Dynamic Material Flow Model Research Articles

Dynamic material flow analysis of construction materials in Saudi Arabia: Strategies for sustainability of residential buildings

Globally, the expansion of building infrastructure has serious environmental implications due to emissions from cement and steel. The construction industry uses the vast majority of cement and steel produced globally and locally. Consequently, this paper proposes a model to estimate and mitigate future material flow emissions into residential buildings in Saudi Arabia. First, a dynamic material flow model is used to quantify material flows and stock in residential buildings. The evolution of Saudi housing stock and related steel and cement are simulated from 1950 to 2100. Second, various strategies such as material efficiency improvement, lifetime extension, and reducing production emissions are simulated to reduce emissions caused by cement and steel. The findings indicate that implementing substantial material efficiency improvements can result in 33 %–46 % reductions of cumulative steel and cement emissions from 2023 to 2100, respectively. Furthermore, improving material efficiency measures could result in over 80 % reductions in emissions for steel over the same period. Reducing the ratio of clinker to supplementary cementitious materials in cement to 75 % could reduce cumulative cement emissions by 129 million tCO2e (17 %). Adoption of high material efficiency practices in cement use, low clinker cement, and waste as fuel can reduce emissions by 70 %. The findings of this study contribute to a better understanding of future emissions from building materials used in residential buildings, as well as the impact of emission mitigation strategies on future emissions, which will help decision-makers and researchers develop policies and research.

Inertia of Technology Stocks: A Technology-Explicit Model for the Transition toward a Low-Carbon Global Aluminum Cycle.

Low-carbon technologies are essential for the aluminum industry to meet its climate targets despite increasing demand. However, the penetration of these technologies is often delayed due to the long lifetimes of the industrial assets currently in use. Existing models and scenarios for the aluminum sector omit this inertia and therefore potentially overestimate the realistic mitigation potential. Here, we introduce a technology-explicit dynamic material flow model for the global primary (smelters) and secondary (melting furnaces) aluminum production capacities. In business-as-usual scenarios, we project emissions from smelters and melting furnaces to rise from 710 Mt CO2-eq./a in 2020 to 920-1400 Mt CO2-eq./a in 2050. Rapid implementation of inert anodes in smelters can reduce emissions by 14% by 2050. However, a limitation of emissions compatible with a 2 °C scenario requires combined action: (1) an improvement of collection and recycling systems to absorb all the available postconsumer scrap, (2) a fast and wide deployment of low-carbon technologies, and (3) a rapid transition to low-carbon electricity sources. These measures need to be implemented even faster in scenarios with a stronger increase in aluminum demand. Lock-in effects are likely: building new capacity using conventional technologies will compromise climate mitigation efforts and would require premature retirement of industrial assets.

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.

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.

Hazardous waste from the global shipbreaking industry: Historical inventory and future pathways

Shipbreaking activities release hazardous wastes (namely, oil, asbestos, other landfillable wastes, and incinerable wastes) that harm both workers' health and the environment. However, an accurate and detailed emission inventory to support policy design of the greening reform remains lacking. By developing a framework that combines dynamic material flow model, global change assessment model and scenario analysis, this study carries out historical analysis and future projection of global ship scrap and pollutant emissions, based on ship scrap datasets. Our results show that shipbreaking sites have gradually shifted from more developed regions such as Taiwan, the European Union (EU), Japan, and Russia to the three less developed Southern Asian countries, Bangladesh, India, and Pakistan, in the past four decades. Waste emissions in these three countries have increased significantly by 6.5 times between 1990 and 2019. Although the volume of scrapped ships is expected to reach 75–95 million gross tons per year by 2050, the cumulative waste emissions from 2020 to 2050 will be reduced by 92% and 79% under the EU Convention and the Hong Kong Convention scenario, respectively. Lastly, policy implications such as how to mitigate the adverse impact of shipbreaking activities after the international conventions enter into force are comprehensively discussed.

How will tramp elements affect future steel recycling in Europe? – A dynamic material flow model for steel in the EU-28 for the period 1910 to 2050

Global steel production has undergone massive growth since WWII. In recent decades, however, affluent regions such as the US and the EU-28 have been experiencing a saturation of the steel market. Stagnant steel production volumes and increased post-consumer scrap volumes are the consequence. The increasing shares of post-consumer scrap provide the opportunity to increase the scrap rate (share of utilized scrap) in crude steel production. However, steel recycling has a major limiting factor: the content of specific tramp elements.In the present study, a dynamic material flow model for steel is used to compare available scrap with crude steel demand on a quantitative and qualitative level (tramp element content of Cu, Ni, Mo, Cr and Sn). The results show that post-consumer scrap increases from 80 Mt/yr (65% of all scrap available) in 2020 to more than 100 Mt/yr (75% of all scrap available) in 2050. Based on the model, the development of the yearly surplus of low purity scrap (for which there is a higher supply than demand) was assessed via material pinch analysis. The low purity scrap surplus rises further, from today's 20 Mt/yr (2020) to 43 Mt/yr in 2050. Assuming that the current handling of scrap continues, the maximal scrap rate is shown to lie at around 55%, while the potential scrap rate (without quality constraints) could reach 75%. The dilution of low purity scrap with high purity resources would allow the utilization of all scrap until 2040 if the current collection scheme remains in place.

The impact of climate policy implementation on lithium, cobalt and nickel demand: The case of the Dutch automotive sector up to 2040

The Dutch national climate agreement (‘Klimaatakkoord’), stipulates a 49% decrease in greenhouse gas (GHG) emissions by 2030, relative to the 1990 level. To accommodate this target, the passenger vehicles sector must reduce its GHG emissions by 30% in 2030, which likely will come about by replacing internal combustion engine vehicles with electric vehicles. In this study, a dynamic material flow model combined was applied to investigate the future demand for (and metabolism of) lithium, cobalt, and nickel within various scenarios of Dutch electric vehicle markets stemming from climate policy implementation. Our results show that by 2040 the demand for electric vehicles rapidly grows by an order of magnitude, which expands by two orders of magnitude the annual accumulation of these metals in the Netherlands when compared to the 2019 levels. Lithium and nickel demand will keep increasing through 2040, while the demand trend of cobalt will start to drop after 2030, due to changes in battery technology. Increasing the EV driving range and replacing EV batteries during an EV lifetime will increase the demand for these metals by 10%–19%. Conversely, extending the average battery lifetime to meet the vehicle lifetime could reduce the demand of these metals by 30%. Due to the low open-loop recycling of these metals, policies must seek to minimize their presence in the electric mobility sector, while also stimulating better recycling practices and infrastructure. • The demand for electric vehicles (EV) and Li, Co and Ni used in the EV batteries will be accelerated under the promotion of the Dutch climate policy. • The innovation in battery cathode technology is one of the factors to diversify the requirements of raw materials. • The extension of battery service life is important to lessen the demand for primary materials.

Representation, Propagation, and Interpretation of Uncertain Knowledge in Dynamic Probabilistic Material Flow Models

The determination of the environmental concentration of a pollutant is a crucial step in the risk assessment of anthropogenic substances. Dynamic probabilistic material flow analysis (DPMFA) is a method to predict flows of substances to the environment that can be converted into environmental concentrations. In cases where direct quantitative measurements of concentrations are impossible, environmental stocks are predicted by reproducing the flow processes creating these stocks in a mathematical model. Incomplete parameter knowledge is represented in the form of stochastic distributions and propagated through the model using Monte Carlo simulation. This work discusses suitable means for the model design and the representation of system knowledge from several information sources of varying credibility as model parameter distributions, further evaluation of the simulation outcomes using sensitivity analyses, and the impacts of parameter uncertainty on the total uncertainty of the simulation output. Based on a model developed in a case study of carbon nanotubes in Switzerland, the modeling process, the representation and interpretation of the simulation results are described and approaches to sensitivity and uncertainty analyses are demonstrated. Finally, the overall approach is summarized and provided in the form of a set of modelling and evaluation rules for DPMFA studies.

Global wind power development leads to high demand for neodymium praseodymium (NdPr): A scenario analysis based on market and technology development from 2019 to 2040

In recent years, to cope with climate change, the global energy structure has been subject to constant transformation. Wind power has become one of the main forms of renewable energy, and as basic equipment in wind power generation, wind turbines have become more technologically advanced over the years. Neodymium praseodymium (NdPr) has become the key material for the most recent permanent magnet wind turbines. Therefore, the development of the global wind power market has a great impact on the demand for NdPr. This paper sets three scale scenarios of the future wind power market—a baseline scenario, a development scenario and a rapid development scenario—and estimates recycling potential from end-of-life (EOL) wind turbines using a dynamic material flow model. The results show that under different scales, the demand for NdPr ranges from 2.28E+05 to 7.88E+05 t during 2019–2040. In the long term, the rapid rise in offshore wind power projects will promote recycling technology as a promising strategy for diversifying the NdPr supply.

Dynamic material flow and stock analysis of residential buildings by integrating rural–urban land transition: A case of Shanghai

In rapidly developing countries, such as China, considerable quantities of construction materials have been mobilized with the fast expansion of urban areas. The rural to urban land use transition, especially the upgrade and redevelopment of original rural areas, is a noted driver of material flows. This rural–urban land transition should be incorporated into material flow and stock analyses to provide a more accurate analysis. In this study, a dynamic material flow and stock model that integrates the historical rural–urban land transition was developed to explore the quantity of material stocks and demolition waste from residential buildings in Shanghai—the largest megacity in China from 1950 to 2100. Our results show that the material stocks from residential buildings in Shanghai increased 41-fold from 1950 to 2010, about 957 MMT (million metric tons), and is estimated to be saturated around 2040. Material stocks have experienced asynchronized growth in rural areas, central urban areas, and rural–urban land transition zones (RULT zones) in Shanghai. Until 2040, the RULT zones in Shanghai will be the largest material repository (62%), followed by central urban areas (20%), and rural areas (18%). The amount of demolition waste, which accounted for 10 MMT in 2010, is expected to peak at 29 MMT in 2060s. This suggests the need for a deliberate investment plan to increase waste treatment capacity. In addition, the dominant component of demolition waste will shift from brick to concrete after 2020s. The RULT zones will contribute two-thirds of demolition waste to Shanghai until the 2060s. If we do not consider the reality of the physical status of buildings in RULT zones, the demolition waste will be underestimated by the maximum of 57% in 2003 in urban areas. The key findings on the trend of construction and demolition (C&D) waste generation and the significant contribution of RULT zones can be used as a reference for the strategic planning of treatment facilities. This research framework can be also used to estimate the amount of C&D waste in other fast-developing cities in China and other countries.

Potential Contribution of Secondary Materials to Overall Supply - The Example of the European Cobalt Cycle

Higher efficiency in raw material recycling is discussed as a key strategy to decrease the environmental impact of resource consumption and to improve materials’ availability in order to mitigate supply risks. However, particularly in the case of technology metals, demand is driven by specific emerging technologies from which recycling will not be possible before the end of their useful lifetimes. Hence, the availability of secondary materials is limited by the amount of obsolete products as well as their collection, separation and treatment during waste management and recycling. In this paper, we present the results of a dynamic material flow model for cobalt as a key raw material for lithium-ion batteries at an European level (EU28). This model aims at quantifying the current state of recycling and future recycling potentials from end-of-life (EoL) product flows. While it is expectable that obsolete large battery packs from (hybrid) electric vehicles will be efficiently collected in future, EoL Li-ion battery flows will remain dominated by smaller electronic equipment (smartphones, laptops etc.) in the coming years and the model results show a significant potential for improvements in collection and material recovery from EoL batteries in Europe. A major challenge will be the collection of smaller batteries and Waste Electrical and Electronic Equipment (WEEE) in general from which a significant share of total European cobalt demand could be recovered in the coming years.

Recovering the “new twin”: Analysis of secondary neodymium sources and recycling potentials in Europe

Sustainable management strategies for securing long–term supply of rare earth elements is priority for Europe due to a complex and interlinked production chain and its dependence on Chinese export. Among rare earth elements, neodymium captured most attention due to its essential role in a wide spectrum of applications including green–energy technologies such as wind turbines and electric vehicles. Being complementary to primary production, end–of–life recycling would diversify neodymium supply, relieve the Chinese dominance on primary production and contrast the balance problem. However, neodymium recycling at end–of–life is not yet in place.In this work, we developed a dynamic material flow model to investigate neodymium stocks and flows in the EU–28 to 2016. The analysis enabled a detailed investigation of secondary sources of neodymium, which set essential boundary conditions for material recovery and recycling. We found that roughly up to 50% of the annual neodymium demand in the EU–28 could be met by domestic secondary supply, if latent recycling potentials were turned into actual capacity. Significant energy savings and GHG emissions cut could be also attained. However, product design, end–of–life collection, and scrap price issues are primary obstacles to neodymium recovery. Thus, unless going beyong those limits, establishing and maintaining a sustainable recycling chain for neodymium in the EU–28 will remain problematic.

Shedding Light on the Anthropogenic Europium Cycle in the EU–28. Marking Product Turnover and Energy Progress in the Lighting Sector

Phase-out strategies for incandescent bulbs in favor of advanced energy-efficiency lighting systems such as fluorescent lamps and solid-state technology have considerably reduced the energy use for lighting, but have also resulted in dependence on many critical materials like rare earth elements and shifted the attention to sustainable use and recovery of resources. In this work, a dynamic material flow model was developed to analyze the socio-economic metabolism of europium in the EU–28. The analysis shows that europium marked product turnover and progress in lighting efficiency, with this element being employed both in traditional and novel lighting technology to provide luminescence. The results also demonstrate that the current anthropogenic reserve could constitute an attractive source of secondary europium with substantial potentials for environmental benefits. However, nonexistent recycling and market forces hinder strategies for material circularity. In particular, the transition from fluorescent lamps to solid-state technology is quickly decreasing the demand for europium. This trend adds further constraints to the creation of a sustainable recycling industry for europium, with primary sources that might remain the preferable route to supply phosphors to future lighting systems.

Environmental risk assessment of engineered nano-SiO2 , nano iron oxides, nano-CeO2 , nano-Al2 O3 , and quantum dots.

Many research studies have endeavored to investigate the ecotoxicological hazards of engineered nanomaterials (ENMs). However, little is known regarding the actual environmental risks of ENMs, combining both hazard and exposure data. The aim of the present study was to quantify the environmental risks for nano-Al2 O3 , nano-SiO2 , nano iron oxides, nano-CeO2 , and quantum dots by comparing the predicted environmental concentrations (PECs) with the predicted-no-effect concentrations (PNECs). The PEC values of these 5 ENMs in freshwaters in 2020 for northern Europe and southeastern Europe were taken from a published dynamic probabilistic material flow analysis model. The PNEC values were calculated using probabilistic species sensitivity distribution (SSD). The order of the PNEC values was quantum dots < nano-CeO2 < nano iron oxides < nano-Al2 O3 < nano-SiO2 . The risks posed by these 5 ENMs were demonstrated to be in the reverse order: nano-Al2 O3 > nano-SiO2 > nano iron oxides > nano-CeO2 > quantum dots. However, all risk characterization values are 4 to 8 orders of magnitude lower than 1, and no risk was therefore predicted for any of the investigated ENMs at the estimated release level in 2020. Compared to static models, the dynamic material flow model allowed us to use PEC values based on a more complex parameterization, considering a dynamic input over time and time-dependent release of ENMs. The probabilistic SSD approach makes it possible to include all available data to estimate hazards of ENMs by considering the whole range of variability between studies and material types. The risk-assessment approach is therefore able to handle the uncertainty and variability associated with the collected data. The results of the present study provide a scientific foundation for risk-based regulatory decisions of the investigated ENMs. Environ Toxicol Chem 2018;37:1387-1395. © 2018 SETAC.

Dynamics of bisphenol A (BPA) and bisphenol S (BPS) in the European paper cycle: Need for concern?

Bisphenol A (BPA) is an industrial chemical used as an additive in conventional point-of-sale thermal paper receipts. Due to BPA being an endocrine disruptor and a substance of very high concern, the European Union (EU) has proposed to ban its use in thermal paper from 2020. Potential similarities in toxicological profiles have raised concerns that the use of bisphenol S (BPS) as a substitute for BPA may result in yet another situation of a problematic chemical being distributed in consumer products. This study provides a comprehensive evaluation of the current knowledge of BPA and BPS use in thermal paper and, based on dynamic material and substance flow modeling, quantifies potential effects of the BPA ban on future BPA and BPS flows within the European paper cycle. Based on available data and the modeling of BPA and BPS flows, approximately 200 t of BPS are estimated to be present in the current European paper cycle. The modeling further demonstrated that by substituting 50% of BPA, BPS amounts in the European paper cycle would increase more than fivefold over a modeling period of 60 years. In the same time, more than 90 t of BPA would still be circulated in European paper products. BPA alternatives other than BPS should receive additional attention, as very limited quantitative data currently exist. The results of this study quantitatively demonstrate that chemical bans alone are not sufficient to ensure clean material cycles, and so the effective regulation of potential substitutes needs to be implemented in parallel.

Quantifying potential anthropogenic resources of buildings through hot spot analysis

This study estimates the amount of urban ores in Taipei City between 1965 and 2014 by analyzing data of the buildings through statistics and geographical information systems (GIS). Hot spot analysis (HSA) is introduced to assess the location of resources. Our results show that up to the year 2014, 186 Mton of construction materials were accumulated in Taipei, and the per capita total building material stock was 68 ton. In the short term, the hot spots with development potential are Da’an (Zone I) and Zhongshan (Zone II) Districts in Taipei City. Zone I (0.1 km2) stored 180 kton of materials; while Zone II (0.6 km2) stored 119 kton of materials. This study provides quantitative data on urban ores with high spatial and temporal resolution for enhancing material recycling planning and management. Material stocks could then combine with the material flow to build a dynamic material flow model for assessing the quantity of extractable urban ores, and the feasibility of exploitation in the future.

Modeling the fate and end-of-life phase of engineered nanomaterials in the Japanese construction sector

To date construction materials that contain engineered nanomaterials (ENMs) are available at the markets, but at the same time very little is known about their environmental fate. Therefore, this study aimed at modeling the potential fate of ENMs by using the example of the Japanese construction sector and by conducting a dynamic material flow analysis. Expert interviews and national reports revealed that about 3920–4660 tons of ENMs are annually used for construction materials in Japan. Nanoscale TiO2, SiO2, Al2O3 and carbon black have already been applied for decades to wall paints, road markings or concrete. The dynamic material flow model indicates that in 2016 about 95% of ENMs, which have been used since their year of market penetration, remained in buildings, whereas only 5% ended up in the Japanese waste management system or were diffusely released into the environment. Considering the current Japanese waste management system, ENMs were predicted to end up in recycled materials (40–47%) or in landfills (36–41%). It was estimated that only a small proportion was used in agriculture (5–7%, as ENM-containing sewage sludges) or was diffusely released into soils, surface waters or the atmosphere (5–19%). The results indicate that ENM release predominantly depend on their specific applications and characteristics. The model also highlights the importance of adequate collection and treatment of ENM-containing wastes. In future, similar dynamic flow models for other countries should consider, inasmuch as available, historical data on ENM production (e.g. like declaration reports that are annually published by relevant public authorities or associations), as such input data is very important regarding data reliability in order to decrease uncertainties and to continuously improve model accuracy. In addition, more environmental monitoring studies that aim at the quantification of ENM release and inadvertent transfer, particularly triggered by waste treatment processes, would be needed in order to validate such models.

Dynamic analysis of European copper flows

A dynamic material stock & flow model for the European Union (EU28) is presented and discussed. Detailed results are provided for the period 1990–2014 including trade flows, while the modelling period extends from 1910–2014 using extrapolation based on economic growth in order to better depict the build-up of long-term stocks (especially building & infrastructure). Model results indicate a total copper stock in use of approx. 82 million tonnes of copper in 2014, with a net addition to stock on the order of 500 thousand tonnes. Comparison with different country studies reveals different dynamics in Eastern and Western Europe. Eight recycling indicators are presented for 2014 and the latest 10-year period. In 2005–2014, ≈50% of copper refined and remelted in the EU was from secondary sources (recycling input rate), ≈50–60% of which were post-consumer (old) scrap (end of life recycling input rate 25–30% depending on the assumed composition of traded scrap). Uncertainties in the input parameters were explored using a stochastic method with 10.000 simulation runs.

Empirical Dynamic Material Flow Model for Tungsten in the USA

SummaryMultivariate polynomial regression (MPR) analysis was implemented to develop a nonlinear dynamic material flow model (DMFM) of tungsten in the United States for the years 1975–2000 without assumptions for lifetime distributions within reservoirs. Two external economic factors, the Consumer Price Index and the Industrial Production Index, were included as possible exogenous variables. Six types of vector time‐series models were developed using multilinear, simple interaction, and MPR models, each with and without the exogenous economic variables. The DMFMs developed in this work make one‐step‐ahead predictions. That is, the material flows in a given year were predicted using flows and exogenous variables from previous years. In contrast to approaches that utilize assumed lifetime distributions for material within reservoirs, such as the Weibull distribution, the approach used here is completely data driven. MPR models produced statistically better results than linear models for all 13 flows that were modeled. Four of these models used simple interaction terms (which we call linear interaction terms), and two of these incorporated exogenous variables. The other nine models utilized higher‐degree terms with interactions (called multivariate polynomial terms), and two of these incorporated exogenous variables. We conclude that nonlinear vector time series are capable of identifying complex relationships among material flows and exogenous variables. An understanding of these relationships has potential for managing, conserving, and/or forecasting the use of a resource.

Envisioning Nano Release Dynamics in a Changing World: Using Dynamic Probabilistic Modeling to Assess Future Environmental Emissions of Engineered Nanomaterials.

The need for an environmental risk assessment for engineered nanomaterials (ENM) necessitates the knowledge about their environmental emissions. Material flow models (MFA) have been used to provide predicted environmental emissions but most current nano-MFA models consider neither the rapid development of ENM production nor the fact that a large proportion of ENM are entering an in-use stock and are released from products over time (i.e., have a lag phase). Here we use dynamic probabilistic material flow modeling to predict scenarios of the future flows of four ENM (nano-TiO2, nano-ZnO, nano-Ag and CNT) to environmental compartments and to quantify their amounts in (temporary) sinks such as the in-use stock and ("final") environmental sinks such as soil and sediment. In these scenarios, we estimate likely future amounts if the use and distribution of ENM in products continues along current trends (i.e., a business-as-usual approach) and predict the effect of hypothetical trends in the market development of nanomaterials, such as the emergence of a new widely used product or the ban on certain substances, on the flows of nanomaterials to the environment in years to come. We show that depending on the scenario and the product type affected, significant changes of the flows occur over time, driven by the growth of stocks and delayed release dynamics.