportation sector accounting for 59.6% and the artificial intelligence sector accounting for 0.6%. The rail transportation sector had the largest total environmental load, with carbon emissions of approximately 3,513,372 tons. From the perspective of tons of copper products, the 5G sector had the highest environmental load, while the big data centers had the lowest. In the seven sectors of new infrastructure, the environmental load contribution rates across the four stages showed little variation, with their proportions being 49.0, 29.8, 15.8, and 5.4%, respectively. Recycling of discarded copper products can effectively reduce industrial energy consumption and carbon emissions. Under the three scenarios set in this study, the copper demand in the new infrastructure sector by 2030 will be 3.856, 3.233, and 2.625 million tons, respectively. Using wind energy to replace coal in copper production can reduce carbon emissions by approximately 43.2%.
•Rapid new infrastructural development drives rapid growth in copper consumption.•Quantified the environmental impact of copper usage in new infrastructure field through lifecycle assessment methods.•Copper demand in new infrastructure field projected to increase significantly by 2030.•Replacing 50% coal in copper production with wind energy can reduce CO2 emissions.
•A review of material and energy flows in the iron and steel industry is provided.•Material scheduling and energy saving technologies for steelworks are reviewed.•Forecasting and optimization models ...of material and energy flows are introduced.•Challenges of current studies on material and energy flows are identified.•Future directions of material flow and energy flow research are discussed.
Integrated analysis and optimization of material and energy flows in the iron and steel industry have drawn considerable interest from steelmakers, energy engineers, policymakers, financial firms, and academic researchers. Numerous publications in this area have identified their great potential to bring significant benefits and innovation. Although much technical work has been done to analyze and optimize material and energy flows, there is a lack of overview of material and energy flows of the iron and steel industry. To fill this gap, this work first provides an overview of different steel production routes. Next, the modelling, scheduling and interrelation regarding material and energy flows in the iron and steel industry are presented by thoroughly reviewing the existing literature. This study selects eighty publications on the material and energy flows of steelworks, from which a map of the potential of integrating material and energy flows for iron and steel sites is constructed. The paper discusses the challenges to be overcome and the future directions of material and energy flow research in the iron and steel industry, including the fundamental understandings of flow mechanisms, the dynamic material and energy flow scheduling and optimization, the synergy between material and energy flows, flexible production processes and flexible energy systems, smart steel manufacturing and smart energy systems, and revolutionary steelmaking routes and technologies.
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•A trade-linked MFA model is applied to map the global and regional gallium cycles.•The majority of gallium from global bauxite mining ended up as gallium losses.•The global in-use ...stock increased rapidly, indicating a potential recycling source.•China has emerged as the largest global gallium resource supplier since 2005.
Byproduct metals are essential to global low carbon transition since they are irreplaceable in modern renewable energy technologies. Gallium (Ga) is classified as one critical byproduct metal due to its extensive use in electronic applications and low carbon technologies, as well as its limited resource endowment. It is urgent to uncover the global and regional Ga stocks and flows so that the potential supply risks can be mitigated. This study maps the global and regional Ga cycles for the period of 2000–2020 by employing a trade-linked multiregional material flow analysis (MFA) method. Our results show that 79% of the global Ga co-mined from bauxite ended up in red mud or entered the aluminum cycle as an impurity, indicating a significant recycling potential. Different involved regions have different but complementary roles in the global Ga supply chain. China dominates the global primary Ga production, accounting for 97% of the global total in 2020. Japan and the United States are key players in high-purity Ga refining and rely on Ga to support their electronic devices manufacturing. Unfortunately, Ga recycling practices are still not occurring due to the low Ga concentrations in major applications. Since the global demand for Ga will continue to grow in the near future, it is urgent to initiate collaborative efforts so that Ga recycling can be enhanced. These efforts are critical to ensure the sustainable Ga supply and facilitate the global transition toward low carbon development.
•A novel simulation method of FSW based on two-phase flow is proposed.•High-velocity rotating flow zone is the channel for vertical migration of material.•The accuracy of the simulation results is ...verified by experimental measurement.
In this letter, combined experimental and computational analysis has allowed new understanding of the vertical material flow behaviors during friction stir welding. It is found that a high-velocity rotating flow zone exists near the welding tool, where horizontal and vertical flow are both significant. Material entering the high-velocity rotating flow zone migrates to the lower location of the workpiece after multiple rotations. Material outside the high-velocity rotating flow zone bypasses the tool and migrates towards the upper locations. The findings of this research offer insights into the regulation of microstructures and the formation of defects in FSW.
China's high copper demands and poor mineral endowments have led it to rely heavily on the international copper trade. However, the importance of the metal trade has not been adequately appreciated. ...This study explores the role of metal trade in copper security through a high-resolution material flow analysis of China's copper cycle from 1950 to 2015 that covers over 300 types of copper-containing products. We found that the annual inflow of copper has increased from 4.3 KT/yr to 14 MMT/yr from 1950 to 2015, which drove the increase of copper stocks accumulated in buildings, infrastructures, and products from 7 kg/cap to 56 kg/cap. The total copper in-use stocks in China were approximately 80 MMT in 2015. However, about 70% of all copper used in China in this period was imported from other nations. Thus, this study indicates that more attention should be paid to the importance of the copper waste trade in China.
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