Dynamic Substance Flow Analysis Research Articles

Securing Indium Utilization for High-Tech and Renewable Energy Industries.

Indium has emerged as a strategic metal for high-tech and renewable industries, being catalogued as a critical material to foster a greener future. Nevertheless, its global sustainability is not well addressed. Here, using dynamic substance flow analysis, we study the indium industry evolution between 2010 and 2020 and estimate its future demand in the medium and long term toward 2050 to identify potential paths and mechanisms to decrease indium losses and to identify the key stages in its life cycle. As electronics and photovoltaic industries will play a crucial role in the indium demand, we assess their indium demand employing three cumulative photovoltaic capacity scenarios (8.5, 14, and 60 TW by 2050) with different dominant photovoltaic sub-technologies. Results show that liquid-crystal displays and photovoltaic panels will drive indium future demand, increasing its current demand by 2.2-4.2, 2.6-7.0, and 6.8-38.3 times for the 8.5, 14, and 60 TW scenarios, respectively, threatening with shortages that could occur as early as the next decade. Therefore, measures to reduce losses in primary production, innovations and improvements in electronics and solar panels, and indium recycling with an effective circular economy strategy could promote and secure the future sustainability of indium.

Modeling the impact of nickel recycling from batteries on nickel demand during vehicle electrification in China from 2010 to 2050

China is promoting the production and use of electric vehicles (EVs) to achieve carbon neutrality. However, the shift will drive higher demand and tighter supply of nickel in China. We develop a stock–driven bottom–up dynamic substance flow analysis (SFA) model to simulate the demand trends of various EVs under 3 scenarios, the flow of nickel under 9 scenarios and the amount of recoverable nickel under 27 scenarios in China's EV industry from 2010 to 2050. The results indicate that China's current production capacity and primary reserves of nickel cannot meet the growing nickel demand, especially under the High EVs–LNCT scenarios, and closed–loop nickel recovery from EV batteries can effectively alleviate the demand–supply contradiction. In different scenarios, the annual recycling nickel could cover between 67.7 % and 96.6 % of the demand for EV batteries in 2050, and between 37.9 % and 58.1 % in terms of the cumulative quantity by 2050. When the low nickel battery technology is adopted and the recovery efficiency is rapidly improved, the recovered nickel would meet the demand for EV batteries to the highest degree. Therefore, sufficient attention should be paid to low–nickel battery technology and efficient recycling of spent EV batteries, which is of great significance to ensure the development of EV industry and the availability of nickel in China.

Global Historical Production, Use, In-Use Stocks, and Emissions of Short-, Medium-, and Long-Chain Chlorinated Paraffins.

The last few decades have seen ubiquitous and increasing contamination of chlorinated paraffins (CPs) worldwide. Here, we develop the first global inventories of production, use, in-use stocks, and emissions of total CPs, including the short-, medium- and long-chain components (SCCPs, MCCPs, and LCCPs) during 1930-2020 using a dynamic substance flow analysis model named Chemical in Products Comprehensive Anthroposhpheric Fate Estimation. The model estimates that a total of ∼33 million metric tons of CPs have been produced and used globally, ∼40% of which still resided in in-use products by 2020 and is available for long-term emissions in the next decades. Global cumulative emissions of CPs have increased to ∼5.2 million metric tons by 2020, with SCCPs, MCCPs, and LCCPs accounting for ∼30, 40, and 30%, respectively. While the production, use, and emissions of CPs started declining in regions such as Western Europe, they remain high in China. The model also suggests that homologues with 10, 14, and 22-23 carbons were predominant in the cumulatively produced and emitted SCCPs, MCCPs, and LCCPs, respectively. The emission estimates were evaluated by generating environmental concentrations that are comparable to literature-reported environmental monitoring data. Our estimates provide opportunities to link the environmental fate and occurrence of CPs to emission sources and lay the basis for future risk-reduction strategies of CPs around the world.

Toward sustainable utilization of tungsten: Evidence from dynamic substance flow analysis from 2001 to 2019 in China

Tungsten is one strategic metal with diverse applications ranging from military, infrastructure to chemical industry. China is the biggest tungsten supplier and consumer in the world, but few studies focus on the domestic tungsten supply and demand. By conducting a hybrid dynamic substance flow analysis, this study investigates China's tungsten flow patterns from 2001 to 2019. Various flows (transformation, loss, trade and recycling flows) and stocks are explored, covering all the relevant aspects of tungsten extraction, production, consumption, trade and waste management. Results present that China had extracted around 1344 metric kilo-tons (kt) tungsten ores from earth crust, consumed 634 kt domestically and exported 381 kt to other countries during the study period. Key findings include: 1) unstable production capacity had led to 136.16 kt of tungsten surplus during the study period; 2) 309 kt of tungsten were lost in tailings due to inefficient mining and beneficiation technologies; 3) domestic industry upgrade and rapid economic development induced dynamic changes of tungsten trade structure in China; 4) only 17.72% of end-of-life (EoL) products had been recycled during the study period. Finally, policy recommendations are raised to improve the overall tungsten resource efficiency from governance, economic instruments and technology perspectives.

Dynamic substance flow analysis of lead in the fossil fuel system of China from 1980 to 2018

Lead is mostly found with zinc ores, but is also abundant in fossil fuels. However, the anthropogenic cycle of lead in fossil fuel system has rarely been reported. This study expounds on the evolution of lead metabolism in China's fossil fuel system from 1980 to 2018 through dynamic substance flow analysis. The quantities and structures of lead flows and stocks in the system changed significantly. After the prohibition of leaded gasoline, raw coal became the main source of lead in the system, reaching 101 kt Pb/yr in 2018. The lead outflow of the system underwent a transformation from gas phase to solid phase. The atmospheric lead emission dropped from the highest 20 kt/yr to 4 kt/yr. Most of the lead in the system accumulated in coal-based solid waste. In the past 40 years, 677 kt of lead accumulated in constructions due to the utilization of coal-based solid waste, and 657 kt of lead was left in the redundant coal-based solid waste. The main lead emission stage gradually shifted from the use stage to the waste management stage. Although the flow of lead in fossil fuels is small, there is no significant difference between unintentional (consider only fossil fuels) and intentional use of lead emissions to the atmosphere and landfills. China should improve the utilization of coal-based solid waste, and strengthen the management of landfills and dumps and the surrounding environmental monitoring.

Methodological Study of Evaluating Future Lightweight Vehicle Scenarios and CO2 Reduction Based on Life Cycle Assessment

Changing the material composition of vehicles from steel to alternative materials, such as aluminum and magnesium, is being explored to reduce the weight of vehicles. Further, this change could lead to a significant reduction in vehicular CO2 emissions. To analyze this relationship and estimate the CO2 reduction effect over the life cycle, it is important to create potential scenarios by considering the logistics balance from material production to recycling. Therefore, this study aims to quantitatively predict the amount of renewable energy employed in vehicles, along with the various alternative materials used; further, the demand for aluminum and magnesium is predicted. These predictions are made via several multivariate analyses and a dynamic substance flow analysis (SFA) to explore future scenarios. It is estimated that 65% of rolled aluminum can be obtained from a secondary alloy via closed-loop recycling of rolled products in a sustainable development scenario. However, 510 kt/year of end of life scrap aluminum must be imported from overseas to provide 90% of the secondary alloy required in cast and die cast parts. The overall CO2 reduction amount is predicted to be 3920 kt/year in the 2040 sustainable development scenario. This study successfully demonstrated that combining SFA and life cycle assessment is efficient for quantitatively estimating the synergies of renewable energy implementation, vehicular weight reduction, and recycling.

Dynamic Substance Flow Analysis of Rhenium Related to the Demand for Civil Aircrafts

Dynamic Substance Flow Analysis of Rhenium Related to the Demand for Civil Aircrafts

Global Historical Stocks and Emissions of PBDEs.

The first spatially and temporally resolved inventory of BDE28, 47, 99, 153, 183, and 209 in the anthroposphere and environment is presented here. The stock and emissions of PBDE congeners were estimated using a dynamic substance flow analysis model, CiP-CAFE. To evaluate our results, the emission estimates were used as input to the BETR-Global model. Estimated concentrations were compared with observed concentrations in air from background areas. The global (a) in-use and (b) waste stocks of ∑5BDE(28, 47, 99, 153, 183) and BDE209 are estimated to be (a) ∼25 and 400 kt and (b) 13 and 100 kt, respectively, in 2018. A total of 6 (0.3-13) and 10.5 (9-12) kt of ∑5BDE and BDE209, respectively, has been emitted to the atmosphere by 2018. More than 70% of PBDE emissions during production and use occurred in the industrialized regions, while more than 70% of the emissions during waste disposal occurred in the less industrialized regions. A total of 70 kt of ∑5BDE and BDE209 was recycled within products since 1970. As recycling rates are expected to increase under the circular economy, an additional 45 kt of PBDEs (mainly BDE209) may reappear in new products.

Stocks, flows and emissions of DBDPE in China and its international distribution through products and waste

Decabromodiphenyl ethane (DBDPE) is an alternative to the commercial decabromodiphenyl ether (deca-BDE) mixture but has potentially similar persistence, bioaccumulation potential and toxicity. While it is widely used as a flame retardant in electrical and electronic equipment (EEE) in China, DBDPE could be distributed globally on a large scale with the international trade of EEE emanating from China. Here, we performed a dynamic substance flow analysis to estimate the time-dependent mass flows, stocks and emissions of DBDPE in China, and the global spread of DBDPE originating in China through the international trade of EEE and e-waste. Our analysis indicates that, between 2006 and 2016, ∼230 thousand tonnes (kt) of DBDPE were produced in China; production, use and disposal activities led to the release of 196 tonnes of DBDPE to the environment. By the end of 2016, ∼152 kt of the DBDPE produced resided in in-use products across China. During the period 2000–2016, ∼39 kt of DBDPE were exported from China in EEE products, most of which (>50%) ended up in North America. Based on projected trends of China's DBDPE production, use and EEE exports, we predict that, by 2026, ∼74 and ∼14 kt of DBDPE originating in China will reside in in-use and waste stocks, respectively, in regions other than mainland China, which will act as long-term emission sources of DBDPE worldwide. This study discusses the considerable impact of DBDPE originating in China and distributed globally through the international trade of EEE; this is projected to occur on a large scale in the near future, which necessitates countermeasures.

Elucidating the Variability in the Hexabromocyclododecane Diastereomer Profile in the Global Environment.

Hexabromocyclododecane (HBCDD) is a hazardous flame retardant subject to international regulation. Whereas γ-HBCDD is a dominant component in the technical HBCDD mixture, the diastereomer profile in environmental samples shows substantial temporal and spatial variations, ranging from γ- to α-HBCDD-dominant. To explain such variability, we simulate the global emissions and fate of HBCDD diastereomers, using a dynamic substance flow analysis model (CiP-CAFE) coupled to a multimedia environmental fate model (BETR-Global). Our modeling results indicate that, as of 2015, 340-1000 tonnes of HBCDD have been emitted globally, with slightly more γ-HBCDD (50%-65%) than α-HBCDD (30%-50%). Emissions of γ-HBCDD primarily originate from production and other industrial processes, whereas those of α-HBCDD are mainly associated with the use and end-of-life disposal of HBCDD-containing products. Presently, α-HBCDD dominates the contamination in the air of populated areas, while γ-HBCDD is more abundant in remote background areas and in regions with HCBDD production and processing facilities. Globally, the relative abundance of α-HBCDD is anticipated to increase after production of HBCDD is banned. Due to isomerization, α-HBCDD accumulates to a larger extent than γ-HBCDD in Arctic surface media. Since α-HBCDD is more persistent and bioaccumulative than other diastereomers, isomerization has bearing on the potential environmental and health impacts on a global scale.

The Chinese copper cycle: Tracing copper through the economy with dynamic substance flow and input-output analysis

Abstract China has become a major user of copper as well as a producer of copper containing products. We present a dynamic model of Chinese copper stocks and flows in the period from 1990 to 2015. The model results indicate that China's per-capita in-use copper stock has grown from about 7 kg in 1990 to close to 60 kg in 2015. At the same time, total copper imports have increased from approximately 0.65 Mt per year to close to 10 Mt. One of the peculiarities of the Chinese copper cycle is that a comparatively large fraction ( ≈ 1,4 Mt) of these imports are made up of scrap, which China re-processes into new products. At the same time, China has relatively low domestic recycling efficiencies. The substance flow perspective is extended with national accounting data, which allows for a portrayal of the interconnection between copper flows and the wider economic structure. It is thus possible to identify the economic sectors which not only directly but also indirectly require copper for the provision of their goods and services.

Revisiting the Contributions of Far- and Near-Field Routes to Aggregate Human Exposure to Polychlorinated Biphenyls (PCBs).

The general population is exposed to polychlorinated biphenyls (PCBs) by consuming food from far-field contaminated agricultural and aquatic environments, and inhalation and nondietary ingestion in near-field indoor or residential environments. Here, we seek to evaluate the relative importance of far- and near-field routes by simulating the time-variant aggregate exposure of Swedish females to PCB congeners from 1930 to 2030. We rely on a mechanistic model, which integrates a food-chain bioaccumulation module and a human toxicokinetic module with dynamic substance flow analysis and nested indoor-urban-rural environmental fate modeling. Confidence in the model is established by successfully reproducing the observed PCB concentrations in Swedish human milk between 1972 and 2016. In general, far-field routes contribute most to total PCB uptake. However, near-field exposure is notable for (i) children and teenagers, who have frequent hand-to-mouth contact, (ii) cohorts born in earlier years, e.g., in 1956, when indoor environments were severely contaminated, and (iii) lighter chlorinated congeners. The relative importance of far- and near-field exposure in a cross-section of individuals of different age sampled at the same time is shown to depend on the time of sampling. The transition from the dominance of near- to far-field exposure that has happened for PCBs may also occur for other chemicals used indoors.

Model-based screening for critical wet-weather discharges related to micropollutants from urban areas

Wet-weather discharges contribute to anthropogenic micropollutant loads entering the aquatic environment. Thousands of wet-weather discharges exist in Swiss sewer systems, and we do not have the capacity to monitor them all. We consequently propose a model-based approach designed to identify critical discharge points in order to support effective monitoring.We applied a dynamic substance flow model to four substances representing different entry routes: indoor (Triclosan, Mecoprop, Copper) as well as rainfall-mobilized (Glyphosate, Mecoprop, Copper) inputs. The accumulation on different urban land-use surfaces in dry weather and subsequent substance-specific wash-off is taken into account. For evaluation, we use a conservative screening approach to detect critical discharge points. This approach considers only local dilution generated onsite from natural, unpolluted areas, i.e. excluding upstream dilution.Despite our conservative assumptions, we find that the environmental quality standards for Glyphosate and Mecoprop are not exceeded during any 10-min time interval over a representative one-year simulation period for all 2500 Swiss municipalities. In contrast, the environmental quality standard is exceeded during at least 20% of the discharge time at 83% of all modelled discharge points for Copper and at 71% for Triclosan. For Copper, this corresponds to a total median duration of approximately 19 days per year. For Triclosan, discharged only via combined sewer overflows, this means a median duration of approximately 10 days per year. In general, stormwater outlets contribute more to the calculated effect than combined sewer overflows for rainfall-mobilized substances. We further evaluate the Urban Index (Aurban,impervious/Anatural) as a proxy for critical discharge points: catchments where Triclosan and Copper exceed the corresponding environmental quality standard often have an Urban Index >0.03.A dynamic substance flow analysis allows us to identify the most critical discharge points to be prioritized for more detailed analyses and monitoring. This forms a basis for the efficient mitigation of pollution.

Dynamic Substance Flow Analysis of Neodymium and Dysprosium Associated with Neodymium Magnets in Japan

SummaryRecycling of neodymium and dysprosium is of great interest because of the rapid growth in their demand and limited supply of new resources. To promote recovery from end‐of‐life (EoL) products, it is desirable to quantify the recycling potentials of neodymium and dysprosium by their end use. This study characterized the substance flows of neodymium and dysprosium associated with neodymium magnets in Japan by conducting a dynamic substance flow analysis. A bottom‐up approach was employed in the analysis to estimate annual consumption by end use. Factors used in the analysis were the amounts of rare earth contents, weight of a magnet used for each product, adoption ratios of neodymium magnet usage in each product, and lifetime of products. It was found that the amount of neodymium entering use was approximately half of the domestic consumption; the balance existing in final products that were exported from Japan. The economic feasibility of recycling neodymium magnets was evaluated for their largest two end uses: driving motors in hybrid electric vehicles (HEVs) and compressors in air conditioners. It was found that recycling the neodymium magnets used in the driving motors has the potential for economic feasibility in Japan. The result showed that lower transportation costs for recovered magnets can make the recycling economically feasible regardless of the content rate and the price of metals. The future increase of EoL HEVs contributes to the feasibility of recycling with a profit in the upcoming years. Strategies for more profitable recycling are concentrating scrap motors or magnets among recycling factories or selecting specific factories that deal with EoL HEVs.

Tracking chemicals in products around the world: introduction of a dynamic substance flow analysis model and application to PCBs

Dynamically tracking flows and stocks of problematic chemicals in products (CiPs) in the global anthroposphere is essential to understanding their environmental fates and risks. The complex behavior of CiPs during production, use and waste disposal makes this a challenging task. Here we introduce and describe a dynamic substance flow model, named Chemicals in Products - Comprehensive Anthropospheric Fate Estimation (CiP-CAFE), which facilitates the quantification of time-variant flows and stocks of CiPs within and between seven interconnected world regions and the generation of global scale emission estimates. We applied CiP-CAFE to polychlorinated biphenyls (PCBs), first to evaluate its ability to reproduce previously reported global-scale atmospheric emission inventories and second to illustrate its potential applications and merits. CiP-CAFE quantifies the pathways of PCBs during production, use and waste disposal stages, thereby deducing the temporal evolution of in-use and waste stocks and identifying their long-term final sinks. Time-variant estimates of PCB emissions into air, water and soil can be attributed to different processes and be fed directly into a global fate and transport model. By capturing the international movement of PCBs as technical chemicals, and in products and waste, CiP-CAFE reveals that the extent of global dispersal caused by humans is larger than that occurring in the natural environment. Sensitivity analysis indicates that the model output is most sensitive to the PCB production volume and the lifetime of PCB-containing products, suggesting that a shortening of that lifetime is key to reducing future PCB emissions.

Long-term emissions of hexabromocyclododecane as a chemical of concern in products in China

There has been ever-increasing international interest in investigating the long-term emissions of chemicals in products (CiPs) throughout their entire life cycle in the anthroposphere. Hexabromocyclododecane (HBCDD) is a contemporary example of special interest due to the recent listing of this hazardous flame retardant in the Stockholm Convention and the consequent need for parties to take appropriate measures to eliminate this compound. Here, we conducted a scenario-based dynamic substance flow analysis, coupled with interval linear programming, to forecast the future HBCDD emissions in China in order to assist with the implementation of the Stockholm Convention in this current world's predominant HBCDD manufacturing and consuming country. Our results indicate that, under a business-as-usual scenario, the cumulative HBCDD production will amount to 238,000tonnes before its phase-out, 79% of which will be consumed in domestic market, accumulate as stocks in flame-retarded polystyrene insulation boards, and ultimately end up in demolition waste. While the production is scheduled to end in ca. 2021, emissions of HBCDD would continue until after 2100. For the entire simulation period 2000–2100, 44% of total cumulative emissions will arise from the industrial manufacture of HBCDD-associated end-products, whereas 49% will come from the end-of-life disposals of HBCDD-containing waste. The most effective end-of-life disposal option for minimizing emissions we found was, a pre-demolition screening combined with complete incineration. Our study warns of the huge challenges that China would face in its eliminating HBCDD contamination in the following decades, and provides an effective methodology for a wider range of countries to recognize and tackle their long-term emission problems of hazardous CiPs.

The future of copper in China—A perspective based on analysis of copper flows and stocks

This study attempts to speculate on the future of copper metabolism in China based on dynamic substance flow analysis. Based on tremendous growth of copper consumption over the past 63years, China will depict a substantially increasing trend of copper in-use stocks for the next 30years. The highest peak will be possibly achieved in 2050, with the maximum ranging between 163Mt and 171Mt. After that, total stocks are expected to slowly decline 147–154Mt by the year 2080. Owing to the increasing demand of in-use stocks, China will continue to have a profound impact on global copper consumption with its high import dependence until around 2020, and the peak demand for imported copper are expected to approach 5.5Mt/year. Thereafter, old scrap generated by domestic society will occupy an increasingly important role in copper supply. In around 2060, approximately 80% of copper resources could come from domestic recycling of old scrap, implying a major shift from primary production to secondary production. With regard to the effect of lifetime distribution uncertainties in different end-use sectors of copper stocks on the predict results, uncertainty evaluation was performed and found the model was relatively robust to these changes.

Worth of metal gleaning in mining and recycling for mineral conservation

Mitigating mineral extraction is considered to be an important challenge in prolonging resource supplies and protecting the environment at mining sites. This challenge can be faced by retaining metal resources within the anthroposphere with adequate technologies and policies for reducing losses to the environment. In mining and mineral processing, considerable amounts of metals are lost as tailings. In recycling, metal recovery from end-of-life products is limited by economic and technological restrictions. In this study, we evaluate the potential for mitigating mineral extraction by reducing the loss rates in mining and recycling. In this study, global substance flow analysis is conducted for seven metals and the importance of recycling is determined for each metal. Furthermore, the change in potential recycling in the future is discussed in combination with dynamic substance flow analysis. We found that reducing the loss rate in recycling could not fully realize mineral conservation in the year 2000, except in the case of lead. However, we also showed that it will become important as the metal discard increases in the future. The framework of this study supports the sustainable use of metals by introducing the right technologies and policies at the right time.

Static and dynamic flow analysis of PBDEs in plastics from used and end-of-life TVs and computer monitors by life cycle in Korea

This study focused on a quantitative substance flow analysis (SFA) of polybrominated diphenyl ethers (PBDEs) in plastics from obsolete TVs and computer monitors that often contain large amounts of the flame retardants. According to the results of the static SFA study, 1.87tons and 0.28tons of PBDEs from newly manufactured TVs and computer monitors were introduced into households in 2011 in Korea, respectively. There were approximately 924tons and 90.3tons of PBDEs present in TVs and computer monitors in households during product use, respectively. The results of the dynamic SFA study indicated that in 2017 the amount of PBDEs from TVs and computer monitors in the recycling stage is expected to be 2.63tons and 0.1tons, respectively. Large fractions of PBDEs from used TVs are present in recycled plastics, while PBDE-containing computer monitors are exported to Southeast Asian countries. This research indicates that PBDEs were emitted the most from recycled plastic pellet processes upon recycling. Further study may be warranted to focus the flow of PBDEs in recycled plastic products in order to determine the final destination and disposal of these chemicals in the environment.

Long-Term Strategies for Increased Recycling of Automotive Aluminum and Its Alloying Elements

Aluminum recycling currently occurs in a cascading fashion, where some alloys, used in a limited number of applications, absorb most of the end-of-life scrap. An expected increase in scrap supply in coming decades necessitates restructuring of the aluminum cycle to open up new recycling paths for alloys and avoid a potential scrap surplus. This paper explores various interventions in end-of-life management and recycling of automotive aluminum, using a dynamic substance flow analysis model of aluminum and its alloying elements with resolution on component and alloy level (vehicle-component-alloy-element model). It was found that increased component dismantling before vehicle shredding can be an effective, so far underestimated, intervention in the medium term, especially if combined with development of safety-relevant components such as wheels from secondary material. In the long term, automatic alloy sorting technologies are most likely required, but could at the same time reduce the need for magnesium removal in refining. Cooperation between the primary and secondary aluminum industries, the automotive industry, and end-of-life vehicle dismantlers is therefore essential to ensure continued recycling of automotive aluminum and its alloying elements.