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Improving resource efficiency (RE) is an important objective of the Sustainable Development Goals. In this study we find a strong exponential relationship between economic complexity index (ECI) and RE of countries. ECI measures the level of accumulated knowledge of a society enabling the products it makes. The relationship between ECI and RE is stronger for primary material importers and countries with stable institutions. Assessing a country's level of ECI also allows the outlook of future RE trends. We explain how ECI influences RE at the product level by establishing the product space for each country and by defining core products that contribute to a high product complexity index, high RE (i.e., unit price) and promising expansibility (i.e., core number), which indicates the potential to produce more advanced products in the future. Policies that improve economic complexity and invest in core products seem to be a priority to achieve sustainable development.

While electric vehicles (EVs) have been promoted for green consumption, improper or inadequate management of end-of-life (EOL) EV batteries, as the current practice, compromises the benefits of EV adoption. This study aims to contribute to both theoretical research of material flow analysis and timely management of EOL EV batteries at various geographic scales (i.e., national, state, and county). Theoretically, this study tests two battery lifespan scenarios (i.e., constantly at 3–8 years and dynamically increasing over time), three discard probability functions (i.e., uniform, truncated normal, and Weibull), and three EV sale projections (i.e., low, moderate, and high). Results show that the short-term EOL volume (by 2025) can be particularly sensitive to the lifespan parameter. The long-term estimates involve most uncertainties related to the EV market penetration. Various discard probability functions generally derive similar results. In practical terms, the results suggest that necessary infrastructure for proper EOL EV battery management is needed sooner than the public may have perceived. This study urges for regional planning that incorporates both temporal and spatial considerations. To illustrate an example of regional solutions, this study adopts empirical data in California to simulate and spatially match EOL EV battery clusters and the renewable energy facilities that can potentially reuse EV batteries as energy storage. Meanwhile, the spatial mis-match between the supply and demand, as can be the case in other regions, calls for region-wide coordination in terms of both infrastructure development and transportation planning.

China is accelerating automotive electrification to address the pressing oil shortage and environmental pollution issues. Automotive electrification can be achieved through four different major technology pathways: hybrid electric vehicles, plug-in hybrid electric vehicles, battery electric vehicles and fuel cell electric vehicles. These pathways all heavily rely on the use of critical mineral resources, such as rare earth elements (REEs). This study establishes different scenarios of the future technology mix and growth in automotive electrification in China by 2030 to predict the future demand of REEs associated with such scenarios. The widely applied Bass model is chosen to predict the future growth of these four technology pathways for electric vehicles under pessimistic, neutral and optimistic demand scenarios. Given the potential for technological advances, the effects of changes in the material intensity and component substitution are considered to effectively reflect future demand changes. Accordingly, the REE demand associated with the four technology pathways from 2018 to 2030 is estimated. The highest demand for REEs in automotive electrification will reach 315 thousand tons, accounting for 22% of global production during the prediction period. Specifically, the demands for Nd, Dy, Ce, Pr, and La will account for 51%, 20%, 12%, 9.5%, and 7.7% of the total demand, respectively. Moreover, the contrast between the supply and demand of Dy and Pr will be extremely large, and these elements will require more attention than others. For the successful development of automotive electrification in China, related policies and plans regarding the supplies of different types and quantities of REEs should be urgently established.

As a main destination for recycling, reuse and disposal of solid waste in the global circular economy, China has recently issued a new regulation on its imports, banning 24 types of solid waste in 4 categories, including waste plastics, unsorted scrap papers, discarded textile materials, and vanadium slags. Bans on additional types of solid waste will take effect soon. Here we discuss the possible profound effects of such policy changes on the global circular economy of solid waste. Recycling industries in developed countries will face challenges in the short run, due to their limited capacity and past reliance on exporting, but also opportunities in the long run. Furthermore, developing countries currently without stringent environmental regulations will likely become the new “pollution haven” of solid waste from developed countries and even emerging economies such as China itself. To truly reap the benefits from China's new policies which are originally designed for environmental sustainability and social justice, the global community needs to develop appropriate policy framework to prevent the unintended consequences.

Increasing material efficiency, or material productivity, is essential for decoupling resource depletion and associated environmental pressures from economic development. This paper reviews the historical evolution of indicators monitoring material efficiency, their underpinning methodologies and major findings in the past three decades. Early studies investigated the material-economy relationship through intensity of use (IU) of some selected single materials. Economy-wide material flow accounting (EW-MFA) established a standardized framework for aggregating overall material inputs into an economy. Consumption-based material footprint (MF) analysis extended the system boundary to cover global resource extraction along supply chains to satisfy final consumption. Studies on material cycles (MC), especially metal cycles, further helped trace all major life cycle stages of anthropogenic material use, with the capability to account for in-use stocks of materials and products. Impact-based indicators investigate the opportunities to reduce negative environmental, social and economic impacts of material use, which is the ultimate purpose of improving material efficiency. Monitoring material efficiency with different indicators might lead to very different conclusions regarding a society’s dependence on material and its dematerialization trend. We present a generalized framework for constructing all kinds of material efficiency/productivity indicators and make the case that election of indicators should be problem-oriented and policy-relevant.

Copper is ubiquitously used in buildings, infrastructure, transportation, machinery, and other products because of its high conductivity. Massive amounts of copper have accumulated in cities with rapid urbanization. However, the lack of detailed spatiotemporal information on copper stocks presents a challenge for waste management and resource recycling. Here, we took the Jing-Jin-Ji urban agglomeration in China, which has experienced rapid urbanization over the past few decades, as a case study to characterize the spatiotemporal patterns of in-use copper stock. The results showed that in-use copper stocks per capita had reached 61 kg in 2016, about 3.8 times the level it was in 1990. Buildings, electric power transmission and distribution systems, small passenger cars, industrial machinery, and air conditioners dominated the in-use stocks and thus, they were the main reservoirs of secondary resources. Significant economic and population growth stimulated a rapid increase in copper stocks, especially in the megacities (e.g., Beijing, Tianjin, Shijiazhuang, Tangshan, and Handan). Based on the scenarios of urbanization, we estimated that in-use stocks of copper per capita would continue to grow in the Jing-Jin-Ji urban agglomeration until saturation, and that the saturation level might be lower than that of developed countries. High population density was key to promoting copper resource utilization efficiency, particularly in the infrastructure sector. This critical information highlights the urgent need for developing compact cities to reduce the pressure caused by copper resource consumption in China.

The rapid economic development in emerging economies is deeply coupled with massive material use, which poses serious challenges to the environment. Thus, the desired transition towards sustainable society requires a more complete understanding of the interplay of material stock and economic development. To investigate how the productivity of materials evolves as the economy grows, we develop a modified Cobb-Douglas production function model by incorporating steel stock as one input factor and conduct a panel regression analysis based on China's provincial-level data from 1990 to 2016. Our empirical results indicate that steel stock plays a vital role, almost equivalent to labor and non-steel capital stock, in economic growth in China, and output elasticity of steel stock, which reflects its productivity, increases with economic development but might decline at a very developed stage. Potential factors leading to such variations in steel stock productivity are further explored by an extended model. It is found that industrialization and urbanization levels contribute positively to the output elasticity of steel stock while the existing stock level plays an opposite role. As industrialization and urbanization levels hit the upper limit when the economy matures, we predict that China's steel stock productivity will reach a plateau or start decreasing, depending on the future path of investment in materials.

Quantifying the changing patterns and determinants of material stocks (MS) is important for understanding the interplay between socioeconomic development and environment conservation, and for addressing the challenges in sustainable development. This paper conducts a MS accounting for 10 materials in 6 major infrastructures in Beijing, Tianjin and Shanghai, and probes into the driving factors behind the change within the 1978–2013 period through a logarithmic mean divisia index decomposition method. The results suggest that MS changes through a rapid enhancement in the 1980s, a steadily growth in the 1990s, and an acceleration after the 2000s. A relative decoupling phenomenon was detected in the development of economy and MS, which was largely caused by the decline of MS intensity. The policy implications include paying more attentions to the improvement of MS efficiency especially in buildings, substituting for less energy-intensive construction materials, controlling the extensive urban sprawl, and raising the population density.

Air quality has proven to be closely related to economic levels. China is a vast country with substantial economic level and air quality disparities among cities. Consequently, policy-makers face challenges in implementing regional collaborative governances. Here, we use the bivariate local indicator of spatial association (LISA) statistic to reveal the spatial heterogeneous relationship between local per capita GDP and nearby air quality, especially fine particulate matter (PM2.5). This study was conducted in 256 prefecture-level cities for the year 2015. The results show that 20, 28, 30, 28, and 187 cities were identified as the HpcgdpHpm2.5, LpcgdpLpm2.5, LpcgdpHpm2.5, HpcgdpLpm2.5, and ‘not significant’ typologies, respectively. Furthermore, LpgdpHpm2.5 cities are mainly located in the northern China, whereas HpcgdpLpm2.5 cities are mainly distributed in the Guangdong provinces. The underlying causes may be attributed to the differences in economic structures. We found that LpgdpHpm2.5 cities has approximate 60% more coal-fired power plants, 2.3 times iron and steel plants than those of HpgdpLpm2.5 cities, whereas the latter attracted 5.1 times as much investment capitals from foreign, Hong Kong, Macao and Taiwan as the former. This indicates the industries of HpgdpLpm2.5 cities have higher technology levels and lower emission intensities. Thus, policy makers should accelerate economic transformation, especially in Shandong, Hebei, and Henan provinces. Overall, our findings suggest that not only bivariate LISA statistic is a simple and useful approach to distinguish city typologies, but also provide the evidences for those cities responsible for air quality of adjacent cities.

Plastics have been playing a vital role in the industrialized economy, resulting in the growing amount of plastic waste and the surging attentions to plastics sustainability challenge. This is well reflected in the growing amount of submissions to and publications in Resources, Conservation, and Recycling on plastics, which made the editorial board decide to edit a Virtual Special Issue (VSI) on the “sustainable cycles and management of plastics” in 2018. The call for the VSI has attracted many submissions and twelve were accepted for publication. Together with several other relevant studies, we collected and summarized a total of 26 papers published in RCR mainly during 2019–2020 in this editorial. These papers mostly apply system approach and cover very wide topics such as material flows analysis and circular economy, life cycle assessment and eco-design, regional and global plastic emissions, and human consumption behavior. The whole collection of them offer a comprehensive view of the plastic waste challenges, as well as insights into achieving sustainability in plastic cycles and management. We believe these papers are helpful for government, industries, and individuals in exploring policy implications for building a more sustainable plastics system.

Tungsten is deemed a critical raw material by many nations, given its irreplaceable use in industrial and military applications. In particular, much concern has been drawn to China's high share in global tungsten supply. While various studies have focused on the criticality of tungsten, few have specifically explored how tungsten is produced, consumed, and traded. In this paper, the dynamic material flow analysis is applied to quantify China's annual tungsten cycle from 1949 – 2017. It is estimated that total tungsten mined from ores in China over the past 68-year period is ~2500 kilo-tons (kt). Among those, ~750 kt of tungsten has been exported to other countries, and around 970 kt tungsten is domestically consumed. It is noted ≈1720 kt has been lost from mining, production, and end-of-life stage, and merely ~130 kt has been recycled as end-of-life scrap. Our material flow analysis further refined China's tungsten dominance. Although China currently dominates the global production of tungsten, this dominance will not extend too far into the future given China's limited share of world tungsten reserves and its declining ore quality. Our trade flow analysis reveals that China imported ~35 kt of high value-added downstream tungsten products from outside manufacturers, whose mineral resource was originally imported from China. At present, China by itself is experiencing overcapacity issues in the primary production, which discourages the recycling of at end-of-life (EoL) stage and makes the EoL recycling rate only 10%. It is noted that the percentage of Chinese tungsten for domestic consumption has been increasing in the past few years. This highlights the need for systematic measures from stakeholders along the tungsten cycle to promote sustainable practices for efficient tungsten production, use, and recycling in China. Meanwhile, the results also suggest the importance of monitoring the criticality of tungsten and other critical minerals from a dynamic and material cycle perspective.

Millions of tonnes (teragrams) of plastic waste are traded around the world every year, which plays an important role in partially substituting virgin plastics as a source of raw materials in plastic product manufacturing. In this paper, global plastic waste trade networks (GPWTNs) from 1988 to 2017 are established using the UN-Comtrade database. The spatiotemporal evolution of the GPWTNs is analyzed. Attention is given to the country ranks, inter- and intra-continental trade flows, and geo-visual communities in the GPWTNs. We also evaluate the direct and indirect impacts of China’s plastic waste import ban on the GPWTNs. The results show that the GPWTNs have small-world and scale-free properties and a core-periphery structure. The geography of the plastic waste trade is structured by Asia as the dominant importer and North America and Europe as the largest sources of plastic waste. China is the unrivaled colossus in the global plastic waste trade. After China’s import ban, the plastic waste trade flows have been largely redirected to Southeast Asian countries. Compared with import countries, export countries are more important for the robustness of GPWTNs. Clearly, developed countries will not announce bans on plastic waste exports; these countries have strong motivation to continue to shift plastic waste to poorer countries. However, the import bans from developing countries will compel developed countries to build new disposal facilities and deal with their plastic waste domestically.

Dynamic stocks and flows analysis was applied to the anthropogenic aluminum cycle in Italy in order to detect and quantify metal flows and in-use stocks over the years 1947–2009. The model utilized a top-down approach, including data for production, consumption, loss, and trade flows of aluminum. Seven end-use markets were considered, namely buildings and construction, transportation, consumer durables, machinery and equipment, electrical engineering, containers and packaging, and miscellaneous appliance types. The results of this dynamic stocks and flows analysis model quantified the contemporary anthropogenic reservoirs (or in-use stocks) of aluminum at about 320 kg per capita, mainly embedded within the transportation and building and construction sectors. Cumulative in-use stock represents approximately 11 years of supply at current usage rates (about 20 Mt versus 1.7 Mt/year), implying significant potential for recycling in the future as this stock comes out of use. Flow analysis revealed that Italy imports mainly unwrought aluminum and exports final products, while the main material losses occur during alumina refining and collection of old scrap: specifically, containers and packaging have the highest old scrap generation rate, but for the lowest recovery rate (50%). Increasing support to collection of scrap and initiatives oriented to aluminum recovery specifically would allow Italy to increase its reliance on domestic material, and may also allow a decline of the country import-dependence on primary sources. The dynamic stocks and flows model created here provides a quantitative historical record of the aluminum required by Italian society during important periods of development and provides guidance for future decision-making around the use of domestic secondary resources.

This paper analyses the anthropogenic stocks and flows of aluminum in mainland China from 1950 to 2009 using time-series data for mining, production, fabrication, manufacturing, trade, and loss rates, and applies a dynamic top-down method to model scrap generation. Results show that growth rates of all flows increased from decade to decade, with 75% of most of the flows taking place in the last two decades. Of the 230 Tg aluminum entering China's anthroposphere, only 34% accumulates in in-use stock, and China's per-capita in-use stock (58 kg) in 2009 is 12% of the per-capita in-use stock in 2006 in the United States (490 kg). In addition, the share of secondary aluminum in the production of unwrought aluminum was less than 25% after 2000. These results imply that China's in-use stock of aluminum is still too “young” and small to generate high quantities of aluminum scrap for domestic secondary aluminum production. Because of this, China still depends mainly upon primary aluminum. From the 1980s to the period of 1990 to 2009, China changed from a net exporter of raw materials into a net importer and from a net importer of manufactured products into a net exporter. In 2009, China's static depletion time of bauxite was less than 15 years. Given the potential to increase its in-use stock, a secure supply of bauxite may become a challenge for China in the near future. Three dynamics driving China's rapid increase of primary aluminum production (PAP) were identified, and their impacts from 1991 to 2009 were quantified. The first, demand for aluminum by domestic in-use stock , was the most significant factor driving China's PAP increase. The second dynamic, China's net export of aluminum in the metallic form , became an important factor in stimulating PAP's increase in the 2000s. Lastly, the impact of losses to the environment in the metallic form on PAP is substantial and stays that way throughout time. Minimizing losses represents an opportunity to offset some demand.

Based on the characterization of aluminium life cycle in the anthroposphere, stocks and flows accounting of aluminium in mainland China for 2001, 2004 and 2007 was performed in this paper. Findings include the following: (1) the production and consumption of aluminium contained in aluminium-containing products generated from each life process grew from 2001 to 2004, and then to 2007; (2) the share of recycled aluminium in both production and consumption of unwrought aluminium was in the range of 20–26%, and a majority of aluminium scrap used to produce recycled aluminium for 2004 and 2007 came from net import, which revealed that China was still in the stage of mainly depending on primary aluminium rather than secondary aluminium and the in-use stock of aluminium was still too small to generate enough end-of-life (EOL) scrap; (3) China was a net importer of aluminium from the life cycle perspective, with total net import increasing from 2001 to 2004, and then to 2007; as for the trade structure, China was a net importer of raw materials including bauxite, alumina, EOL products and aluminium scrap, while a net exporter of unwrought aluminium and final products, and changed from a net importer of wrought products in 2001 and 2004 to a net exporter in 2007; (4) total quantity losses of aluminium in China increased from 2001 to 2004 and then to 2007 as a result of the growth of production; (5) depletion of domestic ore stock in China also increased from 2001 to 2004, and then to 2007, making China's depletion time of bauxite probably less than 15 years; (6) growth of in-use stock was 2.4 kg per capita, 3.7 kg per capita and 6.3 kg per capita for 2001, 2004 and 2007, respectively; (7) more than 80% of the addition of aluminium to the deposited stock came from aluminium losses in Bauxite Mining and Alumina Refining processes.