PARENT SESSION
Oral Session #2: Thermodynamics and Complexity. Presiding: T. Allen.
Monday, August 6, 2001. 8:00 AM to 11:45 AM. Madison Ballroom D.
New perspective on the exergy of solar radiation vis-a-vis ecosystems.
Fraser, Roydon1, Kay, James1, 1
ABSTRACT- The objective of this paper is to quantify the exergy of solar radiation received by ecosystems, and in the process apparently resolve the exergy of solar radiation controversy. Ecosystems maintain order by utilizing the exergy content of solar radiation that exists due to the sustained temperature gradient between the sun and the ecosystem's environment. That is, ecosystems exist by controlling the method and rate of solar radiation exergy destruction. In effect, ecosystems are simply complex solar collectors. This paper builds on the investigation strategy discussed in the paper entitled, "Viewing Ecological Systems as Black Box Thermodynamic Systems: The Importance of the Exergy Viewpoint." In particular, quantifying the exergy of solar radiation is the first step in performing a black box thermodynamic characterization of an ecosystem. A major controversy exists, however, in the engineering and physics communities about how to correctly quantify solar exergy. This controversy is largely resolved by the introduction of four fundamental classes of exergy: intrinsic exergy, transport exergy, restricted exergy, and accessible exergy. Furthermore, the new perspective, offered by this exergy classification, reveals that the definition of system environment, currently used in exergy discussions, is unsatisfactory. We therefore also present clarifications and refinements to the definition of environment, and consequently, dead state. This work is the first step in quantitatively characterizing ecosystems using the black box thermodynamics approach.
KEY WORDS: ecosystem, complexity, thermodynamics, exergy