A High‐Resolution Approach to Mapping Energy Flows through Water Infrastructure Systems

Using data from the water service area of the East Bay Municipal Utility District in Northern California, we develop and discuss a method for assessing, at a high resolution, the energy intensity of water treated and delivered to customers of a major metropolitan water district. This method extends previous efforts by integrating hourly data from supervisory control and data acquisition systems with calculations based on the actual structure of the engineered infrastructure to produce a detailed understanding of energy use in space and time within the territory of a large‐scale urban water provider. We found significant variations in the energy intensity of delivered potable water resulting from seasonal and topographic effects. This method enhances our understanding of the energy inputs for potable water systems and can be applied to the entire delivery and postuse water life cycle. A nuanced understanding of water's energy intensity in an urban setting enables more intelligent, targeted efforts to jointly conserve water and energy resources that take seasonal, distance, and elevation effects into account.     

The current and potential role of urban metabolism studies to analyze the role of food in urban sustainability

Food supply chains are essential for urban sustainability. To reflect on the state of knowledge on urban food flows in urban metabolism research, and the actual and potential role of urban metabolism studies to tackle food sustainability in cities, we systematically review scientific research on food from an urban metabolism perspective and apply statistical and thematic analyses. The analysis of 89 studies provides insights as to the relation between food supply and (environmental and social dimensions of) urban sustainability. First, food is an important contributor to urban environmental impacts, if a consumption-based approach is adopted. Secondly, the social impacts of urban food supply remain scarcely studied in urban metabolism research, but emerging results on public health, malnutrition, and food waste appear promising. In parallel, we find that the findings of the studies fail to engage with debates present in the broader literature, such as that of food justice. Our analysis shows that most studies focus on large cities in high-income, data-rich countries. This limits our understanding of global urban food supply. Existing studies use innovative mixed-methods to produce robust accounts of urban food flows in data-scarce contexts; expanding these accounts is necessary to get a better understanding of how urban food supply and its diverse impacts in terms of environmental and social sustainability may vary across cities, a necessary step for the urban metabolism literature to contribute to current debates around food sustainability and justice.     

Comparing urban food system characteristics and actions in US and Indian cities from a multi‐environmental impact perspective: Toward a streamlined approach

Food action plans in many global cities articulate interest in multiple objectives including reducing in‐ and trans‐boundary environmental impacts (water, land, greenhouse gas (GHG)). However, there exist few standardized analytical tools to compare food system characteristics and actions across cities and countries to assess trade‐offs between multiple objectives (i.e., health, equity) with environmental outcomes. This paper demonstrates a streamlined model applied for analysis of four cities with varying characteristics across the United States and India, to quantify system‐wide water, energy/GHG, and land impacts associated with multiple food system actions to address health, equity, and environment. Baseline diet analysis finds key differences between countries in terms of meat consumption (Delhi 4; Pondicherry 16; United States 59, kg/capita/year), and environmental impact of processing of the average diet (21%, 19%, <1%, <1% of community‐wide GHG‐emissions for New York, Minneapolis, Delhi, and Pondicherry). Analysis of supply chains finds city average distance (food‐miles) varies (Delhi 420; Pondicherry 200; United States average 1,640 km/t‐food) and the sensitivity of GHG emissions of food demand to spatial variability of energy intensity of irrigation is greater in Indian than US cities. Analysis also finds greater pre‐consumer waste in India versus larger post‐consumer accumulations in the United States. Despite these differences in food system characteristics, food waste management and diet change consistently emerge as key strategies. Among diet scenarios, all vegetarian diets are not found equal in terms of environmental benefit, with the US Government's recommended vegetarian diet resulting in less benefit than other more focused targeted diet changes.     

Integrating lifecycle assessment and urban metabolism at city level: Comparison between Spanish cities

Urban systems are important consumers of resources and producers of wastes derived from the lifestyles and daily needs of their citizens. The quantification of environmental impacts arising from urban metabolism (UM) plays a key role in the design of more sustainable cities and in the development of decision‐making strategies into more effective urban policies. This article combines UM and lifecycle assessment methodology to quantify mass and energy flows within the city limits and derived urban environmental pressures, thus prioritizing the environmental perspective of sustainability. This methodology is applied to the two very different Spanish cities of Bilbao and Seville. The results acquired in this study identify the consumption of construction materials, electricity, fossil fuels, and food and beverages as environmental hotspots. The results are primarily affected by differences in the climate (extreme conditions), which mainly affect the consumption of fossil fuels, and differences in purchasing power, which mainly influence the intake of foodstuffs. Further research should focus on data management and quality as well as on designing more efficient cities (e.g., through the introduction of more energy‐efficient buildings, sustainable building materials, and public transport) in order to create improvements in their environmental profiles.     

Reunderstanding Cairo through urban metabolism: Formal versus informal districts resource flow performance in fast urbanizing cities

Urban expansion can be seen as the most pervasive human impact on the environment where its high resource use contributes negatively to climate change and resource scarcity crises. Many experts call for decoupling resource use, economic development, and related urban development especially within cities of the Global South. This paper focuses on investigating resource efficiency through the lens of urban metabolism. It investigates current resource flows, through material flow analysis, from source to sink, in two diverse districts in Cairo: a formal district and an informal one, regarding materials (waste) and mobility. Consequently, the paper discusses locally responsive interventions that address local priorities as opposing to citywide one‐size fits all solution. The paper relies on parcel audits, which are embedded in an Urban Metabolism Information System developed by the Ecocity Builders and their partners, through a joint project with Cairo University. The methodology couples crowd‐sourced data, parcel audits, and experts’ knowledge to better understand resource flows based on a bottom‐up approach, given the unavailability of governmental data on the local level. The paper further correlates the perceived quality of life with the actual resource flows. It utilizes fieldwork investigations to argue against the local misconceptions regarding the inefficiency of informal areas/systems versus the higher efficiency of planned areas/systems. The paper concludes by proposing integrated solutions that respond to local needs and resources. It highlights the challenges and lessons of this tailored bottom‐up approach and its applicability in other cities worldwide.     

Quantifying a virtual water metabolic network of the Metropolitan District of Quito,Ecuador using ecological network methods

Current human population is mostly located in urban areas making cities the center of attention in terms of achieving sustainability goals. Evidence shows that ecosystems have evolved over time toward a balanced configuration between resource efficiency and functional redundancy. For this reason, they are exemplary models to follow in terms of sustainability. Here, we apply similar ecological network-based methods to study the virtual water metabolic network (VWMN) of the Metropolitan District of Quito. The VWMN was obtained using novel bottom-up, survey-based methods to generate the urban metabolic network. We compare the VWMN results with those previously obtained from ecological food webs, to learn if there are insights about the sustainability of urban metabolic processes. We conclude that VWMN does not exhibit characteristics observed in sustainable ecological networks because this socioeconomic network exhibits higher levels of path redundancy. Urban metabolism studies are gaining in popularity as a research tool aimed at informing resource management and this is one of the first covering a city in the Global South and using a bottom-up survey method.     

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.     

Drivers of urban metabolism: Toward a framework for urban transformations

The environmental and social crises in cities call for radical future visions that can incite transformative change. Yet, urban metabolism research typically adopts an explanatory, retrospective approach to the drivers of urban flows and stocks, resulting in conservative, business-as-usual future outlooks. In this study, we present the results of a narrative literature review on drivers and futures of urban metabolism, and consequently use these results to propose and apply a framework that can be used by researchers (i) to systematically identify the drivers of urban metabolism, and (ii) to critically engage with these drivers for the development of transformative future visions. The framework comprises seven thematic categories of drivers (demographic, economic, cultural, political, technological, environmental, and infrastructural) and an eighth category (power) to be used as the lens through which the interactions between drivers, activities, and flows in the city are critically examined. Applying the framework to the case study of biowaste management in Rennes, France, we found it useful for the systematic identification of often overseen drivers. The proposed framework, allowing for a combined analysis of flows and drivers, can become a useful tool toward a solution-oriented urban metabolism research.     

The Changing Metabolism of Cities

Data from urban metabolism studies from eight metropolitan regions across five continents, conducted in various years since 1965, are assembled in consistent units and compared. Together with studies of water, materials, energy, and nutrient flows from additional cities, the comparison provides insights into the changing metabolism of cities. Most cities studied exhibit increasing per capita metabolism with respect to water, wastewater, energy, and materials, although one city showed increasing efficiency for energy and water over the 1990s. Changes in solid waste streams and air pollutant emissions are mixed.
The review also identifies metabolic processes that threaten the sustainability of cities. These include altered ground water levels, exhaustion of local materials, accumulation of toxic materials, summer heat islands, and irregular accumulation of nutrients. Beyond concerns over the sheer magnitudes of resource flows into cities, an understanding of these accumulation or storage processes in the urban metabolism is critical. Growth , which is inherently part of metabolism, causes changes in water stored in urban aquifers, materials in the building stock, heat stored in the urban canopy layer, and potentially useful nutrients in urban waste dumps.
Practical reasons exist for understanding urban metabolism. The vitality of cities depends on spatial relationships with surrounding hinterlands and global resource webs. Increasing metabolism implies greater loss of farmland, forests, and species diversity; plus more traffic and more pollution. Urban policy makers should consider to what extent their nearest resources are close to exhaustion and, if necessary, appropriate strategies to slow exploitation. It is apparent from this review that metabolism data have been established for only a few cities worldwide, and interpretation issues exist due to lack of common conventions. Further urban metabolism studies are required.     

Comparison of U.S. and Japanese Consumers’ Perceptions of Remanufactured Auto Parts

This study compares U.S. and Japanese consumers’ perceptions of remanufactured auto parts. Remanufactured parts have a long history and enjoy continuing success in the U.S. domestic aftermarket. In contrast, although Japan's domestic aftermarket is growing, it remains comparatively underdeveloped. This research examines whether customers’ perceptions of remanufactured products explain their lower acceptance in Japan. Our Internet survey of 440 U.S. and 300 Japanese respondents examined their knowledge of remanufactured auto parts, perceptions of their benefits and risks, and price consciousness. The results reveal that Japanese consumers know less about remanufactured products, perceiving them as entailing lower benefits and greater risk, especially concerning quality, and are less price conscious. Drawing on its results, this study suggests measures to promote markets for remanufactured auto parts in Japan and in economies in which such markets are in an early stage of development.     

Net Zero Fort Carson: Integrating Energy,Water, and Waste Strategies to Lower the Environmental Impact of a Military Base

Military bases resemble small cities and face similar sustainability challenges. As pilot studies in the U.S. Army Net Zero program, 17 locations are moving to 100% renewable energy, zero depletion of water resources, and/or zero waste to landfill by 2020. Some bases target net zero in a single area, such as water, whereas two bases, including Fort Carson, Colorado, target net zero in all three areas. We investigated sustainability strategies that appear when multiple areas (energy, water, and waste) are integrated. A system dynamics model is used to simulate urban metabolism through Fort Carson's energy, water, and waste systems. Integrated scenarios reduce environmental impact up to 46% from the 2010 baseline, whereas single‐dimension scenarios (energy‐only, water‐only, and waste‐only) reduce impact, at most, 20%. Energy conserving technologies offer mutual gains, reducing annual energy use 18% and water use 15%. Renewable energy sources present trade‐offs: Concentrating solar power could supply 11% of energy demand, but increase water demand 2%. Waste to energy could supply 40% of energy demand and reduce waste to landfill >80%, but increase water demand between 1% and 22% depending on cooling system and waste tonnage. Outcomes depend on how the Fort Carson system is defined, because some components represent multiple net zero areas (food represents waste and energy), and some actions require embodied resources (energy generation potentially requires water and off‐base feedstock). We suggest that integrating multiple net zero goals can lead to lower environmental impact for military bases.     

A Spatial Analysis of Residential Greenhouse Gas Emissions in the Toronto Census Metropolitan Area

Residential greenhouse gas (GHG) emissions in the Toronto Census Metropolitan Area are spatially analyzed to determine the impact of urban form on emission-causing activities. The key finding is that over the entire region, emissions from private auto use are on par with those from fuel use for building heating. Once beyond the transit-intensive central core, private auto emissions surpass the emissions from building operations. Variation in total auto- and building-related emissions is quite significant between census tracts, ranging from 3.1 to 13.1 tonnes of carbon dioxide equivalents per year. Of all tracts, the top ten in terms of GHG emission are located in the lower-density suburbs, and their high emissions were largely due to private auto use.     

Urban Metabolism and the Energy Stored in Cities

Using the city of Toronto as a case study, this article examines impacts of energy stocks and flexible demand in the urban metabolism on the resilience of the city, including discussion of directions for further study of the resiliency of the urban metabolism. An important element developed is the nominal residence time of the energy stocks. This value defines how long an energy stock lasts under typical patterns of energy use. The findings suggest that the residence times of many sources of energy overcome vulnerability when energy supply shocks last on the order of hours or a few days, but that the measure is limited to assessing only certain types of commonly used energy sources in aggregate terms. Discussion is included on the uncertainty of this measure and on the metabolic and resiliency implications of new technologies intended to reduce energy use and improve sustainability of cities and the use of the urban metabolism as a means of comparison. The methodology employed highlights how waste energy could be used to increase the resiliency of the city's water supply, but also how the study of the urban metabolism would benefit from a more disaggregate form in the study of sustainable and resilient cities.     

Unraveling the Nexus: Exploring the Pathways to Combined Resource Use

In response to the unprecedented decline in global natural resource endowments, the so‐called nexus framework is gaining increasing influence on resource management practices. In this research, we approach the resource nexus through the concept of nexus pathways. Nexus pathways are configurations that resource flows follow along supply chains leading to the combined use of two or more resources. Three general types of pathways are identified: direct (on‐site use), dependent (one‐way supply chains), and interdependent (supply‐chain feedbacks). We quantify and compare each pathway by means of multiregional input‐output analysis and structural path analysis, and apply this approach to a comparative case study on the water‐energy nexus (WEN) in the United States and China. Interdependencies or feedbacks are generally thought to be relevant for the WEN, especially between water and energy sectors. Our economy‐wide analysis for both countries indicates, however, that feedbacks neither play an important role in the WEN nor substantially take place between water and energy sectors. The most important feedbacks contribute to less than 1% of total resource use, and these take place mostly between manufacturing sectors. Overall, the studied WEN is mostly driven by dependent pathways and, to a lesser degree, direct resource use. Comparative differences between the two countries are largely explained by differences in economic structure, technology, and resource endowments. Our findings call into question current research and policy focus and suggest greater attention to less complex, but more determining, pathways leading to absolute resource use.     

Decomposition of Toxic Chemical Substance Management in Three U.S. Manufacturing Sectors from 1991 to 2008

This study analyzes toxic chemical substance management in three U.S. manufacturing sectors from 1991 to 2008. Decomposition analysis applying the logarithmic mean Divisia index is used to analyze changes in toxic chemical substance emissions by the following five factors: cleaner production, end‐of‐pipe treatment, transfer for further management, mixing of intermediate materials, and production scale. Based on our results, the chemical manufacturing sector reduced toxic chemical substance emissions mainly via end‐of‐pipe treatment. In the meantime, transfer for further management contributed to the reduction of toxic chemical substance emissions in the metal fabrication industry. This occurred because the environmental business market expanded in the 1990s, and the infrastructure for the recycling of metal and other wastes became more efficient. Cleaner production is the main contributor to toxic chemical reduction in the electrical product industry. This implies that the electrical product industry is successful in developing a more environmentally friendly product design and production process.     

Public health measures and mortality in U.S. cities in the late nineteenth century

In this paper we examine the decline in mortality rates by cause of death in U.S. cities during the last decade of the. 19th century. Causes of death are grouped according to their probable relationship to specific public health measures. The reduction which occurred in the death rates from some diseases, e.g., typhoid and diarrheal diseases, can probably be attributed in part to the provision of sewers and waterworks. Large declines also occurred in the death rates from tuberculosis and diphtheria, but the relationship between the declines in these diseases and public health practices designed to combat them is more ambiguous. We therefore conclude that public health measures had some impact on the decline in mortality, but that these measures do not provide a complete explanation of the mortality decline.The research on which this paper is based was supported by NICHD Grant 1-R01-HD-05427. A version of this article was presented at the meetings of the American Sociological Association, New York, August 30–September 3, 1976.     

The Nexus of Carbon,Nitrogen, and Biodiversity Impacts from Urban Metabolism

Methodology is developed for linking the urban metabolism (UM) to global environmental stresses on the carbon (C) cycle, nitrogen (N) cycle, and biodiversity loss. UM variables are systematically mapped to the drivers of carbon, nitrogen, and biodiversity impacts. Change in mean species abundance is used as metric of biodiversity loss, by adopting the dose‐response relationships from the GLOBIO model. The main biodiversity drivers related to UM included here are land‐use change (LUC) and atmospheric N deposition. The methodology is demonstrated by studying the nexus for Shanghai in 2006, based on energy and soybean consumption. Results for Shanghai show a strong nexus between C, N, and biodiversity impact due to electricity consumption and energy used in manufacturing industries and construction. Prioritization of the shift away from coal energy will therefore lead to lowering the urban growth impact on all three dimensions. Road transportation, domestic aviation, and the metal industry impact only the C footprint highly, whereas district energy impacts only biodiversity loss highly, showing a weak nexus. Among the global impacts of soybean consumption in Shanghai on biodiversity loss (due to LUC only), the highest impact occurs in Uruguay (0.52%) followed by Brazil (0.05%) and Argentina (0.02%). The local impact on biodiversity loss (i.e., within China) of soybean consumption in Shanghai is 1.03%. However, the methodology and results are limited due to the partial inclusion of drivers, a carbon footprint based on carbon dioxide emissions only, and limitations of biodiversity loss models. Potential to overcome methodological limitations is discussed.     

From the urban metabolism to the urban immune system

Urban areas face mounting risks from many sources. Cities pursue myriad tactics to resist, recover from and adapt to shocks and stresses, but little is known about how these approaches relate across the scales of a city nor how cities compare in their abilities. Part of the challenge in addressing these gaps is that the risk to cities is typically studied with an emphasis on one or a few hazards or through the lens of a singular sector. This paper proposes a framework, dubbed the Urban Immune System (UIS) to coalesce and expand industrial ecology research on urban risk management. In the same way that Urban Metabolism (UM) is a unifying framework for urban environmental sustainability, UIS can be a unifying framework for urban resilience, especially related to climate change. Herein, UIS is defined, its many capabilities are dissected and linked to disparate studies; and opportunities for application of the concept are provided. The paper concludes by examining the relationship between UIS and climate change and by identifying those attributes of the UIS that are expected to be of increasing importance under climate change.     

转型期城市生态学前沿研究进展

城市是一类以人类活动为中心听社会－经济－自然复合生态系统。城市人类活动对局地、区域和全球环境的胁迫效应,自然生态系统的响应机制,城市时、空、量、构、序的耦合规律、动力学机制和控制论方法是当前国际社会和学术界关注的热点。介绍了转型期城市人类生态影响研究的一些主要国际科学计划,如ＳＣＯＰＥ及ＩＨＤＰ等,综述了城市生态学研究三大前沿领域的国际研究动向和案例,即人居生态学、产业生态学和城镇生命支持系统生态