Grantee Research Project Results
Reconciling Consumption and Conservation: Using an Exergy-Based Measure of Consumption To Strengthen the Conceptual Framework of Industrial Ecology
EPA Grant Number: U914950Title: 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
Objective:
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.
Approach:
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.