Transforming the Cement Industry into a Key Environmental Infrastructure for Urban Ecosystem: A Case Study of an Industrial City in China

Under the dual pressure of environmental constraints and increasingly thin profit margins, the cement industry in China is in a predicament. To alleviate the environmental and the economic pressure of the cement industry and to tackle the problem of delayed environmental infrastructure construction, this article introduced an urban ecosystem in which the cement industry was transformed into an effective complement to environmental infrastructure. The Xinfeng Cement Industrial Park in China, which has a production capacity of 5 million tonnes per annum (Mt/a) of clinker, was chosen as a case study. Our methodology involved proposing technologies to develop an efficient cement plant‐centered urban ecosystem; evaluating its environmental and economic performance; identifying barriers in its promotion; and proposing supportive policies. Results showed that the city's waste recycling ratio rose from about 50% to 70%, saving 0.6 Mt/a of coal equivalent and reducing about 3.0 Mt/a of resulting carbon dioxide (CO₂) emissions. The life span of the city's landfill site was extended by about 30 years. The total investment was 3.2 billion yuan (about US$480 million), 1 with an average payback period of 3 years. The Xinfeng Cement Industrial Park was transformed from an energy‐intensive consumer and a significant CO₂ emitter to a key industrial waste recycler, a crucial municipal waste co‐processor, an important new building material supplier, and a potential energy producer. Last, the “not‐in‐my‐back‐yard” (NIMBY) effect from constructing new environmental infrastructure was also avoided.     

A Carbon Footprint of High‐Speed Railways in China: A Case Study of the Beijing‐Shanghai Line

A carbon footprint (CF) assessment of Chinese high‐speed railways (HSRs) can help guide further development of the world's longest HSR network. In this research, a hybrid economic input‐output and life cycle assessment (EIO‐LCA) method was applied to estimate the CF of the Beijing‐Shanghai HSR line. Specific CFs were analyzed of different subsystems of the line, different stages of production, and three calculation scopes. Results showed that the annual CF of the Beijing‐Shanghai HSR is increasing, whereas the per‐passenger CF constantly declined between 2011 and 2014. Scope 1 emissions account for an average of 4% of the total annual CF, Scope 2 contribute 71%, and Scope 3 comprise 25%. Among the different stages, operation contributes the largest (71%), followed by construction (20%) and maintenance (9%). In the construction stage, the bridges have the largest CF, followed by trains, and then rails. A trade‐off exists between the increase in carbon emissions due to construction of bridges and the reduction in operation emissions affected by leveling changes in terrain. The Beijing‐Shanghai HSR line has a relatively higher per‐passenger CF than eight other HSR lines, which is largely due to China's coal‐based carbon‐intensive energy mix of electricity generation, high proportion of bridges, higher operating speed, and heavier train body. In the future, cleaner electricity supply options, more efficient raw material production, and improvement of trains are keys to reducing the CF of Chinese HSRs.     

Materials Metabolism Analysis of China's Highway Traffic System (HTS) for Promoting Circular Economy

With the rapid growth of highway mileage and vehicles, the Chinese highway traffic system (HTS) has become one of the great resource consumers. This article attempts to evaluate the material metabolism of China's HTS during 2001–2005 using the approach of material flow analysis (MFA) and to explore possible measures to promote circular economy throughout HTS. We measured a set of indicators to illustrate the whole material metabolism of China's HTS. The results indicated that the direct material input (DMI) of China's HTS increased from 1181.26 million tonnes (Mt) in 2001 to 1,874.57 Mt in 2005, and about 80% of DMI was accumulated in the system as infrastructure and vehicles. The domestic processed output (DPO) increased by 59.0% from 2001 to 2005. Carbon dioxide and solid waste accounted for 80.5% and 10.4% of DPO, respectively. The increase of resource consumption and pollutant emissions kept pace with the growth of transportation turnover. All these suggest that China's HTS still followed an extensive linear developing pattern with large resource consumption and heavy pollution emissions during the study period, which brought great challenges to the resources and the environment. Therefore, it's high time for China to implement a circular economy throughout the HTS by instituting resource and energy savings, by reducing emissions in the field of infrastructure construction and maintenance, by reducing vehicles’ energy and materials consumption, and by recycling waste materials.     

Uncovering urban transportation infrastructure expansion and sustainability challenge in Bangkok: Insights from a material stock perspective

Development of transportation infrastructure that extends roads and railways in Bangkok has overlooked the negative environmental impact of construction material accumulation. To analyze the extent of this impact, we originally established road and railway's material intensity coefficients and investigated spatially explicit roadway and railway material stock (MS) for the years of 2004, 2009, 2014, 2019, and 2037, based upon the master plans’ target year. We further analyzed how MS evolution relates to the city's socio-economic indicators and CO₂ emission. Significant growth is found in transportation MS during 2004–2019, and roadways particularly increased from 122 to 164 million metric tons (Mt). The master plans would require 43 and 6.55 Mt construction materials for roadway and railway extension, respectively, by 2037. More material-intensive roads (cross-provincial highways and major local roads) built to the suburbs of the cities and underground/elevated structures of the mass rapid transit system in dense urban areas will require three times the annual cement and steel consumption of that in the 2004–2019 period. Furthermore, a 2–3 fold increase in the number of registered vehicles and associated CO₂ emissions during the study period have brought questions to the transportation infrastructure MS efficiency. The findings of this study will enable informed decision-making regarding the concern of resource consumption and for considering environmentally friendly approaches in urban transportation planning for Bangkok and other developing cities.     

Decoupling Analysis of the Environmental Mountain—with Case Studies from China

The resource‐development trajectory of developed countries after the Industrial Revolution of the eighteenth and nineteenth centuries can be portrayed as an “environmental mountain” (EM). It is important for developing countries to decouple their resource use from economic growth and tunnel through the EM. In this study, we embedded the decoupling indicators for resource use and waste emissions into EM curves to quantify China's progress in tunneling through the EM over a specific time period. Five case studies regarding the conditions required for decoupling energy consumption, crude steel production, cement production, CO₂ emissions, and SO₂ emissions from economic growth in China were conducted. The results indicated that during 1985–2010 the trajectories of energy consumption, and CO₂ and SO₂ emissions in China met the requirements for tunneling through the EM, but the trajectories of cement and steel production did not. Based on these results, suggestions regarding China's environmental policies are provided to enable the country to tunnel through the EM.     

Peak cement‐related CO2 emissions and the changes in drivers in China

In order to fight against the climate change, China has set a series of emission reduction policies for super‐emitting sectors. The cement industry is the major source of process‐related emissions, and more attention should be paid to this industry. This study calculates the process‐related, direct fossil fuel–related, and indirect electricity‐related emissions from China's cement industry. The study finds that China's cement‐related emissions peaked in 2014. The emissions are, for the first time, divided into seven parts based on the cement used in different new building types. The provincial emission analysis finds that developed provinces outsourced their cement capacities to less developed regions. This study then employs index decomposition analysis to explore the drivers of changes in China's cement‐related emissions. The results show that economic growth was the primary driver of emission growth, while emission intensity and efficiency were two offsetting factors. The changes in the construction industry's structure and improvement in efficiency were the two major drivers that contributed to the decreased emissions since 2014.     

Dynamic Modeling of In‐Use Cement Stocks in the United States

A dynamic substance‐flow model is developed to characterize the stocks and flows of cement utilized during the 20th century in the United States, using the generic cement life cycle as a systems boundary. The motivation for estimating historical inventories of cement stocks and flows is to provide accurate estimates of contemporary cement in‐use stocks in U.S. infrastructure and future discards to relevant stakeholders in U.S. infrastructure, such as the federal and state highway administrators, departments of transportation, public and private utilities, and the construction and cement industries. Such information will assist in planning future rehabilitation projects and better life cycle management of infrastructure systems. In the present policy environment of climate negotiations, estimates of in‐use cement infrastructure can provide insights about to what extent built environment can act as a carbon sink over its lifetime. The rate of addition of new stock, its composition, and the repair of existing stock are key determinants of infrastructure sustainability. Based upon a probability of failure approach, a dynamic stock and flow model was developed utilizing three statistical lifetime distributions—Weibull, gamma, and lognormal—for each cement end‐use. The model‐derived estimate of the “in‐use” cement stocks in the United States is in the range of 4.2 to 4.4 billion metric tons (gigatonnes, Gt). This indicates that 82% to 87% of cement utilized during the last century is still in use. On a per capita basis, this is equivalent to 14.3 to 15.0 tonnes of in‐use cement stock per person. The in‐use cement stock per capita has doubled over the last 50 years, although the rate of growth has slowed.     

Forest fragmentation in China and its effect on biodiversity

Land‐use change is fragmenting natural ecosystems, with major consequences for biodiversity. This paper reviews fragmentation trends – historical and current – in China, the fourth largest country on Earth, and explores its consequences. Remote sensing makes it possible to track land‐use change at a global scale and monitor fragmentation of dwindling natural landscapes. Yet few studies have linked fragmentation mapped remotely with impacts on biodiversity within human‐modified landscapes. Recent reforestation programs have caused substantial increases in forest cover but have not stopped fragmentation, because the new forests are mostly monocultures that further fragment China's remnant old‐growth lowland forests that harbour the highest levels of biodiversity. Fragmentation – and associated biodiversity declines – is unevenly distributed in China's forests, being most problematic where agricultural expansion is occurring in the southwest and northeast, serious in the densely populated eastern regions where urbanisation and transport infrastructure are modifying landscapes, but less of a problem in other regions. Analyses of temporal trends show that the drivers of forest fragmentation are shifting from mainly agricultural expansion to urbanisation and infrastructure development. Most of China's old‐growth forests persist in small, isolated fragments from which many native species have disappeared, on land unsuitable for human utilisation. Fragmentation throughout China is likely to have major consequences on biodiversity conservation, but few studies have considered these large‐scale processes at the national level. Our review fills this research gap and puts forward a systematic perspective relevant to China and beyond.     

以材料“创造”土地？——中国城市化进程的一个重要特征

中国快速城市化进程的一个重要特征是以土地为载体,通过大量投入钢铁、水泥等建材大规模修建城市建筑和基础设施,创造出大量的城市生产和生活空间。利用1985—2010年中国省级行政单元城市建成区总面积、城市居住用地总面积、城市住宅总面积和城市住宅建筑材料总使用量等数据,识别城市扩张模式,揭示中国城市化进程中土地、建筑面积及其构筑材料三者间的关系。研究表明2000年是中国城市扩张的重要分界点,2000年之前中国各省份的城市建成区总面积、城市住宅总面积和城市住宅建筑材料总使用量均较小且省份间差异不大,2000年之后三者迅速增长且省份间差异逐渐扩大。在地区尺度上,三者均呈现东部地区最高、中部次之、西部最低的特点,地区内部差异则表现为东部地区最大、西部次之、中部最小的特征。大多数省份的城市住宅总面积及其构筑材料总量随着城市建成区的扩张而增长,表明城市在发展初期以扩大建成区和水平扩张为主。随着城市化水平的不断提高,城市内部空间重组和用地置换导致高层建筑逐步替代了原有的单层或低矮建筑,城市扩张的方向由依赖土地的水平扩张转向以大量使用建筑材料为基础的垂直扩张,使得许多省份的城市住宅总面积逐渐超过辖区内居住用地总面积。这种以建筑材料"创造"出更多"土地"的城市垂直扩张在满足人们对城市生产和生活空间需求的同时,有利于节约土地资源和保护生态空间,但需要以消耗更多的建筑材料并承担建筑材料在开采、制造、运输、使用和废弃过程中所造成的环境影响为代价。     

A life cycle model for high-speed rail infrastructure: environmental inventories and assessment of the Tours-Bordeaux railway in France

Purpose

The objective of the study is to progress towards a comprehensive component-based Life Cycle Assessment model with clear and reusable Life Cycle Inventories (LCIs) for high-speed rail (HSR) infrastructure components, and to assess the main environmental impacts of HSR infrastructure over its lifespan, to finally determine environmental hotpots and good practices.

Methods

A process-based LCA compliant with ISO 14040 and 14044 is performed. Construction-stage LCIs rely on data collection conducted with the concessionaire of the HSR line combined with EcoInvent 3.1 inventories. Use and End-of-Life stages LCIs rest on expert feedback scenarios and field data. A set of 13 midpoint indicators is proposed to capture the diversity of the environmental damage: climate change, consumptions of primary energy and non-renewable resources, human toxicity and ecotoxicities, eutrophication, acidification, radioactive and bulk wastes, stratospheric ozone depletion, and summer smog. Three characterization methods are used: the “Cumulative Energy Demand” method to quantify energy demand, the EDIP method for waste productions, and the CML method for the rest.

Results and discussion

The study shows major contributions to environmental impact from rails (10–71%), roadbed (3–48%), and civil engineering structures (4–28%). More limited impact is noted from ballast (1–22%), building machines (0–17%), sleepers (4–11%), and power supply system (2–12%). The two last components, chairs and fasteners, have negligible impact (max. 1 and 3% of total contributions, respectively). Direct transportation can contribute up to 18% of total impact. The production and maintenance stages contribute roughly equally to environmental deterioration (respectively average of 62 and 59%). Because the End-of-Life (EoL) mainly includes recycling with environmental credit accounted for in our 100:100 approach, this stage has globally a positive impact (??9 to ??98%) on all the impact categories except terrestrial ecotoxicity (58%), radioactive waste (11%), and ozone depletion (8%). Contribution analyses show that if concrete production is one of the important contributing processes over the construction stage, primary steel production is unquestionably the most important process on all the impact categories over the entire life cycle.

Conclusions

These results are of interest for public authorities and the rail industry, in order to consider the full life cycle impacts of transportation infrastructure in a decision-making process with better understanding and inclusion of the environmental constraints. Suggestions are provided in this way for life cycle good practices—for instance as regards gravel recycling choices—and additional research to reduce the impact of current major contributors.

     

Application of a Life Cycle Model for European Union Policy‐Driven Waste Management Decision Making in Emerging Economies

Solid waste life cycle modeling has predominantly focused on developed countries, but there are significant opportunities to assist developing and transition economies to minimize the environmental impact of solid waste management (SWM). Serbia is representative of a transition country and most (92%) of its waste is landfilled. As a Candidate European Union (EU) country, Serbia is expected to implement SWM strategies that meet EU directives. The Solid Waste Life‐Cycle Optimization Framework (SWOLF) was used to evaluate scenarios that meet EU goals by 2030. Scenarios included combinations of landfills, anaerobic digestion, composting, material recovery facilities (MRFs), waste‐to‐energy (WTE) combustion, and the use of refuse‐derived fuel in cement kilns. Each scenario was evaluated with and without separate collection of recyclables. Modeled impacts included cost, climate change, cumulative fossil energy demand, acidification, eutrophication, photochemical oxidation, total eco‐toxicity, and total human toxicity. Trade‐offs among the scenarios were evaluated because no scenario performed best in every category. In general, SWM strategies that incorporated processes that recover energy and recyclable materials performed well across categories, whereas scenarios that did not include energy recovery performed poorly. Emissions offsets attributable to energy recovery and reduced energy requirements associated with remanufacturing of recovered recyclables had the strongest influence on the results. The scenarios rankings were robust under parametric sensitivity analysis, except when the marginal electricity fuel source changed from coal to natural gas. Model results showed that the use of existing infrastructure, energy recovery, and efficient recovery of recyclables from mixed waste can reduce environmental emissions at relatively low cost.     

The Characteristics and Trends of Socioeconomic Metabolism in China

China has become the country with the largest resource use and has high levels of waste emissions that pose a great management challenge. To provide more details about environmental problems and to find effective solutions, this article analyzed the scale, structure, and trend of the socioeconomic metabolism in China during the period 1992–2014 based on economy‐wide material flow accounts (EW‐MFA), and predicted resource use during the period of the 13th Five‐Year Plan. The results of this study show that the scale of China's socioeconomic metabolism in China increased more than twofold, during 1992–2014. However, after 2011, with the economic slowdown, the growth rates of total material requirement (TMR), direct material input (DMI), and domestic processed output (DPO) began to decrease. China may reach an inflection point, but this point will probably not be approached before the year 2020. Material recycling (MR) has played an important role in improving resource productivity, improving it by 92.52 renminbi per tonne in 2014. Metallic minerals and fossil fuels are the main sources of hidden flow. Carbon dioxide (CO₂) emissions, construction waste, and agricultural emissions have become the major sources of DPO. Because of the 13th Five‐Year Plan, China may slow the growth rate of DMI and may save 10.26 gigatonnes of resources during 2015–2020. Resource productivity is predicted to increase by 15.91%. Imports and MR may play more important roles. These suggestions are made: (1) strengthening the recycling system; (2) stronger policies, especially in metallic mineral and fossil fuels; (3) developing management systems for CO₂ emissions, construction waste, and agricultural emissions; and (4) adjusting China's economic structure.     

Greening China's Wastewater Treatment Infrastructure in the Face of Rapid Development: Analysis Based on Material Stock and Flow through 2050

Wastewater treatment infrastructure (WWTI) construction in China has entered an accelerated stage of development in recent years as a result of rapid economic growth, urbanization, and the demand for improving water quality. As a result, a large amount of resources and materials will be allocated for the WWTI, and it is particularly important to find ways to reduce resource consumption effectively so that social dematerialization and sustainable development can be achieved. In this study, we employed the dynamic material flow model to estimate the material flows and stocks of WWTIs and the associated carbon dioxide (CO₂) emissions through 2050, considering effects of a rise in water consumption, a longer lifetime, and an increased material recycling rate. Our results indicate that material consumption in WWTIs will increase rapidly through 2025 to meet the needs of the increased volume of discharged wastewater as well as to overcome the shortage of existing wastewater treatment plants. In contrast with the moderate effects of rise in water consumption, prolonging the lifetime will greatly reduce material consumption in WWTI construction during the period 2030–2050, and approximately 60% of the total material input will be saved in the medium‐lifetime scenario, compared with the short‐lifetime scenario. Material output and CO₂ emissions associated with WWTIs will be reduced by 87% and 37%, respectively, in the medium‐lifetime scenario, compared with the short‐lifetime scenario, under high‐water‐consumption growth. Our results highlight the great importance of pipeline construction and cement consumption in resource consumption associated with WWTI construction in China. Moreover, this study also examined the potential ways to reduce material consumption in WWTI construction in the context of the demand chain, the design, construction, operation and management, and demolition.     

Global Patterns and Trends for Non‐Metallic Minerals used for Construction

Despite accounting for almost 50% of global material use, nonmetallic minerals—mostly used for construction of buildings and infrastructure—are the material flow analysis (MFA) category with the highest uncertainty. The main reason for this is incomplete reporting in official national statistics because of ease of availability and the low per‐unit cost of these materials. However, the environmental burden associated with nonmetallic minerals, which include energy use for extraction and transport, land‐use change, and disposal of large amounts of construction demolition waste, call for a thorough understanding of the magnitude of nonmetallic mineral flows. Previous estimates for nonmetallic minerals have used simplistic assumptions. This study aims to increase the precision of nonmetallic mineral accounts at national and global level using consumption of bitumen, bricks, cement, and railways in combination with technical coefficients from the engineering literature to infer the actual yearly consumption of nonmetallic minerals. We estimate the extraction of nonmetallic minerals and provide uncertainty estimates for the new accounts as well as information about consumption by different sectors. Analyzing the evolution of consumption for seven world regions, we find that, in North America and Europe, the consumption of nonmetallic minerals over the past 40 years has followed the growth patterns of population, whereas for all other regions consumption has been closely related to gross domestic product (GDP). A more accurate account of global and country‐by‐country extraction of nonmetallic minerals may provide insights into supply shortages and inform waste management strategies for construction and demolition waste.     

Ecology profile of the german high-speed rail passenger transport system,ICE

Intention, Goal, Scope, Background, Objectives  Environmental effects caused by the railway transport services have rarely been investigated in depth from a systemic point of view. A screening LCA, called ecology profile, of the German high-speed passenger train system, the ICE, is presented here, based on a study conducted by the University of Halle and the Deutsche Bahn AG, the major German rail operator. In this study, the resource consumption caused by traction, manufacturing and maintenance of ICE trains, as well as construction and operation of the supporting rail infrastructure and buildings, have been evaluated using cumulative energy demand (CED), cumulative material input per service unit (MIPS) and CO₂ emissions as indicators. Methods  Approximately 200 items of inventory data were collected from DB AG experts, manufacturers, site balances and the associated literature. They were allocated in order to derive 100-person-kilometre-related mass and energy consumption figures. The appropriate CED, MIPS and CO₂ factors were applied in order to quantify the indirect efforts associated with the inventory data. Conclusions  For the reference high-speed route investigated, Hanover-Wuerzburg, the railroad infrastructure does not contribute the high share of resource consumption to the life cycle of the transport service which was expected from other studies. For the reference route, the CED of the infrastructure contributes 13% to the total CED per 100 person kilometres, whilst the energy demand of the traction process dominates the life cycle. Within the railway infrastructure, the construction of tunnels and the heating of rail points during winter time are significant primary-energy active components, whereas the energy requirement for maintaining the railway stations is a minor factor in comparison. The environmental impact of new technologies for designing rail tracks have also been analysed. The new ballastless slab track technology investigated needs higher absolute resource inputs in the construction phase compared with the traditional gravel bed, but due to higher life expectancy, it competes favourably at the 100-person-kilometre level, at least in terms of material requirements. Efforts to reduce the traction energy consumption of the ICE train will have the greatest impact on the CED of the transport system. In summary, a total of 48 kg of solid primary resources are needed for a passenger to travel 100 km by ICE. Recommendations/Outlook  The results presented can be used for modelling other high-speed railway transport systems. A comparison of the ecology profiles of the German, French and Japanese high-speed train systems would be of interest in order to identify potential areas for improvement. Additional studies are needed to evaluate the short-hop, commuter train service. Further efforts should be directed to comparing the infrastructure of the high speed train and that of highway road traffic.     

The Greenhouse Gas Footprint of China's Food System: An Analysis of Recent Trends and Future Scenarios

Food chain systems (FCSs), which begin in agricultural production and end in consumption and waste disposal, play a significant role in China's rising greenhouse gas (GHG) emissions. This article uses scenario analysis to show China's potential trajectories to a low‐carbon FCS. Between 1996 and 2010, the GHG footprint of China's FCSs increased from 1,308 to 1,618 megatonnes of carbon dioxide equivalent (Mt CO₂‐eq), although the emissions intensity of all food categories, except for aquatic food, recorded steep declines. We project three scenarios to 2050 based on historical trends and plausible shifts in policies and environmental conditions: reference scenario; technology improvement scenario; and low GHG emissions scenario. The reference scenario is based on existing trends and exhibits a large growth in GHG emissions, increasing from 1,585 Mt CO₂‐eq in 2010 to 2,505 Mt CO₂‐eq in 2050. In the technology improvement scenario, emissions growth is driven by rising food demand, but that growth will be counterbalanced by gains in agricultural technology, causing GHG emissions to fall to 1,413 Mt CO₂‐eq by 2050. Combining technology improvement with the shift to healthier dietary patterns, GHG emissions in the low GHG emissions scenario will decline to 946 Mt CO₂‐eq in 2050, a drop of 41.5% compared with the level in 2010. We argue that these are realistic projections and are indeed indicative of China's overall strategy for low‐carbon development. Improving agricultural technology and shifting to a more balanced diet could significantly reduce the GHG footprint of China's FCSs. Furthermore, the transition to a low‐carbon FCS has potential cobenefits for land sustainability and public health.     

First geolocator tracks of Swedish red‐necked phalaropes reveal the Scandinavia‐Arabian Sea connection

We studied migration and wintering patterns of a wader with a pelagic lifestyle during the non‐breeding period, the red‐necked phalarope Phalaropus lobatus. Using light‐level geolocation, we obtained three full annual tracks and one autumn migration track of male red‐necked phalaropes caught during breeding in Scandinavia. These tracks confirmed expectations that individuals from the Scandinavian population winter in the Arabian Sea. Migration was accomplished in two to four migration leaps, staging for a few days in the Gulf of Finland (autumn) or the southern Baltic Sea (spring) and for up to a month in or near the Black and Caspian Sea (autumn and spring). In addition, travel speeds suggested that only the flights between the Baltic and Black/Caspian Sea are non‐stop, and thus the birds seem to make additional short stops during the other flights. Stopover time in the Black/Caspian Sea is only 8–10 d in spring but up to 36 d in autumn, which is longer than expected if only used for pre‐migratory fattening to cover the ca 2000 km to the Gulf of Oman. After entering the Arabian Sea via the Gulf of Oman, birds dispersed over the entire presumed winter range. Winter movements appear to correspond to the spatio‐temporal patterns in primary production linked to seasonally changing monsoon winds. These are not only the first tracks of Scandinavian red‐necked phalaropes, but also the first seabird tracks in the Arabian Sea, one of the most productive and dynamic marine areas on the planet.     

Geospatial Characterization of Material Stock in the Residential Sector of a Latin‐American City

Building stock constitutes a huge repository of construction materials in a city and a potential source for replacing primary resources in the future. This article describes the application of a methodological approach for analyzing the material stock (MS) in buildings and its spatial distribution at a city‐wide scale. A young Latin‐American city, the city of Chiclayo in Peru, was analyzed by combining geographical information systems (GIS) data, census information, and data collected from different sources. Application of the methodology yielded specific indicators for the physical size of buildings (i.e., gross floor area and number of stories) and their material composition. The overall MS in buildings, in 2007, was estimated at 24.4 million tonnes (Mt), or 47 tonnes per capita. This mass is primarily composed of mineral materials (97.7%), mainly concrete (14.1 Mt), while organic materials (e.g., 0.15 Mt of wood) and metals (e.g., 0.40 Mt of steel) constitute the remaining share (2.3%). Moreover, historical census data and projections were used to evaluate the changes in the MS from 1981 to 2017; showing a 360% increase of the MS in the last 36 years. This study provides essential supporting information for urban planners, helping to provide a better understanding of the availability of resources in the city and its future potential supply for recycling as well as to develop strategies for the management of construction and demolition waste.     

Modeling copper demand in China up to 2050: A business‐as‐usual scenario based on dynamic stock and flow analysis

In this paper, we develop a dynamic stock model and scenario analysis involving a bottom‐up approach to analyze copper demand in China from 2005 to 2050 based on government and related sectoral policies. The results show that in the short‐term, China's copper industry cannot achieve a completely circular economy without additional measures. Aggregate and per capita copper demand are both set to increase substantially, especially in infrastructure, transportation, and buildings. Between 2016 and 2050, total copper demand will increase almost threefold. Copper use in buildings will stabilize before 2050, but the copper stock in infrastructure and transportation will not yet have reached saturation in 2050. The continuous growth of copper stock implies that secondary copper will be able to cover just over 50% of demand in 2050, at best, even with an assumed recycling rate of 90%. Finally, future copper demand depends largely on the lifetime of applications. There is therefore an urgent need to prolong the service life of end‐use products to reduce the amount of materials used, especially in large‐scale applications in buildings and infrastructure.     

Should China subsidize cofiring to meet its 2020 bioenergy target? A spatio‐techno‐economic analysis

China has developed ambitious bioenergy installation targets as part of its broader goals to increase its renewable energy‐generating capacity and decarbonize its economy. A key target feedstock for bioenergy is the 800 million tonnes of agricultural residues that China produces each year. At present, the main financial incentive to support bioenergy generation from agricultural residues is a feed‐in‐tariff provided for bioenergy that is produced by units that take 80% or more of their feedstock energy from biomass. Although this policy has catalysed the construction of many bioenergy units, there are reports that these projects are experiencing serious financial and technical problems, leading to low operational efficiency and even closure. An alternative option for China's agricultural residues is cofiring with coal in existing power stations. However, this is currently unprofitable for power station operators, as cofiring is not eligible for financial assistance through the bioenergy feed‐in‐tariff. In the light of China's ambitious target to install 30GW of bioenergy generation capacity by 2020, this study investigates the extent to which extension of the bioenergy feed‐in‐tariff to include cofiring could contribute towards this goal. The results suggest that 39% of China's straw energy resources are located within 50 km of a power station. Assuming cofiring ratios of up to 10% coal energy replacement, an annual 89–117TWh of electricity could be generated by cofiring agricultural residues collected within 50 km radii of power stations. If China extends its bioenergy subsidies to include cofiring, an annual 62–92TWh can be produced at an internal rate of return of 8% or more. This equates to 42–62% of the bioenergy generation that China might expect if it met its 2020 target of installing 30GW of bioenergy capacity. Overall, this indicates a strong case for the Chinese government to extend its existing bioenergy feed‐in‐tariff to include cofiring at low energy replacement ratios.