Dynamic Material Flow Analysis Research Articles

Mining the in-use stock of energy-transition materials for closed-loop e-mobility

The decarbonization of transportation is essential to achieve a carbon neutral planetary society. However, the turn to electromobility is based on advanced technologies (e.g., lithium-ions batteries) that tied our development to many functional materials with problematic supply. In this study, we apply prospective dynamic material flow analysis to explore the potentials for closing material cycles while meeting a full transition to electric for a set of energy-transition materials (ETMs) including lithium, cobalt, nickel, manganese, and natural graphite. Three demand scenarios are applied to develop trajectories for ETM demand, their in-use stock, and derive the potentials to which recycling can substitute for virgin material extraction at the global scale to 2065.Our results estimate that ETM inflow to use could increase between 20 and 50 times by 2065. However, secondary supply will hardly enable the achievement of circularity in material cycles in the next decades so that the supply of ETMs will remain mainly based on primary material extraction. Nevertheless, from 2040 onwards, recycling volumes could meet up to more than 80% of demand and represent a viable alternative to mining. If the ideal scenario is realized, government policies could have the potential for achieving the dual goal of decarbonizing e-mobility and securing sustainable access to ETMs already in the middle of 2050s. However, the combined commitment and efforts across the value chain of policymakers, companies involved in the cycle, and consumers will be needed to fully realize the great potential for circular economy to work for e-mobility.

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.

Eco-efficiency evaluation and simulation optimization of multi-life cycle recycling of lead: Evidence from China

Multi-life cycle (MLC) recycling of lead is an effective way to achieve the sustainable development of the lead industry, but the comprehensive effect of resource utilization and environmental impact in the process is difficult to evaluate. Eco-efficiency is a comprehensive indicator that takes into account resources and environment and can be effectively applied to the evaluation of the MLC recycling of lead. Therefore, this study aimed to develops modified stock-based model and dynamic material flow analysis to quantify the MLC recycling structure of lead, and then constructs an eco-efficiency evaluation system combined with life cycle assessment. The MLC recycling of lead was found to no longer allow China mine primary lead in 2041. During 2000–2050, the MLC recycling increased both the resource cumulative effect by 11.13 times and the eco-efficiency measured via the indicator of global warming potential by 2.55 times. We construct three policy scenarios: enhancing recycling technology, massive replacement and improving environmental regulation. The combined policy of all the scenarios exerted the best promotion effect on the recycling structure, resource cumulative effect, and eco-efficiency. Improving the lead production technology and seeking a win-win situation between lead-acid and lithium batteries were the key to achieving the sustainable development of the lead industry.

Combining dynamic material flow analysis and life cycle assessment to evaluate environmental benefits of recycling – A case study for direct and hydrometallurgical closed-loop recycling of electric vehicle battery systems

We conduct a life cycle assessment (LCA) for two recycling processes, a hydrometallurgical and a direct recycling route. Both show ecological benefits compared to production with virgin material (between 2.76–4.55 kg CO2e/ kg battery for NMC111 and NMC811 less greenhouse gas emissions). In contrast to previous works, we combine the LCA results with a dynamic material flow model. This allows the evaluation of the influence on ecological benefits of admixture limits for directly recycled cathode material in a closed-loop recycling system over a time in which the newly produced battery systems and the amount of end-of-life traction batteries grows. We show that for such a closed-loop recycling system, the choice of different allocation methods, namely cut-off or avoided burden approach, may lead to significantly varying results of up to 85% in ecological benefits. We further conclude that combining production with both recycling routes can achieve the lowest greenhouse gas emissions for our closed-loop scenarios.

Material Requirements, Circularity Potential and Embodied Emissions Associated with Wind Energy

Wind energy, which is often posited as a key decarbonisation option, represents one of the fastest-growing energy sources globally in recent years. Research on the material requirements for transitioning to a low-carbon electricity system at national levels, as well as research exploring the potential of the electricity system to serve as a source of secondary materials remains underexplored. We address these gaps in the knowledge by analysing the stocks and flows in a wind power system towards 2050 using Sweden as a case study, including the demands for bulk (concrete and steel) and critical materials (neodymium and dysprosium), through a dynamic material flow analysis based on policy-relevant scenarios. We demonstrate that some of the investigated scenarios generate substantial increases in the stocks and flows of bulk and critical materials. We show that, after 2045, the year by which Sweden has committed to reducing greenhouse gas emissions to net-zero, the inflows show a decreasing trend while the outflows show an increasing trend, suggesting the beginning of the closing of the material loops, provided untapped circularity potentials transform into actual capacities. For wind power to comply with emissions targets, the steel and concrete production processes will need to be decarbonised at a rate in line with the climate targets. We show that the adoption of mitigation measures to decarbonise the concrete and steel industries aligned with Sweden's climate change mitigation agenda, has the potential to reduce embodied carbon emissions for wind power infrastructure in 2045 from corresponding to around 4 % of current total national emissions in the absence of measures to practically negligible levels. National policies need to focus on promoting the implementation of circularity strategies and decarbonising the entire value chain of the involved materials.

Assessing the energy efficiency potential of a closed-loop supply chain for household durable metal products in China

The dramatic increase in Chinese residents’ income has driven a sharp increase in the purchase of household durable metal products (HDMPs), which are classified into automobiles and other durable products, mainly appliances and electronics. To explore the energy efficiency potential of the closed-loop supply chain (CLSC) for the HDMP industry in China, we develop a comprehensive evaluation framework based on dynamic material flow analysis and life cycle assessment. The results show that the demand for appliances and electronics and for electric cars will reach peaks in 2028 and 2035, respectively, and annual scrap for appliances and electronics and for electric cars will reach peaks in approximately 2036 and 2040, respectively. The recycling of scrap iron, aluminium, and copper can achieve energy conservation of approximately 72%, 94%, and 82%, respectively, compared with metal primary production, while remanufacturing processes can further reduce energy consumption by approximately 68%, 57%, and 72%, respectively. If the energy consumption of metal production, recycling rate, and remanufacturing rate can reach internationally advanced levels by 2035, approximately 50.5 Mtce (million-ton coal equivalent) will be saved compared to low-speed development by 2050; among these factors, the regeneration of waste metals can achieve the most significant energy efficiency effect.

Battery as a service: Analysing multiple reuse and recycling loops

This study investigates the effects on new product demand and raw materials from the growth of a company's product-service system (PSS), using dynamic material flow analysis. The PSS involves multiple reuse and recycling of lithium-ion battery subpacks for mining equipment. While effects differ over time, 13% of new subpacks and 13–59% of primary material demand is reduced within the PSS until 2050. Supply of subpacks for reuse surpasses demand, limiting displacement of new subpacks. Reuse increases battery self-sufficiency and has limited effects on primary material demand when recycling is efficient, but more so when recycling is less efficient. Thus, if efficient recycling is unachievable, reuse becomes more important for raw material self-sufficiency in the PSS. Reusing batteries could lead to European recycled content targets not being reached in time. Thus, such targets are challenging to balance with policy goals for reuse and pose risks for companies relying on extensive reuse.

Tracing magnesium flows in China: A dynamic material flow analysis

Magnesium is a unique and widely-applied alkaline earth metal. China is the major magnesium producer and exporter, but the key features of its magnesium flows, such as the total production, the structure of demand, the efficiency of utilization, the volume of recycling, remain unclear. This study aims to investigate magnesium metabolism in China from 2002 to 2021 by employing a retrospective, dynamic material flow analysis method. Results show that (1) China's magnesium supply has doubled to meet its tripled demand during the last 20 years; (2) more than 69% of the magnesium produced in China was used for making refractory materials, while the pure magnesium application accounted for less than 5%; (3) the total net magnesium export reached 1.8 megatons (Mt) in 2021; (4) 1.4 Mt of magnesium was recycled during the study period, only accounting for 9.8% of the total primary magnesium production. Finally, policy recommendations are proposed by considering the Chinese realities, including improving resource efficiency, incubating efficient production technologies, increasing added values of magnesium-containing products, and optimizing trading for magnesium-containing products.

Mapping Provincial Stocks and Wastes of Passenger-Vehicle Plastics in China Based on Dynamic Material Flow Analysis and GIS: 1985–2019

As a polymer material, plastic is widely used in passenger vehicles for its light weight and low-cost advantages. China has accumulated a large amount of discarded automotive plastic in recent years, which has put increasing pressure on the environment and the recycling industry. A dynamic material flow model for estimating the plastic stock and waste in passenger vehicles was developed. Additionally, geospatial models were used to study the spatiotemporal evolution trend of passenger vehicle plastics. The results show: (1) passenger-vehicle plastic stock and waste in China increased rapidly from 1985 to 2019. By 2019, the passenger-vehicle plastic stock was 36.94 million tons, and the waste amount was 1.64 million tons, of which polypropylene accounted for the greatest proportion, and polyoxymethylene (POM) accounted for the least. (2) The stock and waste of passenger-vehicle plastics showed spatial dependency. (3) The spatial center of plastic waste was located in Henan Province, and the spatial center is shifting from north to south. (4) The GDP and the annual population are the main driving factors of passenger-vehicle plastic waste. This study will improve plastic waste management, resource recovery, and environmental sustainability decisions.

Uncovering the key features of gold flows and stocks in China

Gold is an important strategic mineral resource in China, mainly used in jewelry, investment, catalysts, emerging industries, and other fields. With the influence of increased geopolitical risks, energy crisis, housing costs, food prices and other factors, global inflation is becoming increasingly severe. As one of the best performing assets addressing stagflation, the price of gold continues to rise. This study aims to investigate gold metabolism in China from 2001 to 2020 by employing dynamic material flow analysis. The results show that China's gold consumption gradually increased, in which the jewelry sector had the largest gold consumption, while the gold coin and several industrial sectors also increased their gold consumptions. Also, the domestic gold production cannot meet its future gold demand, and the domestic gold recycling is still immature. Based on these research findings, policy recommendations for sustainable gold resource management are proposed, including the optimization of gold trade structure, the development of gold recycling network.

Insights into the evolution of cobalt use and implications through dynamic analysis of cobalt flows and stocks and the recycling potential of cobalt from urban mines in China during 2000–2021

Several countries regard cobalt as a critical material due to its extensive use in clean energy technology and high-tech industries. To comprehensively examine how China’s cobalt industry developed and evolved from 2000 to 2021, our study quantified cobalt flows, stocks and the recycling potential of cobalt from China’s urban cobalt mines using dynamic material flow analysis. In 2021, China’s in-use cobalt stocks for cobalt-containing end products reached 131 kt, of which battery products and superalloys accounted for 83.8% and 8.1%, respectively. The theoretical cumulative recycling potential of cobalt from China’s urban cobalt mines reached 204–356 kt between 2000 and 2021 under different scenarios. However, the actual cumulative exploitation of cobalt from urban cobalt mines was 46–80 kt, of which consumer electronics, cemented carbides, and superalloys were the main recycled products. The cumulative exports and imports of cobalt in all commodities reached 558 and 1117 kt, respectively. China exported a large quantity of cobalt chemicals, chemical derivatives and cobalt-containing end products produced from imported cobalt raw materials. China imported 84.7% of the cobalt raw materials consumed domestically, and 32.6% of the domestically produced cobalt-containing end products were exported. Over the entire life cycle of cobalt, cobalt losses totaled 288 kt, with 51.0% of losses coming from refining, and a 73.8% cobalt utilization efficiency was achieved. China recovered 76.7 kt of cobalt, and the recycling rate of cobalt from end-of-life cobalt-containing end products reached 20.0%. The findings can serve as a scientific basis for China’s cobalt industry to develop efficiently and economically.

Dynamic Plastics Flow Analysis for Korea between 1982-2020

Objectives : This study analyzed Korea’s plastic flows and stocks over the past 40 years to provide a quantitative basis for the nation’s plastic management and circular economy.Methods : Dynamic material flow analysis was conducted to quantify plastic flows across lifecycle stages and to estimate the size of in-use stocks. Focusing on 10 resins and 7 products, the analysis was conducted between 1982 and 2020 and at a national level. Production and trade flows were mainly quantified based on statistical and literature data, while consumption and waste flows were estimated using transfer coefficients. Different from static material flow analysis, waste flows were calculated based on the products’ lifetime distribution functions, and the changes in in-use stocks were estimated.Results and Discussion : Between 1982 and 2020, Korea produced 237 million tons of resins and provided 242 million tons of primary plastic products after the trade. Approximately 207 million tons of final products were consumed, 71% of which was generated as post-consumption waste and additional 3.8 million tons of waste was generated from the manufacturing stage. The amount of in-use stock of plastics was estimated to be 60 million tons. Of the 151 million tons of plastic waste, 24% was landfilled, 29% was incinerated and 47% was entered into sorting and recycling facilities. After sorting and recycling, 27 million tons were estimated to be recycled into products. From 1982 to 2020, per-capita plastic consumption increased from 15 kg to 150 kg, and per-capita waste generation increased from 2 kg to 139 kg. Packaging and containers, or PP and PE represented a major share of plastic consumption as well as waste generation. On the other hand, about half of the plastic stock was used for buildings and more than 50% of the building plastic stock was PVC.Conclusion : This study used a dynamic material flow analysis to quantify plastic flows over time, identify the composition of plastic waste flows according to resins or products, and estimate the size of in-use stocks. Such information on the waste composition and in-use stocks would be useful to improve recycling systems and estimate future waste flows.

The slow-release effect of recycling on rapid demand growth of critical metals from EV batteries up to 2050: Evidence from China

In the severe situation of global warming, the low-carbon transition in the transportation sector requires critical metals, which have been in considerable demand in China, posing serious challenges to sustainable supply of resources. Using dynamic material flow analysis model, this study predicted the demand for critical metals used in lithium-ion batteries (LIBs) for electric vehicles (EVs) in China by capturing factors of two dimensions like EV market size and LIB technology path, and then assessed the slow-release effect of recycling on critical metal demand from 2010 to 2050 in seven selected scenarios. The results showed that the contradiction among metal demand, reserves, and production brought about by the development of EVs is very severe. Cobalt depletion can be addressed by switching to low-cobalt or cobalt-free LIB technology paths, which could lead to a much larger increase in nickel demand. Under different scenarios, the effect of recycling on metal demand would be different in the short and long term.

What to Do about Plastics? Lessons from a Study of United Kingdom Plastics Flows.

Plastics are one of the most widely used materials on the planet, owing to their usefulness, durability, and relatively low cost. Yet, making, using, and disposing of plastics create important environmental impacts, most notably greenhouse gas emissions and waste pollution. Reducing these impacts while still enjoying the benefits of plastic use requires an integrated assessment of all of the life cycles of plastics. This has rarely been attempted due to the wide variety of polymers and the lack of knowledge on the final uses and applications of plastics. Using trade statistics for 464 product codes, we have mapped the flows of the 11 most widely used polymers from production into six end-use applications for the United Kingdom (UK) in 2017. With a dynamic material flow analysis, we have anticipated demand and waste generation until 2050. We found that the demand for plastics seems to have saturated in the UK, with an annual demand of 6 Mt, responsible for approximately 26 Mt CO2e/a. Owing to a limited recycling capacity in the UK, only 12% of UK plastic waste is recycled domestically, leading to 21% of the waste being exported, labeled as recycling, but mostly to countries with poor practices of waste management. Increasing recycling capacity in the UK could both reduce GHG emissions and prevent waste pollution. This intervention should be complemented with improved practices in the production of primary plastics, which currently accounts for 80% of UK plastic emissions.

Material Flow Analysis in WEEE Management for Circular Economy: A Content Review on Applications, Limitations, and Future Outlook

Recently, the material flow analysis (MFA) of waste from electrical and electronic equipment (WEEE) has attracted much interest from researchers worldwide because of its function as a decision-making tool for moving towards a circular economy and sustainability in WEEE management. However, review studies on the development of MFA in WEEE management studies are still lacking. To fill this gap, 115 MFA studies published in various databases between 2010 and 2022 were analysed to provide a comprehensive overview of current research progress and recommendations for future studies. Three major elements from previous studies were reviewed using content analysis: (i) the trend of publishing in OECD and non-OECD countries over time; (ii) the scope and boundaries of the aspect studied, and the use of MFA in forecasting the generation, flow, and stock of WEEE; and (iii) providing a future outlook for MFA studies based on its limitations. Further analysis has revealed a considerable increase in the number of studies on MFA of WEEE in major OECD nations; however, the number of studies on concentrated areas of WEEE, particularly in non-OECD countries, remains low. Another limitation of MFA research is the scope and boundaries, with very few studies addressing the aspects of uncertainty analysis, circular economy, and life cycle analysis. Due to the increasing number of newly developed methodologies and the absence of thorough evaluation on this study topic, few studies properly utilised the static or dynamic MFA model. Thus, based on the research limitations and gaps discussed, recommendations for future studies are proposed.

A review of methods to trace material flows into final products in dynamic material flow analysis: Comparative application of six methods to the United States and EXIOBASE3 regions, Part 2

Modeling pathways toward sustainable production and consumption requires improved spatio-temporal and material coverage of end-use product stocks. Momentarily, studies on inflow-driven, dynamic material flow analysis (dMFA) extrapolate scarce information on material end-use shares (i.e., ratios that split economy-wide material consumption to different end-use products) for single countries and years across longer time periods and global regions. Therefore, in part 1 of this work, we reviewed five methods to derive material end-use shares which use industry shipment data in physical units and monetary input–output tables (MIOTs). Herein, we comparatively apply these methods to the United States, drawing on detailed national data, as well as the multi-regional input–output model EXIOBASE3. To better match MIOT and dMFA system definitions, we propose the end-use transfer method, which re-routes specific intermediate outputs to final demand in MIOTs. In closing, we conclude on 12 points for improved end-use shares. We find mixed results regarding the fit between end-use shares derived from industry shipments and MIOTs: for detailed national data, we find good fit for some materials (e.g., aluminum), while others deviate strongly (e.g., steel). In many cases, the temporal trend of MIOT-derived end-use shares roughly agrees with industry shipments. For EXIOBASE3, we find good fit for some countries and materials, but substantial mismatches for others. Despite mixed results, combining MIOT-based end-use shares with industry shipments and auxiliary country-level data could enable improved temporal, geographical, and end-use resolution. However, the scarcity, documentation, and quality of input data are key limitations for more accurate and detailed end-use shares. This article met the requirements for a gold-gold data openness badge described at http://jie.click/badges.

Dynamic material flow analysis of Chinese ethylene production processes and optimal pathway exploration with potential environmental-economic impacts

China is expected to become the largest ethylene producer globally; environmental problems related with traditional ethylene production process of Chinese petrochemical industry will be further stern. This study aims to propose a feasible and optimal ethylene production expansion pathway to improve the trade-off between the environment and economy. A novel approach was adopted with material-energy-value flow analysis integration by combining dynamic scenario analysis. According to the results of scenario analysis, cleaner and lightweight production processes optimization achieved by adopting the alternative ethylene production process mix alleviated environmental pressure and achieved a weak decoupling of the low-carbon economy. A 26.1% increase in carbon productivity was achieved compared with the baseline scenario, whereas the coal to ethylene route should be phased-out, as more than 90% of the pollutants are generated by 10%–17% of the coal to ethylene facilities. However, CO2 emissions from ethylene will inevitably increase along with doubling ethylene production. An imbalance in pollutant generation also emerges if large-scale naphtha is exclusively promoted for ethylene plant implementation. The study provides methodological support for investigating feasible roadmaps for key product capacity expansion, and has practical meaning for high-quality industrial development domestically and globally.

A first comprehensive estimate of electronic waste in Canada

Detailed analysis of electronic waste (e-waste) generation and composition is of utmost importance for the proper management of growing e-waste stream worldwide, containing both hazardous and valuable materials. Considering the absence of such comprehensive and up-to-date studies in Canada, this work presents the first estimate of put-on-market electrical and electronic equipment (EEE), the in-use stocks of EEE and e-waste generation in Canada from 1971 to 2030 for 51 product categories comprising 198 product types. Using a dynamic material flow analysis (MFA), the put-on-market EEE is estimated based on trade data retrieved from national and international import and export statistics, and the in-use stocks of EEE and the resulting e-waste are calculated using the Weibull distribution function. The results show that the total mass of EEE within the 60-year period is estimated to be 42.3 million tonnes, with an annual average growth rate of approximately 0.5%. By 2030, the total accumulated in-use stock of EEE is estimated to exceed 13 million tonnes. The estimated e-waste over the 60-year timespan is 29.1 million tonnes. The total annual e-waste generation in Canada is calculated to be 252 kilo tonnes (kt) and 954 kt in the years 2000 and 2020 respectively, which is estimated to reach 1.2 million tonnes by 2030. The e-waste generation per capita increased from 8.3 kg in 2000 to 25.3 kg in 2020 and is estimated to reach 31.5 kg by 2030. This quantification provides valuable insights to policymakers for setting up targets for waste reduction and identifying the resource circularity potential for efficient management of e-waste.

A review of methods to trace material flows into final products in dynamic material flow analysis: From industry shipments in physical units to monetary input–output tables, Part 1

AbstractDynamic material flow analysis (dMFA) is widely used to model stock‐flow dynamics. To appropriately represent material lifetimes, recycling potentials, and service provision, dMFA requires data about the allocation of economy‐wide material consumption to different end‐use products or sectors, that is, the different product stocks, in which material consumption accumulates. Previous estimates of this allocation only cover few years, countries, and product groups. Recently, several new methods for estimating end‐use product allocation in dMFA were proposed, which so far lack systematic comparison. We review and systematize five methods for tracing material consumption into end‐use products in inflow‐driven dMFA and discuss their strengths and limitations. Widely used data on industry shipments in physical units have low spatio‐temporal coverage, which limits their applicability across countries and years. Monetary input–output tables (MIOTs) are widely available and their economy‐wide coverage makes them a valuable source to approximate material end‐uses. We find four distinct MIOT‐based methods: consumption‐based, waste input–output MFA (WIO‐MFA), Ghosh absorbing Markov chain, and partial Ghosh. We show that when applied to a given MIOT, the methods’ underlying input–output models yield the same results, with the exception of the partial Ghosh method, which involves simplifications. For practical applications, the MIOT system boundary must be aligned to those of dMFA, which involves the removal of service flows, sector (dis)aggregation, and re‐defining specific intermediate outputs as final demand. Theoretically, WIO‐MFA, applied to a modified MIOT, produces the most accurate results as it excludes massless and waste transactions. In part 2 of this work, we compare methods empirically and suggest improvements for aligning MIOT‐dMFA system boundaries.

Dynamic material flow analysis of lutetium resources in China during 2011-2020

Dynamic material flow analysis of lutetium resources in China during 2011-2020