Applying Ecological Input-Output Flow Analysis to Material Flows in Industrial Systems

This article, continuing with the themes of the companion article, expounds the capabilities of input-output techniques as applied to material flows in industrial systems. Material flows are the primary focus because of their role in directly linking natural and industrial systems and thereby being fundamental components of environmental issues in industrial economies. The specific topic in this article concerns several material flow metrics used to characterize system behavior that are derived from the ecological development of input-output techniques; most notable of these metrics are several measures of material cycling and a measure of the number of processes visited by material while in a system. These metrics are shown to be useful in analyzing the state of material flow systems. Further-more, the metrics are shown to be a central link in connecting input-output flow analysis to synthesis (i.e., the process of using measurements of system behavior to design changes to that system). By connecting the flow metrics to both environmental objectives and controllable aspects of flow models, changes to existing flow systems are synthesized to generate improved system behavior. To bring this pair of articles to a close, several limitations of input-output flow analysis are summarized with the goal of stimulating further interest and research.     

Applying Ecological Input-Output Flow Analysis to Material Flows in Industrial Systems: Part I: Tracing Flows

Input-output mathematics, which allows a modeler to fully consider direct and indirect relationships among conserved flows in a system, has a long history in economics with prominent use dating to Leontief in the 1930s. Nearly all previous industrial applications of input-output analysis have been grounded in the monetary flows of an economy. Here however, because of the central nature of physical flows in the environmental impact of industry, we consider physical flows to be a fundamental component of an industrial economy. Hence, we propose an input-output based approach for modeling physical flows in industry independent of their monetary implications.
In this first part of a two-part article, a framework for using input-output mathematics to model material and energy flows is constructed from a foundation laid by previous research in nutrient and energy cycling in natural ecosystems. The mathematics of input-output flow analysis is presented from an ecological perspective, culminating in two core capabilities: tracing of flows with environs (investigated in this article) and characterizing system behavior with flow metrics (presented in the second article). We assert that environ analysis is an effective means for tracing flows through industrial systems while fully considering direct and indirect flow paths. We explore material flows of aluminum and five other metals in depth using environ analysis in this article.     

Approaches for Quantifying the Metabolism of Physical Economies: Part I: Methodological Overview

This article is the first of a two-part series that describes and compares the essential features of nine existing "physical economy" approaches for quantifying the material demands of the human economy upon the natural environment. A range of material flow analysis (MFA) and related techniques is assessed and compared in terms of several major dimensions. These include the system boundary identification for material flow sources, extents, and the key socioinstitutional entities containing relevant driving forces, as well as the nature and detailing of system components and flow interconnections, and the comprehensiveness and types of flows and materials covered.
Shared conceptual themes of a new wave of physical economy approaches are described with a brief overview of the potential applications of this broad family of methodologies. The evolving and somewhat controversial nature of the characteristics and role that define MFA is examined. This review suggests the need to specify whether MFA is a general metabolic flow measurement procedure that can be applied from micro to macrolevels of economic activity, or a more specific methodology aimed primarily at economy-wide analyses that "map" the material relations between society and nature. Some alternative options for classifying MFA are introduced for discussion before a more detailed comparative summary of the key methodological features of each approach in the second part of this two-part article.
The review is presented (1) as a reference and resource for the increasing number of policy makers and practitioners involved in industrial ecology and the evaluation of the material basis of economies and the formulation of eco-efficiency strategies, and (2) to provoke discussion and ongoing dialogue to clarify the many existing areas of discordance in environmental accounting related to material flows, and help consolidate the methodological basis and application of MFA.     

Approaches for Quantifying the Metabolism of Physical Economies: A Comparative Survey: Part II: Review of Individual Approaches

This article is the second of a two-part series that describes and compares the essential features of nine "physical economy" approaches for mapping and quantifying the material demands of the human economy upon the natural environ-ment. These approaches are critical tools in the design and implementation of industrial ecology strategies for greater eco-efficiency and reduced environmental impacts of human economic activity. Part I of the series provided an overview, meth-odological classification, and comparison of a selected set of major materials flow analysis (MFA) and related techniques. This sequel includes a convenient reference and overview of the major metabolism measurement approaches in the form of a more detailed summary of the key specific analytical and other features of the approaches introduced in part I. The surveyed physical economy related environmental analysis ap-proaches include total material requirement and output mod-els, bulk MFA (IFF (Department of Social Ecology, Institute for Interdiscplinary Studies of Austrian Universities) material flow balance model variant), physical input-output tables, substance flow analysis, ecological footprint analysis, environmental space, material intensity per unit service, life-cycle assessment (LCA), the sustainable process index, and company-level MFA.     

Multilevel Anthropogenic Cycles of Copper and Zinc: A Comparative Statistical Analysis

Contemporary cycles for copper and zinc are coanalyzed with the tools of exploratory data analysis. One-year analyses (circa 1994) are performed at three discrete spatial levels-country (52 countries that comprise essentially all anthropogenic stocks and flows of the two metals), eight world regions, and the planet as a whole-and are completed both in absolute magnitude and in per capita terms. This work constitutes, to our knowledge, the first multiscale, multilevel analysis of anthropogenic resources throughout their life cycles. The results demonstrate that (1) A high degree of correlation exists between country-level copper and country-level zinc rates of fabrication and manufacturing, entry into use, net addition to in-use stocks, discard, and landfilling; (2) Regional-level rates for copper and zinc cycle parameters show the same correlations as exist at country level; (3) On a per capita basis, countries add to in-use stock almost 50% more copper than zinc; (4) The predominant discard streams for copper and zinc at the global level are different for the two metals, and relative rates of different loss processes differ geographically, so that resource recovery policies must be designed from metalspecific and location-specific perspectives; (5)When absolute magnitudes of life-cycle flows are considered, the standard deviations of the data sets decrease from country level to regional level for both copper and zinc, which is not the case for the per capita data sets, where the statistical properties of the data sets for both metals approach being independent of spatial level, thus providing a basis for predicting unmeasured per capita metal flow behavior.     

Modeling Basic Industries in the Australian Stocks and Flows Framework

The Australian stocks and flows framework (ASFF) is a tool for establishing a coherent historical picture of the Australian physical economy and for testing long-term future scenarios (up to 2050 or even 2100). These scenarios can be used to investigate the long-term physical consequences of current and future choices affecting the physical dimensions of sustainability. In this article we describe the methodology for and construction of a key component of ASFF: a dynamic physical input-output model of material flows in the basic industries.
The materials model in ASFF describes physical flows and their transformation by industrial processes. The model's structure permits scenario analysis of long-term technological change by permitting time-varying input-output coefficients and vintage models of capital stocks. As a consequence, the model contains a large number of parameters, which can be left at default settings or adjusted as the modeler sees fit, in order to simulate the widest possible range of physically realizable scenarios. The materials model is built using a methodology that integrates bottom-up process analysis with top-down statistics on material and energy flows. We present some examples showing how the materials model has been implemented to model Australian heavy industries. Several possibilities for further developing the materials model are also described.     

Exploratory Data Analysis of the Multilevel Anthropogenic Zinc Cycle

A comprehensive multilevel contemporary cycle for stocks and flows of zinc is analyzed by the tools of exploratory data analysis. The analysis is performed at three discrete organizational levels—country (53 countries and 1 country group that together comprise essentially all anthropogenic stocks and flows of zinc), world region (9 world regions), and the planet as a whole. The results demonstrate the following: (1) Exploratory data analysis provides valuable and otherwise unobtainable information about material flows, especially those across multiple spatial levels. (2) All distributions of countrylevel zinc stock and flow data are highly skewed, a few countries having large magnitudes, many having small magnitudes. Rates of fabrication of zinc-containing products for the countries are poorly correlated with rates of extraction, reflecting the fact that many countries that extract zinc do not fabricate products from zinc to any significant degree, and vice versa. (4) Virtually all countries are adding zinc to stock in the use phase (in galvanizing applications, zinc castings, etc.). These rates of addition are highly correlated with rates of zinc entering use in all regions, and are higher in regions under vigorous development. (5) With weak confidence, the rate of zinc landfilling by countries appears to be highly correlated with the rate of discard. (6) The statistical distributions of regional-level zinc cycle parameters are approximately log normal. (7) The extremes of normalized statistical distributions of zinc flow values are broader at lower spatial levels (country versus region, for example), but regional interquartile ranges for zinc entering use and zinc discards are higher at regional level then at country level.     

物质流分析研究述评

物质流分析方法近年来在循环经济和可持续发展研究领域发展迅速。阐述了物质流分析的定义及其与自然生态系统物质流的区别,着重回顾了该研究方法的发展历程,阐明了物质流分析的主要观点、理论基础、研究思路及研究框架,详细阐译和对比分析了物质流分析的六大类指标及分析方法,并在物质流分析框架的基础上,建立循环经济及可持续发展的评价指标体系,并对物质流分析指标体系和方法学的研究意义及其在环境经济学中的地位进行了客观的评价,进而指出了物质流分析方法的不足之处。对物质流分析在不同层次的应用研究也进行了充分的阐述和分析。对物质流分析今后相关领域的进一步研究予以了讨论和展望。     

Society's Metabolism

"Societal metabolism" provides the appropriate conceptual basis for the rapidly growing development and analylical and policy interest in materials flow analysis (MFA). Following the review of the earlier intellectual background of societal metabolism in the first installment of this two-part article, this paper focuses on the current state of the art by examining more recent research referring t o societal metabolism in terms of material and substance flows. An operational classification of the literature according to frame of reference (socioeconomic system, ecosystem), system level (global, national, regional, functional, temporal), and types of flows under consideration (materials, energy, substances) highlights some of its characteristic features. There follows an integrated discussion of some of the major conceptual and methodological properties of MFA, with a particular focus on the field of bulk materials flows on a national level, comparing the major empirical results. Finally, the theoretical stringency research productivity, and political relevance of the MFA-related studies are assessed.     

磷元素物质流分析研究进展

磷是重要的营养元素,也是不可再生的重要非金属矿物资源。为了分析人类活动对磷流动的扰动,国内外开展了大量磷元素的物质流分析和模拟。综述了磷元素物质流分析的最新研究进展,分析了国内外磷元素物质流研究的特点和不足,并展望了未来相关研究的研究热点和发展方向。从研究尺度看,现有磷元素的物质流研究以全球尺度和国家尺度为主,区域和城市尺度以及企业和产品尺度的研究较少。从研究问题看,现阶段研究主要关注农业或者食品生产和消费对磷流动的影响,对林业、钢铁和能源部门略有涉及。从模型特征看,现有研究以分析流量变化的静态模型为主,考虑存量变化的动态模拟较少。从研究的发展方向看,未来磷物质流的相关分析将关注五大问题:(1)考虑不同驱动力和存量变化的动态模拟;(2)不同层次和尺度的磷足迹研究;(3)磷与其他元素相比对社会经济的重要性;(4)全球变化背景下不同部门磷依赖的脆弱性;(5)磷和其他元素的耦合研究。为了适应未来的研究需求,磷的物质流模拟重点在于开发动态模型,并将物质流分析与多种手段结合,以预测全球变化、社会经济发展、技术变化以及其他重要变化对磷流动的扰动及其相应的环境影响。     

The Temporal Evolution of Anthropogenic Phosphorus Consumption in China and Its Environmental Implications

Modern human activities greatly disturb substance flows in nature and senselessly discard massive amounts of precious resources to natural waste reservoirs; phosphorus (P) is a good example of this. In this article, substance flow analysis is employed to quantify and explore the temporal evolution of China's P consumption in main metabolic nodes from 1984 to 2008, and then the environmental implications for P flows into both surface waters and natural soil are investigated. Results show that the metabolic nodes of human life and animal husbandry have demanded increasingly more P inputs, while disseminating more and more P wastes, with the waste recycling ratios of these processes dropping, respectively, from 65.9% and 66.1% in 1984 to 50.7% and 40.6% by 2008. These change traits were closely related to national polices including the Household Contract Responsibility System and the Shopping Basket Program, as well as the policy vacuum existing between China's agricultural and environmental administration departments. To achieve high crop yield, increasingly more inorganic P fertilizers have been utilized in China, but their use efficiency has decreased by 46.3%. From 2003 to 2008, the total P load into surface waters was stabilized at about 900.0 kilotons (kt), while the total P load into natural soil increased by more than 3.8 times to 3,131.3 kt P in 2008. City life and the intensive breeding of crops are identified as the main targets for further pollution control and nutrient recycling in China. Some suggestions for achieving environmentally sound practices and resource sustainability in China are proposed at the end of this article.     

A Material Flow Accounting Case Study of the Lisbon Metropolitan Area using the Urban Metabolism Analyst Model

This article describes a new methodological framework to account for urban material flows and stocks, using material flow accounting (MFA) as the underlying method. The proposed model, urban metabolism analyst (UMAn), bridges seven major gaps in previous urban metabolism studies: lack of a unified methodology; lack of material flows data at the urban level; limited categorizations of material types; limited results about material flows as they are related to economic activities; limited understanding of the origin and destination of flows; lack of understanding about the dynamics of added stock; and lack of knowledge about the magnitude of the flow of materials that are imported and then, to a great extent, exported. To explore and validate the UMAn model, a case study of the Lisbon Metropolitan Area was used. An annual time series of material flows from 2003 to 2009 is disaggregated by the model into 28 material types, 55 economic activity categories, and 18 municipalities. Additionally, an annual projection of the obsolescence of materials for 2010–2050 was performed. The results of the case study validate the proposed methodology, which broadens the contribution of existing urban MFA studies and presents pioneering information in the field of urban metabolism. In particular, the model associates material flows with economic activities and their spatial location within the urban area.     

Combining Material Flow Analysis,Life Cycle Assessment,and Multiattribute Utility Theory

Three assessment methods, material flow analysis (MFA), life cycle analysis (LCA), and multiattribute utility theory (MAUT) are systematically combined for supporting the choice of best end‐of‐life scenarios for polyethylene terephthalate (PET) waste in a municipality of a developing country. MFA analyzes the material and energy balance of a firm, a region, or a nation, identifying the most relevant processes; LCA evaluates multiple environmental impacts of a product or a service from cradle to grave; and MAUT allows for inclusion of other aspects along with the ecological ones in the assessment. We first systematically coupled MFA and LCA by defining “the service offered by the total PET used during one year in the region” as the functional unit. Inventory and impacts were calculated by multiplying MFA flows with LCA impacts per kilogram. We used MAUT to include social and economic aspects in the assessment. To integrate the subjective point of view of stakeholders in the MAUT, we normalized the environmental, social, and economic variables with respect to the magnitude of overall impacts or benefits in the country. The results show large benefits for recycling scenarios from all points of view and also provide information about waste treatment optimization. The combination of the three assessment methods offers a powerful integrative assessment of impacts and benefits. Further research should focus on data collection methods to easily determine relevant material flows. LCA impact factors specific to Colombia should be developed, as well as more reliable social indicators.     

Towards an Integrated Regional Materials Flow Accounting Model

A key challenge in attaining regional sustainability is to reduce both the direct and the indirect environmental impacts associated with economic and household activity in the region. Knowing what these flows are and how they change over time is a prerequisite for this task.
This article describes the early development of an integrated regional materials flow accounting framework. The framework is based on a hybrid (material and economic) multiregional input-output model. Using readily available economic and materials data sets together with transport and logistics data, the framework attempts to provide estimates of household resource flows for any U.K. region at quite detailed levels of product and material disaggregation. It is also capable of disaggregating these flows according to specific socioeconomic criteria such as income level or occupation of the head of household. Allied to appropriate energy and life-cycle assessment data sets, the model could, in addition, be used to map both direct and indirect environmental impacts associated with these flows.
The benefits of such an approach are likely to be a considerable reduction of uncertainties in (1) our knowledge of the household metabolism, and hence our predictions of regional household waste generation; (2) our assessment of the impacts of contemplated changes in industrial process siting, and thereby on other aspects of local and regional planning; and (3) our understanding of the impacts of changes in the pattern of demand for different materials and products. It is concluded that the use of such an integrated assessment tool has much to contribute to the debate on regional sustainability.     

Rationale for and Interpretation of Economy-Wide Materials Flow Analysis and Derived Indicators

Economy-wide material flow analysis (MFA) and derived indicators have been developed to monitor and assess the metabolic performance of economies, that is, with respect to the internal economic flows and the exchange of materials with the environment and with other economies. Indicators such as direct material input (DMI) and direct material consumption (DMC) measure material use related to either production or consumption. Domestic hidden flows (HF) account for unused domestic extraction, and foreign HF represent the upstream primary resource requirements of the imports. DMI and domestic and foreign HF account for the total material requirement (TMR) of an economy. Subtracting the exports and their HF provides the total material consumption (TMC).
DMI and TMR are used to measure the (de-) coupling of resource use and economic growth, providing the basis for resource efficiency indicators. Accounting for TMR allows detection of shifts from domestic to foreign resource requirements. Net addition to stock (NAS) measures the physical growth of an economy. It indicates the distance from flow equilibrium of inputs and outputs that may be regarded as a necessary condition of a sustainable mature metabolism.
We discuss the extent to which MFA-based indicators can also be used to assess the environmental performance. For that purpose we consider different impacts of material flows, and different scales and perspectives of the analysis, and distinguish between turnover-based indicators of generic environmental pressure and impact-based indicators of specific environmental pressure. Indicators such as TMR and TMC are regarded as generic pressure indicators that may not be used to indicate specific environmental impacts. The TMR of industrial countries is discussed with respect to the question of whether volume and composition may be regarded as unsustainable.     

Unified Materials Information System (UMIS): An Integrated Material Stocks and Flows Data Structure

Modern society depends on the use of many diverse materials. Effectively managing these materials is becoming increasingly important and complex, from the analysis of supply chains, to quantifying their environmental impacts, to understanding future resource availability. Material stocks and flows data enable such analyses, but currently exist mainly as discrete packages, with highly varied type, scope, and structure. These factors constitute a powerful barrier to holistic integration and thus universal analysis of existing and yet to be published material stocks and flows data. We present the Unified Materials Information System (UMIS) to overcome this barrier by enabling material stocks and flows data to be comprehensively integrated across space, time, materials, and data type independent of their disaggregation, without loss of information, and avoiding double counting. UMIS can therefore be applied to structure diverse material stocks and flows data and their metadata across material systems analysis methods such as material flow analysis (MFA), input‐output analysis, and life cycle assessment. UMIS uniquely labels and visualizes processes and flows in UMIS diagrams; therefore, material stocks and flows data visualized in UMIS diagrams can be individually referenced in databases and computational models. Applications of UMIS to restructure existing material stocks and flows data represented by block flow diagrams, system dynamics diagrams, Sankey diagrams, matrices, and derived using the economy‐wide MFA classification system are presented to exemplify use. UMIS advances the capabilities with which complex quantitative material systems analysis, archiving, and computation of material stocks and flows data can be performed.     

Heavy-Metal Balances, Part II: Management of Cadmium, Copper, Lead, and Zinc in European Agro-Ecosystems

The aim of sustainable heavy-metal management in agroecosystems is to ensure that the soil continues to fulfill its functions: in agricultural production, in environmental processes such as the cycling of elements, and as a habitat of numerous organisms. To understand and manage heavy-metal flows effectively, a consistent approach to modeling the flows is needed within the particular agro-system under study. General aspects of heavy-metal balance studies in agro-ecosystems were described in part I of this study. In this article (part II), several European studies of heavy-metal balances at varying spatial scales and in a variety of agro-ecosystems are reviewed. Sectoral studies at the national and international levels provide information for economic analyses and generic regulations; however, policies implemented at these levels often ignore farm characteristics and individual management options. Field-scale and farm-gate balances give farmers specific feedback on effective options for better heavy-metal management. Heavy-metal balances could be incorporated in an environmental management system of certified farms. In this way, farm certification may well serve as a basis from which to develop policy to address environmental issues in agriculture.     

The Waste Input-Output Approach to Materials Flow Analysis

Abstract: A general analytical model of materials flow analysis (MFA) incorporating physical waste input-output is proposed that is fully consistent with the mass balance principle. Exploiting the triangular nature of the matrix of input coefficients, which is obtained by rearranging the ordering of sectors according to degrees of fabrication, the material composition matrix is derived, which gives the material composition of products. A formal mathematical definition of materials (or the objects, the flow of which is to be accounted for by MFA) is also introduced, which excludes the occurrence of double accounting in economy-wide MFAs involving diverse inputs. By using the model, monetary input-output (IO) tables can easily be converted into a physical material flow account (or physical input-output tables [PIOT]) of an arbitrary number of materials, and the material composition of a product can be decomposed into its input origin. The first point represents substantial saving in the otherwise prohibitive cost that is associated with independent compilation of PIOT. The proposed methodology is applied to Japanese IO data for the flow of 11 base metals and their scrap (available as e-supplement on the JIE Web site).     

An Integrated Computational Infrastructure for a Virtual Tokyo Concepts and Examples

The evaluation of tradeoffs between technologies and policies for mitigation of environmental problems requires a systematic investigation of effects over the entire region under consideration. When attempting to model such large complex systems, issues such as usability, maintenance, and computing efficiency often become major modeling barriers. In this work a software prototype for integrating the services of computational models over the Internet, called DOME (distributed object-based modeling environment) is used to facilitate the construction of virtual Tokyo—a simulation platform for evaluating holistically the tradeoffs between various technologies for reducing the emissions of greenhouse gases. In making steps toward this ultimate goal, two models have been developed that use data defining spatial land-use distributions and the flows of goods expressed as an input-output table to provide information on the spatial and temporal characteristics of an urban region. Integrated, these models form a preliminary virtual Tokyo model when applied to Tokyo-specific databases. Given this platform, process models are applied to examine the effectiveness of using photovoltaic (PV) modules on the demand side to reduce conventional electric power generation and, thereby, also reduce carbon dioxide emissions. The results of introducing PV modules on the rooftops of buildings in Tokyo under various installation conditions are presented as a working example of the prototype. For full deployment on usable rooftop space, PV power generation could reduce carbon dioxide emissions from electric power generation by more than 12%. Future work will use the same methods as presented in this paper to examine cost, a critical determinant in the actual feasibility of PV module installation.     

基于生态需水保障的农业用水安全评价——以山东省引黄灌区为例

保障农业用水安全和生态安全是流域水资源管理的重点，针对黄河口和山东引黄灌区的用水矛盾，采用阈值分析与地统计学方法，考虑作物蒸散发和有效降雨计算山东省引黄灌区灌溉需水量，在优先保障黄河口不同等级生态需水条件下分析灌区（划分为不同调控区）可用水量的响应特征，以地理信息系统（GIS）为平台计算具有时空差异的山东省引黄灌区农业用水安全压力指数，进而评价多时空尺度下的山东省引黄灌区农业用水安全。结果表明，在平水年，保障适宜等级的生态需水后大概有33%的年份农业用水安全存在压力，保障最低等级的生态需水约有27%的农业用水面临短缺，但是大部分情况下农业用水安全压力指数都在30%之下，然而保障最高等级生态需水后，有50%以上的年份存在农业用水安全压力，这种压力无论是从出现频次还是在指数强度上都有明显增加。在空间尺度上，以打渔张、刘春家、麻湾和簸箕李等灌区为代表的调控区2、11、13、14和17的农业用水压力显著，代表年内保障最低等级的生态需水后调控区的农业用水安全压力指数超过了20%，保障适宜等级的生态需水后，大部分调控区的农业用水安全压力指数超过了20%，调控区2和13的压力指数超过了30%，保障最高等级的生态需水后大部分调控区的农业用水安全压力指数超过了60%。在引黄水量调配过程中，应该按照水文年的不同保障合理的生态水量，同时充分考虑水文气象因子的空间差异性，在不同调控区细化分配方案，平水年份保障适宜等级生态需水后农业用水短缺由55.28降低到18.25亿m³。该评价方法反映了优先保障生态需水后灌区农业水资源保障情况，并能有效降低农业和生态用水之间的矛盾，为管理部门进行"精细配水"提供依据。