Understanding the spatial and temporal patterns of copper in-use stocks in China

Recycling potential of cobalt metal from end-of-life new energy passenger vehicles in China

The growing demand for new energy vehicles (NEVs) has resulted in a corresponding increase in demand for cobalt as a critical material. It is crucial to estimate the cobalt resource recycling potential of China's NEV industry to ensure a balance between the supply and demand for cobalt metal minerals. This article is based on using the historical data of the new energy passenger vehicle (NEPV) sales volume from 2013 to 2022 to estimate the NEPV sales volume from 2023 to 2035. On this basis, the Weibull distribution was used to analyse the different sales scenarios (low sales and high sales) of NEPVs in China, and the recycling potential of cobalt metal in NEPVs was evaluated under three battery life scenarios (8, 10 and 12 years) from 2023 to 2035. Based on the above scenarios, in 2035, the greatest recycling potential of cobalt is predicted to be 166.9 kilotonnes, with economic values of CNY 49.01-94.60 billion. Moreover, the extent to which the recycling potential of cobalt can cover the market demand for NEPVs was analysed. Our analysis concluded that recycling cobalt as a secondary supply has emerged as a necessary solution to supplement the primary supply, which can make a significant contribution to alleviating the pressure of the supply and demand.

Regulation Mechanism for Designing Decarbonization Pathways in the Copper Industry Toward Carbon Neutrality

The transformation of the global power structure caused by the carbon neutrality goal will promote copper consumption. It is crucial to explore the decarbonization pathways of the copper industry to help fulfill greenhouse gas (GHG) emission reduction targets. This study utilized material flow analysis and life cycle assessment methods to investigate 12 different subscenarios based on international trade, circular economy, technology evolution, and environmental market factors. Policy combination scenario is employed to reveal the mechanism of decarbonization. The results show that refined copper consumption in China is expected to increase by 62.3% in 2060 compared to 2020. The GHG emissions of China's copper industry will reach 9.1 million tonnes (Mt) CO2e in 2060, technology evolution and environmental market are crucial for realizing carbon neutrality goal of this industry, accounting for 26.4 and 47.2% of emissions reductions, respectively, between 2020 and 2060. International trade and circular economy play important roles in the high-quality carbon peaking stage; however, imported copper and domestic secondary copper will constitute the basic supply of copper resources in China in the long run, and the comparative advantages of them will gradually weaken. Policy combination scenario can achieve the incentive synergy effect, with GHG reduced to 0.5 Mt CO2e in 2060. The enhanced application of policies such as material substitution and carbon emission trading will further promote industry to achieve net-zero GHG emission. We suggest regulating the industry's structure based on the international systemic circulation pattern and accelerating the construction of a green circular chain in the short term to achieve sustainable copper supply and high-quality carbon peaking. Promoting a high-quality technology development strategy and enhancing the environmental markets are recommended in the long term to achieve carbon neutrality.

Gridded material stocks in China based on geographical and geometric configurations of the built-environment

Material stocks have created alternative perspectives in many environmental and climate studies. Their significance nonetheless may be under-explored, partially due to scarcity of more precise, timely and higher-resolution information. To address this limitation, our present study developed a gridded material stocks dataset for China in Year 2000 and 2020, by examining the geographical distribution and geometric configurations of the human-made stock-containing environment. The stocks of twelve materials embodied in five end-use sectors and 104 products and constructions were assessed at a resolution of 1 × 1 km grid. Material intensity in each product or construction component was carefully evaluated and tagged with its geometric conformation. The gridded stocks aggregately are consistent with the stock estimation across 337 prefectures and municipalities. The reliability of our assessment was also validated by previous studies from national, regional, to grid levels. This gridded mapping of material stocks may offer insights for urban-rural disparities, urban mining opportunity, and climate and natural disaster resilience.

Product, building, and infrastructure material stocks dataset for 337 Chinese cities between 1978 and 2020

Reliable city-level product, building, and infrastructure material stocks data are essential for understanding historical material use patterns, benchmarking material efficiency, and informing future recycling potentials. However, such urban material stocks data are often limited, due primarily to unavailable, inconsistent, or noncontinuous city-level statistics. Here, we provided such an Urban Product, Building, and Infrastructure Material Stocks (UPBIMS) dataset for China, a country that has undergone a remarkable urbanization process in the past decades, by collating different official statistics and applying various gap-filling methods. This dataset contains the stock of 24 materials contained in 10 types of products, buildings, and infrastructure in all 337 prefecture-level cities in China from 1978 to 2020. This quality controlled and unified dataset is the first of its kind with such a full coverage of all prefecture-level Chinese cities and can be used in a variety of applications, for example in urban geography, industrial ecology, circular economy, and climate change mitigation. Every piece of data is tagged with its source and the dataset will be periodically updated.

China material stocks and flows account for 1978-2018

As the world's top material consumer, China has created intense pressure on national or global demand for natural resources. Building an accurate material stocks and flows account of China is a prerequisite for promoting sustainable resource management. However, there is no annually, officially published material stocks and flows data in China. Existing material stocks and flows estimates conducted by scholars exhibit great discrepancies. In this study, we create the Provincial Material Stocks and Flows Database (PMSFD) for China and its 31 provinces. This dataset describes 13 materials' stocks, demand, and scrap supply in five end-use sectors in each province during 1978-2018. PMSFD is the first version of material stocks and flows inventories in China, and its uniform estimation structure and formatted inventories offer a comprehensive foundation for future accumulation, modification, and enhancement. PMSFD contributes insight into the material metabolism, which is an important database for sustainable development as well as circular economy policy-making in China. This dataset will be updated annually.

Estimation of waste outflows for multiple product types in China from 2010-2050

Material flow has been accelerated from underground natural minerals and is accumulating as aboveground waste stock. China is not only the largest producer and consumer of material-driven products, but also the largest generator of product waste. No official annual product waste data are released for China, which creates challenges especially in light of China's emerging waste management policies. Previous studies have presented only estimations of waste streams for single products. In this study, we considered three product types and 33 technological products and collected all the available data. A Kuznets curve and Bass diffusion model were employed to forecast their future consumption. Based on urban consumption metabolism, we created one systematic estimation model of product waste generation related to material flow and social regulation. Typical technological product waste outflows were estimated from 2010 to 2050, which can assist further material flow and environmental impact research, as well as waste management policy-making and technology development. The created model can be potentially extended to other types of product waste estimation.

Copper at the crossroads: Assessment of the interactions between low-carbon energy transition and supply limitations

This article aims to assess the impact of copper availability on the energy transition and to determine whether copper could become critical due to the high copper content of low-carbon technologies compared to conventional technologies. In assessing copper availability through to 2050, we rely on our linear programming world energy-transport model, TIAM-IFPEN. We examine two climate scenarios (2 °C and 4 °C) with two mobility shape, implemented with a recycling chain. The penetration of low-carbon technologies in the transport and energy sectors (electric vehicles and low-carbon power generation technologies) is likely to significantly increase copper demand by 2050. To investigate how tension over copper resources can be reduced in the energy transition context, we consider two public policy drivers: sustainable mobility and recycling practices. Results show that in the most stringent scenario, the cumulative primary copper demand between 2010 and 2050 is found to be 89.4% of the copper resources known in 2010. They also pinpoint the importance of China and Chile in the future evolution of the copper market.

Economic and environmental feasibility of hydrometallurgical process for recycling waste mobile phones

Waste mobile phones contain significant amounts of valuable metals and non-metallic materials. Consequently, the extraction of valuable materials from discarded phones, which is a more cost-effective method compared with primary mining, is an essential step for maximizing the recovery of secondary resources and minimizing e-waste pollution. We designed a green and efficient path for recovering valuable metals from waste mobile phones and explored its technical feasibility from both environmental and economic perspectives through life cycle assessment and revenue expenditure model. The results showed that the hydrometallurgical process had three characteristics of high recovery efficiency, significant environmental friendliness and economic feasibility. The recovery efficiencies of valuable metals were higher than 90%. Simultaneously, the return on investment was 29%, indicating that the recycling enterprises can achieve self-sufficiency. Thirdly, the environmental benefits were more significant compared to environmental damage released by hydrometallurgical process, representing a significant environmental friendliness. Within the overall recycling process, the core process made the greatest contribution to the environmental burden (45.38-65.68%), followed by manual disassembly process. A comparison of sub-processes in core process revealed that the mechanical crushing and sorting phase had the greatest environmental impacts that were primarily attributed to power consumption. Consequently, future research should focus on the development of energy-efficient pretreatment techniques and energy-saving equipment. The industrial practice of recycling waste mobile phones is still in its infancy in China. Future studies should also focus on the comparing different treatment processes, with the aim of providing technical support for the advancement of industry.

Examining the Temporal Demand and Sustainability of Copper in China

A comprehensive study is carried out to determine (1) the annual historical demand and supply, (2) the annual prospective demand, and (3) the carrying capacity and future sustainability of copper resources in China. The results of the first analysis show that both the demand and the supply have substantially increased since 2000 after remaining relatively minute for the period from 1950 to 2000. By 2015, the per capita total and domestic demands had reached 7.6 and 5.4 kg, respectively. The annual demand prospects suggest that the copper demand will peak in 2030 and either stabilize or marginally drop thereafter. This was found to be the case for all population variants and demand growth rates that were considered herein, with the exception of the "stable scenario". Under the considered scenarios, the domestic demand in the year 2050 is predicted to fall by 6.7-15 million metric tons (Mt), while the total demand will likely fall by 9.4-21.2 Mt. The projected drastic increase in the cumulative primary demand suggests that China should pursue more industrially sustainable options. If the current trends continue, demand will likely surpass even the projected reserve base of 2050 sometime from 2025 to 2035 unless necessary actions to change the course are initiated as soon as possible. Chinese efforts to promote recycling in recent decades have been admirable but are not sufficient to meet the primary demand, thus leaving a large proportion of the demand to be met using imports. Thus, to reduce the primary copper imports, it is desirable to increase recycling rates to 60-70%. The shortcomings of the domestic recycling industry include poor end-of-life collection and an elastic policy framework. These issues merit attention in the short term to increase the long-term sustainability of copper resources in China.

Taking Stock of Built Environment Stock Studies: Progress and Prospects

Built environment stocks (buildings and infrastructures) play multiple roles in our socio-economic metabolism: they serve as the backbone of modern societies and human well-being, drive the material cycles throughout the economy, entail temporal and spatial lock-ins on energy use and emissions, and represent an extensive reservoir of secondary materials. This review aims at providing a comprehensive and critical review of the state of the art, progress, and prospects of built environment stocks research which has boomed in the past decades. We included 249 publications published from 1985 to 2018, conducted a bibliometric analysis, and assessed the studies by key characteristics including typology of stocks (status of stock and end-use category), type of measurement (object and unit), spatial boundary and level of resolution, and temporal scope. We also highlighted the strengths and weaknesses of different estimation approaches. A comparability analysis of existing studies shows a clearly higher level of stocks per capita and per area in developed countries and cities, confirming the role of urbanization and industrialization in built environment stock growth. However, more spatially refined case studies (e.g., on developing cities and nonresidential buildings) and standardization and improvement of methodology (e.g., with geographic information system and architectural knowledge) and data (e.g., on material intensity and lifetime) would be urgently needed to reveal more robust conclusions on the patterns, drivers, and implications of built environment stocks. Such advanced knowledge on built environment stocks could foster societal and policy agendas such as urban sustainability, circular economy, climate change, and United Nations 2030 Sustainable Development Goals.

Product and Metal Stocks Accumulation of China's Megacities: Patterns, Drivers, and Implications

The rapid urbanization in China since the 1970s has led to an exponential growth of metal stocks (MS) in use in cities. A retrospect on the quantity, quality, and patterns of these MS is a prerequisite for projecting future metal demand, identifying urban mining potentials of metals, and informing sustainable urbanization strategies. Here, we deployed a bottom-up stock accounting method to estimate stocks of iron, copper, and aluminum embodied in 51 categories of products and infrastructure across 10 Chinese megacities from 1980 to 2016. We found that the MS in Chinese megacities had reached a level of 2.6-6.3 t/cap (on average 3.7 t/cap for iron, 58 kg/cap for copper, and 151 kg/cap for aluminum) in 2016, which still remained behind the level of western cities or potential saturation level on the country level (e.g., approximately 13 t/cap for iron). Economic development was identified as the most powerful driver for MS growth based on an IPAT decomposition analysis, indicating further increase in MS as China's urbanization and economic growth continues in the next decades. The latecomer cities should therefore explore a wide range of strategies, from urban planning to economy structure to regulations, for a transition toward more "metal-efficient" urbanization pathways.

Nighttime Light Images Reveal Spatial-Temporal Dynamics of Global Anthropogenic Resources Accumulation above Ground

Urbanization and industrialization represent largely a process of transforming materials from biosphere and lithosphere to anthroposphere. Understanding the patterns of such anthropogenic material stock accumulation is thus a fundamental prerequisite to assess and sustain how humans alter the biophysical movements of resources around Earth. Previous studies on these anthropogenic stocks, however, are often limited to the global and national scales, due to data gaps at higher spatial resolutions. Here, based on a new set of national materials stock data and nighttime light images, we developed a regression model to map the global anthropogenic stocks of three fundamental construction materials (steel, concrete, and aluminum) at a 1 × 1 km level from 1992 to 2008. We revealed an unevenly distributed pattern, with over 40% found in three belts: from England across the Channel to Western Europe; from eastern coast China to South Korea and Japan; and from Great Lakes along eastern coast of United States to Florida. The spatial-temporal dynamics of global anthropogenic stocks at smaller spatial scales reflect a combined effect of physical geography, architectural and construction specifications, and socioeconomic development. Our results provide useful data that can potentially support policy-makers and industry on resource efficiency, waste management, urban mining, spatial planning, and environmental sustainability at regional and urban scales.

Characterizing copper flows in international trade of China, 1975-2015

Since the economic reform, China has actively participated in the global market with rapid industrialization and gradually dominated the utilization and consumption of some critical materials, one of which is copper. China has reigned the global anthropogenic cycle of copper since 2004. We explore copper flows along with the international trade of China during 1975-2015, through life cycle lens, from ore to final products. Our main finding is that China has become more active in the copper-related trade, indicated by its great increase in trade volume and the number of trade partners. The physical volume of copper flows through trade increased over 119 times between 1975 and 2015, mainly because of more imported raw materials of copper and exported copper products. Generally, China is a net importer of copper, with increasing import dependence through the study period, whereas the degree of dependence slightly decreased from 2010 to 2015. The indicator of Export Support Rate took a decreasing percentage, which has fallen about 35% since 2010. It suggests China's changing position in the global resource and manufacturing market. In terms of trade price of different copper products, the price of imported copper concentrate was noticeably higher than that of exported one, revealing the poor copper resource endowment of China; while the different trend of copper semis in recent years signifies that China is in urgent need to improve its capability of producing high value-added semis. From international trade perspective, the copper resource of China presented stable supply as well as demand. The One Belt One Road strategy proposed by the state will further expand both the resource and market of copper.

Elaborating the History of Our Cementing Societies: An in-Use Stock Perspective

Modern cities and societies are built fundamentally based on cement and concrete. The global cement production has risen sharply in the past decades due largely to urbanization and construction. Here we deployed a top-down dynamic material flow analysis (MFA) model to quantify the historical development of cement in-use stocks in residential, nonresidential, and civil engineering sectors of all world countries. We found that global cement production spreads unevenly among 184 countries, with China dominating the global production and consumption after the 1990s. Nearly all countries have shown an increasing trend of per capita cement in-use stock in the past century. The present per capita cement in-use stocks vary from 10 to 40 tonnes in major industrialized and transiting countries and are below 10 tonnes in developing countries. Evolutionary modes identified from historical patterns suggest that per capita in-use cement stock growth generally complies with an S-shape curve and relates closely to affluence and urbanization of a country, but more in-depth and bottom-up investigations are needed to better understand socioeconomic drivers behind stock growth. These identified in-use stock patterns can help us better estimate future demand of cement, explore strategies for emissions reduction in the cement industry, and inform CO₂ uptake potentials of cement based products and infrastructure in service.

High copper concentrations produce genotoxicity and cytotoxicity in bovine cumulus cells

The aim of this study was to investigate the cytotoxic and genotoxic effects of high copper (Cu) concentrations on bovine cumulus cells (CCs) cultured in vitro. We evaluated the effect of 0, 120, 240, and 360 μg/dL Cu added to in vitro maturation (IVM) medium on CC viability assessed by the trypan blue (TB)-fluorescein diacetate (FDA) and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, apoptosis, and DNA damage. Differences in cell viability assessed by TB-FDA were not significant among CC treated with 0, 120, 240, and 360 μg/dL Cu. However, mitochondrial activity assessed by MTT was lower in CC cultured with 120, 240, and 360 μg/dL Cu as compared with the control (p < 0.01). Percentages of apoptotic cells were higher when CCs were treated with 120, 240, and 360 μg/dL Cu (p < 0.05) due to higher frequencies of late apoptotic cells (p < 0.05). The frequency of live cells diminished in a dose-dependent manner when Cu was added to the culture medium. Whereas genetic damage index (GDI) increased significantly in CC cultured in the presence of 240 and 360 μg/dL Cu (p ˂ 0.05), DNA damage increased at all Cu concentrations tested (p ˂ 0.05). These results indicate that Cu induces cytotoxic and genotoxic effects in bovine CC.

Uncovering the Recycling Potential of "New" WEEE in China

Newly defined categories of WEEE have increased the types of China's regulated WEEE from 5 to 14. Identification of the amounts and valuable-resource components of the "new" WEEE generated is critical to solving the e-waste problem, for both governmental policy decisions and recycling enterprise expansions. This study first estimates and predicts China's new WEEE generation for the period of 2010-2030 using material flow analysis and the lifespan model of the Weibull distribution, then determines the amounts of valuable resources (e.g., base materials, precious metals, and rare-earth minerals) encased annually in WEEE, and their dynamic transfer from in-use stock to waste. Main findings include the following: (i) China will generate 15.5 and 28.4 million tons WEEE in 2020 and 2030, respectively, and has already overtaken the U.S. to become the world's leading producer of e-waste; (ii) among all the types of WEEE, air conditioners, desktop personal computers, refrigerators, and washing machines contribute over 70% of total WEEE by weight. The two categories of EEE-electronic devices and electrical appliances-each contribute about half of total WEEE by weight; (iii) more and more valuable resources have been transferred from in-use products to WEEE, significantly enhancing the recycling potential of WEEE from an economic perspective; and (iv) WEEE recycling potential has been evolving from ∼16 (10-22) billion US$ in 2010, to an anticipated ∼42 (26-58) billion US$ in 2020 and ∼73.4 (44.5-103.4) billion US$ by 2030. All the obtained results can improve the knowledge base for closing the loop of WEEE recycling, and contribute to governmental policy making and the recycling industry's business development.