Grantee Research Project Results
Reconciling Consumption and Conservation: Using an Exergy-Based Measure of Consumption To Strengthen the Conceptual Framework of Industrial EcologyEPA Grant Number: U914950
Title: Reconciling Consumption and Conservation: Using an Exergy-Based Measure of Consumption To Strengthen the Conceptual Framework of Industrial Ecology
Investigators: Connelly, Lloyd G.
Institution: University of California - Berkeley
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 1996 through October 8, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Mechanical Engineering , Academic Fellowships , Safer Chemicals
The objective of this research project is to demonstrate that the form and significance of the ecosystem analogy at the core of industrial ecology (IE) may be greatly strengthened by using the property exergy—a measure of accessible work potential—to define resource consumption as exergy removal. Efforts to reduce resource depletion have intensified in recent years with the emergence of IE. Proponents of IE seek to use the evolution of biological ecosystems as a model for reducing resource depletion in industrial systems. Although the literature on IE offers an important set of objectives and organizing principles for reforming industrial activities, as a field of study, IE remains unexplored and ambiguous on several levels. One "core" philosophical deficiency is the lack of a physical interpretation of resource consumption and associated ambiguity about the roles and limitations of resource conservation strategies such as waste cascading and recycling.
An exergy-based definition of consumption provides a basis for developing an exergy-based definition of resource cycling—the cycling of material exergy—that differentiates among full and partial cycling, recirculation, and cascading of consumed resources. Defining consumption as exergy removal also provides a basis for developing a thermodynamic interpretation of ecosystem evolution as a process of allowing resource consumption to occur with decreasing levels of resource depletion (i.e., a process of "delinking" consumption from depletion). I express the resource depletion rate as a product of consumption rate and the depletion number (Dp), a nondimensional indicator of depletion per unit consumption that provides one measure of ecosystem progress on an evolutionary scale. I then use the depletion number as a focal point for developing an analytical framework that characterizes the highly interdependent roles of cascading, cycling, efficiency gains, and renewed exergy use in delinking resource consumption from resource depletion. To depict resource flows and quality variations in resource cycling networks, I introduce an exergy-based "flow quality diagram." I then use this diagram and the associated analytical framework to analyze strategies for depletion avoidance in idealized aluminum beverage containers and benzene cycling networks.