Dynamic Material Flow Analysis Research Articles

Mapping Plastic and Plastic Additive Cycles in Coastal Countries: A Norwegian Case Study.

The growing environmental consequences caused by plastic pollution highlight the need for a better understanding of plastic polymer cycles and their associated additives. We present a novel, comprehensive top-down method using inflow-driven dynamic probabilistic material flow analysis (DPMFA) to map the plastic cycle in coastal countries. For the first time, we covered the progressive leaching of microplastics to the environment during the use phase of products and modeled the presence of 232 plastic additives. We applied this methodology to Norway and proposed initial release pathways to different environmental compartments. 758 kt of plastics distributed among 13 different polymers was introduced to the Norwegian economy in 2020, 4.4 Mt was present in in-use stocks, and 632 kt was wasted, of which 15.2 kt (2.4%) was released to the environment with a similar share of macro- and microplastics and 4.8 kt ended up in the ocean. Our study shows tire wear rubber as a highly pollutive microplastic source, while most macroplastics originated from consumer packaging with LDPE, PP, and PET as dominant polymers. Additionally, 75 kt of plastic additives was potentially released to the environment alongside these polymers. We emphasize that upstream measures, such as consumption reduction and changes in product design, would result in the most positive impact for limiting plastic pollution.

Anthropogenic cycles of praseodymium in China: 2000–2020

Praseodymium (Pr) is one of critical rare earth elements (REEs), which is widely used in clean energy technologies and home appliances. With the increasing demand of renewable energy, it is necessary to uncover the features of Pr stocks and flows through its whole life cycle. China is the largest REEs supplier in the world, but its Pr stocks and flows remain unclear. Therefore, this study investigates the anthropogenic Pr cycle in China for the period of 2000–2020 by applying dynamic material flow analysis. The results show that a total of 176 Gg Pr flowed into the Chinese anthropogenic system over the past two decades. Pr supply reached 10.8 Gg in 2020, while Pr demand reached 9.2 Gg in 2020, respectively. The top three Pr consumption fields were wind turbines (2.5 Gg), refrigerators (431 Mg), and electric vehicles (403 Mg) in 2020, with annual growth rates of 40%, 32%, and 86% during the study period, respectively. The largest in-use Pr stock came from wind turbines (with a figure of 18.8 Gg) in 2020, followed by air conditioners (5.5 Gg) and wash machines (3.2 Gg). The largest end-of-life flow came from air conditioners in 2020, with a figure of 847 Mg. Based on these results, three policy recommendations are proposed, including stable Pr supply, appropriate Pr recycling and recovery, and synergetic management with neodymium.

Quantifying provincial in-use stocks of rare earth to identify urban mining potentials in the Chinese mainland

Recycling of rare earth elements (REE) can help to offset the increasing demand for REE minerals and enhance the diversification of the REE supply chain. The development of low-carbon technologies, such as new energy vehicles and wind turbines has expedited the accumulation of REE as “urban mines”. This trend offers prospects for the progress of REE recycling initiatives targeting end-of-life products. This study conducts a dynamic material flow analysis (combined top-down and bottom-up method) of nine products containing NdFeB permanent magnets (their scrap is regarded as the most important secondary resource of rare earth) in the Chinese mainland at a provincial level to identify end-of-life products and provinces with high urban mining potentials. Results indicate that e-bikes, wind turbines, and air conditioners have the most significant REE recycling potentials in the Chinese mainland. Provinces with large populations and robust economies, such as Guangdong and Jiangsu, exhibit greater potential for REE recycling. This study illustrates significant provincial disparities in the end-of-life recycling potentials of REEs in the Chinese mainland and highlights the significance of provincial-level assessments of urban mining potential in the planning of the REE recycling industry.

Critical material requirements and recycling opportunities for US wind and solar power generation

AbstractThe deployment of renewable energy generation technologies, driven primarily by concerns over catastrophic climate change, is expected to increase rapidly in the United States. Rapid increases in the deployment of wind and solar energy will translate to increases in critical material requirements, causing concern that demand could outstrip supply, leading to mineral price volatility and potentially slowing the energy transition. This study presents a detailed demand‐side model for wind and solar in the United States using dynamic material flow analysis to calculate the requirements for 15 elements: Cr, Zn, Ga, Se, Mo, Ag, Cd, In, Sn, Te, Pr, Nd, Tb, Dy, and Pb. Results show that transitioning to a completely decarbonized US energy system by 2050 could require a five‐to‐sevenfold increase in critical material flow‐into‐use compared with business as usual (BAU), with some materials requiring much larger increases. Rare earth elements (REEs) could require 60–300 times greater material flows into the US power sector in 2050 than in 2021, representing 13%–49% of the total global REE supply. Te requirements for reaching net zero by 2050 could exceed current supply, posing challenges for widespread deployment of cadmium‐telluride solar. We also investigate several strategies for reducing material requirements, including closed‐loop recycling, material intensity reduction, and changing market share of subtechnologies (e.g., using crystalline silicon solar panels instead of cadmium telluride). Although these strategies can significantly reduce critical material requirements by up to 40% on average, aggressive decarbonization will still require a substantial amount of critical material.

Ensuring the sustainable supply of semiconductor material: A case of germanium in China

The semiconductor industry relies on the sustainable supply of critical mineral resources, such as Germanium (Ge), a key metal used in making electronics, fiber cables and solar cells. However, since Ge is a companion element, its primary production is constrained by the availability of host minerals such as zinc and coal. As such, its recycling is challenging since both recycling networks and technologies are still in its early infancy. There are increasing concerns on how to meet with the future demand for Ge due to its limited supply. This study aims to uncover the metabolic characteristics of the Ge cycle in China for the period of 2002–2021 from a whole life cycle perspective by employing a dynamic material flow analysis. The results show that China's demand for Ge had increased from 19.16 tons in 2002 to 85.87 tons in 2021. Fiber cables and infrared optical instruments consumed the most Ge resource, accounting for 54.59% and 36.76% of the total Ge consumption, respectively. The in-use Ge stock had increased more than 40 folds, implying a substantial potential for future recycling. The majority of Ge was extracted from coal ash and zinc concentrates, with figures of 1086.92 tons and 585.27 tons respectively, while only 13.45 tons of Ge were recovered from those end-of-life products. Furthermore, the Ge loss reached 1586.31 tons at the production stage. The Ge stock in those intermediate products has gradually decreased. The cumulative Ge export amount contained in various products was 655.64 tons, mainly dominated by intermediate products, while the share of final products increased in recent years. Based on these findings, several policy recommendations are proposed, including improving Ge production efficiency and expanding Ge supply sources, establishing a comprehensive Ge recycling system, and upgrading the entire Ge industrial chain. These policies can help better cope with the challenges that the global semiconductor supply chain is facing.

Mapping the evolution of manganese flows and stocks in China from 2000 to 2021

Manganese is a strategic metal that has been widely applied in the steelmaking industry and the emerging energy batteries industry. China is the largest manganese importer and consumer, but the critical features of its manganese metabolisms, including its supply and demand, trade, and waste management, remain unclear. By applying dynamic material flow analysis (DMFA) method, this research investigates the evolution of China’s anthropogenic manganese flows and stocks during the period of 2000 to 2021. We found that the demand for manganese had increased almost tenfold in China from 2000 to 2021, mainly used for steelmaking, while the surging demand for manganese in energy batteries had gradually increased. However, China highly relied on importing manganese concentrates due to its limited manganese resources. The cumulative in-use manganese stocks also increased by tenfold and reached approximately 168 million tons (Mt). In addition, manganese flow from the end-of-life (EoL) final products reached 12 Mt in 2021, but few of them were recycled, implying a huge recycling potential. These findings provide valuable insights to prepare more appropriate manganese resource management policies, such as improving domestic mining technologies, enhancing manganese recycling, and diversifying the supply of manganese resources, so that the overall manganese resource efficiency can be improved.

Uncovering the key features of platinum metabolism in China during 2001–2022: A dynamic material flow analysis

Platinum is a critical mineral resource and has been called the “vitamin” of the technology industry as it is widely utilized in diverse fields such as automobiles, petroleum, chemicals, medicine, jewelry, and electronics. The demand for platinum is increasing, but its reserve is limited, especially in China, a major platinum user in the world. This study aims to track the platinum cycle in China for the period of 2001–2022 by employing dynamic material flow analysis so that the key features of platinum metabolism in China can be identified. Our results show that the total production of domestic platinum mining accounted for only 1.27% of the national platinum supply. China had to import platinum resource to meet with its increasing demand. The jewelry sector contributed the largest platinum consumption due to the preference of the Chinese consumers. There are two recycling routes for all the retired platinum-containing products, including both closed-loop and open-loop routes. Also, the total illegal imported platinum scraps reached 131.27 tons, accounting for 47.57% of the total open-loop recycled platinum. China's platinum in-use stocks increased from 44.23 tons in 2001 to 824.49 tons in 2022. As a result, the end-of-life platinum scraps increased from 0 tons in 2001 to 65.83 tons in 2022. In addition, China primarily imported platinum semi-finished products to meet its domestic demand, but mainly exported platinum scraps and finished products to other countries. Based on these research findings, policy recommendations are proposed by considering the Chinese realities, covering political, technological, and industrial cooperation dimensions. The results of this study provide valuable insights to those decision makers so that they can prepare more effective platinum resource policies.

A dynamic model for estimating the long-term need for repairs and renovations in residential buildings

ABSTRACT Reaching sustainability targets requires a holistic understanding of the different dimensions of residential building stock development. This paper aims to provide a solid and transparent approach for modelling residential building stock development with a focus on the long-term need for repairs and renovations. The modelling approach is based on Dynamic Material Flow Analysis (MFA) and the model is constructed using comprehensive Finnish statistics. Still, it is widely applicable to different geographical locations and modifiable for various purposes. The main contributions to the previous literature are the incorporation of empirical building mortality analysis and rehabilitation degree model in the MFA modelling framework. The model is demonstrated by modelling the development of Finnish residential building stock from 2020 to 2050. The annual average need for renovation from 2020 to 2050 is 4.1 million residential square metres (1.8% percent of the entire housing stock), equalling to annual investments of some 7.8 billion euros. However, the results revealed notable geographical differences between municipality categories. The results also suggest that the proportion of renovations in the total construction market is increasing while the volume of new housing construction is decreasing. The modelled results are in line with the Finnish Long-Term Renovation Strategy 2020–2050.

Mapping Chinese plastic flows from 2001 to 2040 based on dynamic probabilistic material flow analysis and scenario projection

Plastic waste management, deeply intertwined with our economy, presents a global challenge. Plastic pollution pervades both aquatic and terrestrial ecosystems worldwide. In a vast country like China, establishing a comprehensive plastic flow regime that accounts for socioeconomic disparities between urban and rural areas is essential for effectively reducing s plastic waste. This study aims to map the life-cycle of China's plastic flows from 2001 to 2040, distinguishing between urban and rural sources, through integrating dynamic probabilistic material flow analysis with scenario analysis. The results indicate that from 2001 to 2020, cumulative plastic waste generation was 1001 ± 14.6 million tonnes (Mt), with a higher proportion originating from urban areas (706 ± 10.3 Mt) compared to rural areas (218 ± 3.2 Mt). The rate of increase in mismanaged plastic wastes (MPWs) in rural areas outpaced that in urban areas, peaking in 2016, five years after the peak in urban areas. Consequently, the cumulative total of rural MPWs, including littering (103.5 ± 2.0 Mt) and open dumping (74.8 ± 1.5 Mt), was higher than that in urban areas (littering: 83.0 ± 4.0 Mt; open dumping: 70.3 ± 1.4 Mt). The scenario analysis forecasts a reduction of 96.5 ± 0.4 % and an 83.0 ± 2.1 % in MPW generations in urban and rural areas by 2040, respectively, if all interventions are implemented. However, strategies like reuse&recycling and reduce&substitute are less effective in rural areas compared to urban areas. Therefore, we recommend establishing a collection system with both penalties and incentives to reduce rural MPWs.

Revealing the long way towards lead-free plastic in China through dynamic material flow analysis of lead salt heat stabilizers in PVC products

The use of lead salt heat stabilizers (LHSs) in plastics are restricted or even prohibited owing to their high toxicity. However, little information is available on its industrial metabolism. A dynamic material flow analysis of LHSs indicates that China consumed 2952 kt LHSs between 1958 and 2020. Moreover, at present, 1020 kt of these is being used in polyvinyl chloride (PVC) products, 1007 kt is in landfills, and 681 kt is in the environment. For China to realize lead-free primary plastics by 2040, 2050, and 2060, the LHSs consumption should be reduced by at least 13 %, 10 %, and 9 % annually, respectively. Certain LHSs would gain new life with PVC recycling. Therefore, approximately 30 years would be required for LHSs to disappear completely after their use is stopped. With improvements in the plastic recycling rate, it is necessary to use chemical recycling and other methods to separate the hazardous additives such as LHSs and reduce the circulation of toxic substances.

Tracking two decades of global gallium stocks and flows: A dynamic material flow analysis

Gallium (Ga) has recently garnered significant attention as a crucial byproduct element due to its crucial role in advancing low-carbon technologies and its globally imbalanced supply-demand. Understanding the global Ga flows and stocks can contribute to discovering ways to mitigate potential supply risks. In this study, we applied a material flow analysis to map the global Ga cycle from 2000 to 2021. Our results reveal the following results: (1) Over the past two decades, a cumulative 15.3% (313240.8 tons) of the total Ga reserves has been consumed through host metals (i.e., bauxite and zinc ores) mining. However, affected by actual demand, only 5549.7 tons of Ga have been extracted. Moreover, China has gradually become the dominant supplier of primary Ga globally, relying on its robust alumina industry. (2) The consumption pattern of global Ga is becoming increasingly complex. Driven by the diffusion of low-carbon technologies, primary Ga consumption has grown from 101 tons in 2000 to 432 tons in 2021. With a low material efficiency, only 2143.4 tons of Ga ultimately enter final products from semi-products. (3) The global Ga stock reached 956.7 tons in 2021 with significant recycling potential. However, commercial recycling systems were not established, and Ga resources in end-of-life (EoL) final products are mostly wasted. Given the anticipated growth of Ga demand, more coordinated efforts among different regions to promote technological innovation and improve recycling and circularity rates are urgently needed to ensure global Ga supply and a shared green future.

Tracking the evolution of niobium cycle in China from 2000 to 2021: A dynamic material flow analysis

Niobium has been classified as one critical metal due to its wide applications in both fundamental and strategic industries. However, niobium resource is limited and unevenly distributed. China is the biggest niobium consumer and the demand for niobium will continue to increase due to its rapid urbanization and industrial development. This study aims to uncover the key features of niobium metabolism in China during 2000–2021 by employing a dynamic material flow analysis method. Our results show that both niobium flows and stocks experienced fast growth in China and the domestic demand for finished niobium products was highly concentrated. Moreover, China mainly relied on importing primary niobium resources from Brazil and Canada, while exporting semi-finished niobium products to Korea, Vietnam, Indonesia, and India. Several policies are then proposed by considering the Chinese realities to improve the utilization efficiency of niobium resources and secure its sustainable supply.

Multinational dynamic steel cycle analysis reveals sequential decoupling between material use and economic growth

Decoupling material use from economic growth is a prerequisite for alleviating the adverse effects of anthropogenic material use and achieving the Sustainable Development Goals. In this study, we combine dynamic material flow analysis with decoupling analysis to examine the relationship between the iron and steel cycle and economic growth in 23 industrialized countries from 1860 to 2018. Specifically, we employ both the quadratic and asymptotic functions to fit the relationship of per capita steel flow/stock indicators at six life cycle stages, including domestic production and apparent consumption of iron ore, pig iron, crude steel, finished steel, and fabricated steel, as well as in-use stock, against per capita GDP. A sequential decoupling between steel flow/stock indicators and GDP growth along the iron and steel cycle is evident. The historical dynamics of the comparative advantage of material flow indicators depict the wave-like geographic diffusion of industrialization. The mechanisms underlying the evolution of material-economy relationship can be attributed to resource endowments, industry policies, trade effects, and lock-in effect of in-use stock. Understanding this phenomenon can facilitate policy-making to promote dematerialization and improve material efficiency in developing countries.

The Trade-Off between Extended Lifetime and Resource Utilization Efficiency - a Critical Analysis of Battery Second-Use Concepts Using Materials Flow Analysis

Sustainability and environmental concerns have recently led to heavy investment in the electrification of transport. A major implication of this transition is a surge in demand for batteries, the state-of-the-art energy technology for electric vehicles. While electric vehicles are locally free of emissions, battery production and end-of-life management still challenge its status as an economically, socially, and environmentally sustainable technology. Among these challenges are the globally unequal distribution of raw materials and associated geopolitical, supply and trade-related concerns as well as the high costs and environmental risks of batteries’ waste management. Furthermore, landscape disruption, biodiversity loss, and concerns over child labor and other human rights abuses haunt the mining of raw materials.The circular economy promises to remedy many of these issues, by essentially allowing economic growth without the consumption of raw materials. It has enormous potential for the European Union in particular, as it has a growing trade deficit of raw materials due to a lack of resource deposits on the continent. Therefore, independence from them is expected to boost its international competitiveness. Besides reducing raw material dependence and thus supply risks, the circular economy promises to stimulate business model and product innovation, to meet the demands for recyclable and more durable products as well as recycling goals, further strengthening competitiveness.In the case of electric vehicles, recycling processes have been established to allow the regeneration of battery-grade raw materials from batteries. Furthermore, models of extending the battery’s life cycle by applying it in a secondary application with less demanding energy and power requirements have recently been proposed, termed “second use”. This delays the point in time when a battery is recycled. Materials-break-even-points (BEP), the points in time at which an economy can achieve independence from raw materials and thus reach circularity, can be a tool of analysis for the overall effect of this delay. Second use increases the duration until the BEP, while at the same time reducing the annual demand for primary raw materials. Despite the shift in BEP, it is frequently argued that the extended battery lifetime and the reduction in primary materials demand improve resource utilization. We argue, however, that second use could have undesirable side effects. This is because due to the capacity and voltage fade occurring over a battery’s lifespan and the improvements in material efficiency through advances in research and development over time, the average amount of raw material required for the storage of one unit of energy increases relative to a scenario where the battery is recycled earlier. Hence, the overall amount of material invested in the circular economy would be larger in a scenario with second use compared to a scenario without second use. Depending on the battery technology in question and thus the materials involved, this trade-off between the amount of material invested in the economy and the use span of a battery could play out differently with respect to economic, social, and environmental effects.In this work, this trade-off is investigated for a scenario involving different shares of LFP-based lithium-ion batteries, NCX-based lithium-ion batteries, and other technologies, with a focus on the raw materials Ni, Co and Li. Technology-specific scenarios are investigated, as different technologies require different raw materials, impacting the material flow rate over time. Furthermore, different technologies exhibit a varying degree of voltage and capacity fade over their lifetime, thus affecting the resource utilization efficiency in a second-use scenario. To this end, dynamic material flow analysis is applied, and the societal, economic, and ecological consequences of our findings are discussed from a critical perspective.The insights provided by this analysis are first and foremost a contribution toward understanding the principles that determine the long-term resource efficiency of a battery circular economy. These principles are vital for policymakers when envisaging political goals and incentive schemes for the transition toward a circular economy. The findings are also vital for actors from the battery and automotive industry when developing end-of-life strategies for electric vehicle batteries, as ensuring the most efficient use of battery raw materials improves resource availability and minimizes their products' environmental and societal impact.

Towards a Circular Economy of Lithium-Ion Batteries – Is a Fast Ramp-up of Recycling and Circularity Sustainable?

With the rapidly growing demand for lithium-ion batteries (LIBs) in electric vehicles (EV) major global challenges for policymakers and companies arise. Global production and supply chains of battery materials increasingly account for environmental issues accompanied by social problems of raw material mining (e.g., for cobalt in DR Congo) and recent highly fluctuating raw materials prices. To face these problems, policymakers and companies are pushing for circular economy strategies for battery supply chains to guarantee a sustainable supply of critical raw materials such as lithium, cobalt, and nickel, and to integrate used batteries back into the value chain by recycling or reuse. But reaching a full circular economy early does not translate into improved sustainability at the same time. A circular economy of batteries in EVs is fully developed once the demand for raw materials in EV batteries is completely covered by recycled materials, the break-even points (BEPs) of a circular economy. At this stage, regional independence from primary raw materials with critical production and supply chains is achieved.In this study, a critical perspective on the pushing for strategies to reach circular economy of EV batteries early is taken. Within three steps it is shown, (1) when the circular economy is realized on a regional level by reaching BEPs, (2) how to accelerate reaching these individual BEPs for battery materials through different scenarios, and (3) what this acceleration scenarios implies in terms of a sustainable global production of battery materials via mining and transportation compared to reuse and recycling.In the first step, this numerical analysis focuses on identifying the BEPs of lithium, cobalt, and nickel for EV batteries in key regions, namely Europe, the US and China, by using a dynamic material flow analysis (MFA). For this purpose, the life cycle of a battery is considered and analyzed in a circular economy approach via production, EV life, secondary application (re-use) and recycling. The results show that China is the first region to achieve BEPs for Co and Ni in the 2040s while focusing on LFP as the main battery technology in the upcoming decades, followed by Europe and the U.S. Compared to China, EV battery technologies in Europe and the USA are dominated by NMC and NCA leading to later BEPs for cobalt and nickel. Generally, cobalt will be the first metal to achieve BEPs, while the secondary coverage of lithium poses a major future global challenge.Second, based on a sensitivity analysis of the model parameters with the highest impact on the BEPs, different scenarios of parameter adaptions are presented which lead to potential earlier achievement of the BEPs in Europe, the USA and China (shift scenarios). These scenarios include early full electrification of car sales, no secondary application of EV batteries, reduction of EV battery sizes in time, shorter lifespan of batteries in EVs and high production scrap rates. The results show that each of the five shift scenarios has a different impact on accelerating reaching the BEPs in each region for the individual raw materials.Third, in each shift scenario, the necessary mining and production amount of primary EV battery materials until reaching the BEPs are analyzed. Although achieving BEPs earlier by applying the shift scenarios seems beneficial, the results indicate that more primary raw materials must be produced annually until reaching the BEP under certain conditions, suggesting that more social and environmental problems linked to raw material mining and transportation would have to be tolerated. Therefore, a sustainable slow ramp-up of mines and recycling must be weighted individually against a fast ramp-up and, thus, against reaching a full circular economy early.This analysis and the model in general can help policymakers and companies to strategically decide whether and how to accelerate achieving certain BEPs for an early independence from primary raw materials. However, by taking a critical perspective here, it is shown that accelerating the transition towards circular economy by reuse and recycling can be accompanied by intensifying temporary sustainable issues of raw material mining and transportation.

Phosphorus Utilization Efficiency and Status of Phosphorus Reuse in China from 1990 to 2019

Phosphorus (P) is an essential element for supporting our life and is a non-renewable resource. This study applied dynamic material flow analysis to elucidate the phosphorus flow characteristics in China over the period from 1990–2019. Based on this, we developed a P resource efficiency index system and further explored the potential reasons for the changes in different areas by analyzing the inflow, outflow, and reuse of P in various modules. Results show that the phosphorus utilization efficiency (PUE) in crop planting increased from 63% in 1990 to 72% in 2019, while this figure in feeding livestock increased from 35% in 1990 to 42% in 2019 due to the utilization of straw. The figure in aquaculture remained low at 9% in 2019. The total P amount used for human consumption increased to 2562 Gg in 2019 due to changes in dietary habits, and the overall P recycling rate (PRR) for various human activities jumped to 58% in 2019. Based upon these results, several policy suggestions are proposed from governance, technology, and economic instruments perspectives.

Environmental impact of biodegradable and non-biodegradable agricultural mulch film: A case study for Nordic conditions

PurposeBiodegradable mulch film is considered an environmentally friendly alternative to non-biodegradable-based mulch film for agricultural use. The purpose of this study is to compare the environmental impact of non-biodegradable mulch film to biodegradable mulch films for use in Nordic conditions, including assessing their plastic pollution potential.MethodsA life cycle assessment was conducted to calculate the potential environmental impacts of the films, while the plastic pollution potential was assessed with a dynamic material flow analysis, considering degradation over time and fate to various environmental compartments. The plastic pollution potential was based on empirical degradation data in Nordic conditions.Results and discussionThe results of the LCA and MFA analyses show that the use of non-biodegradable material in Nordic conditions leads to the lowest environmental impacts and pollution if it is fully collected after use. In fact, biodegradable mulch film leads to higher environmental impacts over its life cycle in most environmental impact categories. However, comparing environmental burdens from non-biodegradable and biodegradable mulch film is difficult due to the lack of data on biodegradable films. The results further highlight that biodegradable films will reach a dynamic equilibrium (a plateau phase) in soils in Nordic conditions between the degradation of old film and the application of new film, if not enough time is given for the films to entirely degrade. Farmers would need to apply biodegradable films with several years of interval, if the films should be entirely degraded.ConclusionsThis study supports the recommendations that biodegradable plastic has potential when used as mulch film, but these recommendations should be situation-specific, depending on farmers’ ability to handle the mulch film properly. The authors highlight that the LCA results are uncertain due to limited data availability and encourage the biodegradable plastic industry to be more transparent by making their LCIA data available.

Dynamic material flow analysis of wood in Germany from 1991 to 2020

Severe climate change and urgent climate action have raised concerns about wood. Overharvesting and increased wood waste are putting immense pressure on sustainable forest management and the global carbon budget. In Germany, a vital wood supplier and user in Europe, the wood supply chain's production, consumption, trade, and recycling have been insufficiently investigated. To tackle this challenge, we conducted a comprehensive dynamic wood flow analysis from 1991 to 2020. Approximately 2143 million cubic meters of standing timber were felled in German forests over the past three decades, with 80% used for materials and 20% for energy purposes. Wood flow patterns were susceptible to market demand and forest disturbances like drought, storms, and insect infestations. The storm in 2007 left a notable impact, leading to the highest figures ever recorded for various wood products. Notably, the net forest carbon sink, carbon storage in forest products, and energy substitution effect (replacing fossil energy with wood) reached 160, 332, and 343 million tons of carbon, respectively. However, the transition to renewable energy, wooden buildings, and wood and paper packaging demands further strains the wood supply chain. To promote sustainable forest management and achieve climate neutrality, we propose potential strategies for consideration.

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

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

Evaluating rare-earth constraints on wind power development under China's carbon-neutral target

China proposed a target to achieve carbon neutrality before 2060. Wind power is crucial for mitigating climate change and achieving carbon neutrality. However, its development depends on the potential constraints of rare-earth elements. Therefore, first projecting the rare-earth demand for wind power equipment in the context of achieving carbon neutrality and identifying potential obstacles are necessary. However, the carbon-neutral pathway for China's power sector is unclear, let alone the corresponding rare-earth demand. Consequently, this study explores a potential cost-effective carbon-neutral pathway for China's power sector and quantifies the demand for rare-earth elements used for producing wind power equipment under different pathways, by integrating dynamic material flow analysis and a national energy technology model. The results showed that the rare-earth supply may be inadequate for wind power development in terms of achieving carbon neutrality in China, especially for dysprosium and terbium. To neutralise the carbon emissions of China's power sector, the cumulative rare-earth demand during 2021–2060 would be 222–434 kt, of which at most 1/3 could potentially be obtained by circular usage from end-of-life wind turbines. However, the existing low secondary recovery rate of rare-earth elements makes the available circular amounts very small. Shifting to a wind power market dominated by direct-drive turbines may increase the cumulative rare-earth demand by up to 34 %. Without material intensity reduction for the wind power technologies, an additional 38 % demand for rare-earth elements will occur, exacerbating the risk of shortage.