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ABSTRACT: Ecological resources constitute the basic support system for all activity on earth. These resources include products such
as air, water, minerals and crude oil and services such as carbon sequestration and pollution dissipation (Tilman et al. 2002;
Daily 1997; Costanza et al. 1997; Odum 1996). However, traditional methods in engineering and economics often fail to account
for the contribution of ecosystems despite their obvious importance. The focus of these methods tends to be on short-term
economic objectives, while long-term sustainability issues get shortchanged. Such ignorance of ecosystems is widely believed
to be one of the primary causes behind a significant and alarming deterioration of global ecological resources (WRI 2000;
WWF 2000; UNEP 2002).
To overcome the shortcomings of existing methods, and to make them ecologically more conscious, various techniques have been
developed in recent years (Holliday et al. 2002). These techniques can be broadly divided into two categories, namely preference-based
and biophysical methods. The preference-based methods use human valuation to account for ecosystem resources (AIChE 2004; Balmford et al. 2002; Bockstael et al. 2000; Costanza
et al. 1997). These methods either use a single monetary unit to readily compare economic and ecological contributions, or
use multi-criteria decision making to address trade-offs between indicators in completely different units. However, preference-based
methods do not necessitate compliance with basic biophysical laws that all systems must satisfy, and require knowledge about
the role of ecological products and services that is often inadequate or unavailable.
12/2008: pages 459-490;
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ABSTRACT: Appreciating the reliance of industrial networks on natural capital is a necessary step toward their sustainable design and operation. However, most contemporary accounting techniques, including engineering economics, life cycle assessment, and full cost accounting, fail in this regard, as they take natural capital for granted and concentrate mainly on the economic aspects and emissions. The recently developed "thermodynamic input-output analysis" (TIOA) includes the contribution of ecological goods, ecosystem services, human resources, and impact of emissions in an economic input-output model. This paper uses TIOA to determine the throughputs of natural and economic capitals along industrial supply networks. The ratios of natural to economic capitals of economic sectors reveals a hierarchical organization of the U.S. economy wherein basic infrastructure industries are at the bottom and specialized value-added industries constitute the top. These results provide novel insight into the reliance of specific industrial sectors and supply chains on natural capital and the corresponding economic throughput. Such insight is useful for understanding the implications of corporate restructuring on industrial sustainability metrics and of outsourcing of business activities on outsourcer, outsourcee, and global sustainability. These implications are discussed from the standpoints of weak and strong sustainability paradigms. The calculated ratios can also be used for hybrid thermodynamic life cycle assessment.
Environmental Science and Technology 01/2006; 39(24):9759-69. · 5.23 Impact Factor
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ABSTRACT: Industrial progress toward sustainability requires meaningful, practical, and scientifically sound metrics. Most existing metrics rely on information about material and energy inputs and emissions from the main process and selected processes in its life cycle. Such metrics often result in multiple conflicting variables, making it difficult to use them for decision making. Furthermore, sustainability metrics need to be scientifically rigorous and capable of evaluating the broader economy and ecosystem scale impacts of selected processes and products. This paper proposes a framework for evaluating the environmental sustainability of industrial processes that satisfies these needs. This framework uses exergy analysis to combine different types of material and energy streams in a thermodynamically sound manner. Exergy analysis is also combined with end-point life-cycle impact assessment methods for evaluating the impact of emissions. This results in metrics for a selected system with different levels of aggregation ranging from multiple to single dimensions. The challenge of analyzing a process at life cycle and coarser spatial scales is met by combining exergy analysis, life cycle assessment, input–output analysis, and both economic and ecological aspects. The result is a doubly nested hierarchy, which analyzes processes at multiple spatial scales of process, life cycle, economy, and ecosystem. Each scale contains another hierarchy based on the degree of aggregation of the metrics. A case study of the ammonia process illustrates the characteristics of the proposed approach. © 2004 American Institute of Chemical Engineers Environ Prog, 2004
Environmental Progress 12/2004; 23(4):302 - 314. · 0.92 Impact Factor
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ABSTRACT: Incorporation of ecological considerations in decision-making is essential for sustainable development, but is hindered by inadequate appreciation of the role of ecosystems, and lack of scientifically rigorous techniques for including their contribution. This paper develops a novel thermodynamic accounting framework for including the contribution of natural capital via thermodynamic input-output analysis. This framework is applied to the 1992 US economy comprising 91 industry sectors, resulting in delineation of the myriad ways in which sectors of the US economy rely on ecosystem products and services. The contribution of ecosystems is represented via the concept of ecological cumulative exergy consumption (ECEC), which is related to emergy analysis but avoids any of its controversial assumptions and claims. The use of thermodynamics permits representation of all kinds of inputs and outputs in consistent units, facilitating the definition of aggregate metrics. Total ECEC requirement indicates the extent to which each economic sector relies directly and indirectly on ecological inputs. The ECEC/money ratio indicates the relative monetary versus ecological throughputs in each sector, and indicates the relationship between the thermodynamic work needed to produce a product or service and the corresponding economic activity. This ratio is found to decrease along economic supply chains, indicating industries that are higher up in the economic food chain price ecosystem contribution more than the basic infrastructure industries such as mining and manufacturing. The ratio of CEC with and without inclusion of ecosystems indicates the extent to which conventional thermoeconomic analysis underestimates the contribution of ecosystems. Such ratios, made available for the first time, provide unique insight into the importance of natural capital, and are especially useful in hybrid thermodynamic life cycle analysis of industrial systems. The approach, data compiled in this work, and the resulting insight provide a more ecologically conscious tool for environmental decision-making, and has potential applications at micro as well as macro scales.
Environmental Science and Technology 10/2004; 38(18):4810-27. · 5.23 Impact Factor
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ABSTRACT: This paper develops a thermodynamic input–output (TIO) model of the 1997 United States economy that accounts for the flow of cumulative exergy in the 488-sector benchmark economic input–output model in two different ways. Industrial cumulative exergy consumption (ICEC) captures the exergy of all natural resources consumed directly and indirectly by each economic sector, while ecological cumulative exergy consumption (ECEC) also accounts for the exergy consumed in ecological systems for producing each natural resource. Information about exergy consumed in nature is obtained from the thermodynamics of biogeochemical cycles. As used in this work, ECEC is analogous to the concept of emergy, but does not rely on any of its controversial claims. The TIO model can also account for emissions from each sector and their impact and the role of labor. The use of consistent exergetic units permits the combination of various streams to define aggregate metrics that may provide insight into aspects related to the impact of economic sectors on the environment. Accounting for the contribution of natural capital by ECEC has been claimed to permit better representation of the quality of ecosystem goods and services than ICEC. The results of this work are expected to permit evaluation of these claims. If validated, this work is expected to lay the foundation for thermodynamic life cycle assessment, particularly of emerging technologies and with limited information.
Energy.
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ABSTRACT: Transitioning to more sustainable operations is widely considered to be among the premier challenges facing the chemical industry today. The motivators for such change include an increasingly tightening regulatory regime, increased consumer awareness, and inclination of investors to consider risks associated with lendings to hazardous material industries. As an effort to become “greener”, chemical industries are making conscious efforts to reduce their resource intensities or footprints. Such efforts need to be supported by models that can quantify the broad economic and environmental implications of industrial decisions. This manuscript uses the recently developed Ecologically Based Life Cycle Assessment (EcoLCA) model of the United States economy to analyze resource intensities of chemical industry sectors, comparing them with each other and with other industry sectors. The raw numbers are normalized by national flows to gain insight into possible resource vulnerabilities of industrial sectors. These numbers are also aggregated based on their mass or exergy to reduce their dimensionality and permit easier interpretation. Ecological cumulative exergy consumption (ECEC) allows consideration of a wide variety of ecosystem goods and services, human resources and emissions and their impacts on a consistent basis, and is shown to provide unique insight in addition to conventional measures based on mass and Industrial cumulative exergy consumption (ICEC). Ratios of ECEC to money indicate the relative throughputs of natural to economic capital, and are used for investigating supply chains of selected sectors and identifying likely keystone sectors. The insights obtained by juxtaposing resource intensities of chemical industry sectors amongst themselves and with those of the rest of economy are used to identify opportunities for reducing resources intensities of chemical industry sectors that could enable improvement of their environmental sustainability.
Computers & Chemical Engineering.
