IREES colloquium: Exergy as a measure for environmental burden? A conceptual exploration| Professor Martin de Wit, Stellenbosch University.

Speaker | Professor Martin de Wit, Stellenbosch University.

Title |Exergy as a measure for environmental burden? A conceptual exploration

Summary

Problem | Several recent global assessments point to a rapidly deteriorating global environment with potentially dire consequences for the sustainability of life on the planet. Legitimate questions are raised on the adequacy of existing environmental management frameworks, models, tools, and policies to achieve global sustainability. One aspect of this problem is how environmental burden is measured. In mainstream approaches to environmental management measurements, a consistent and recurring problem is that environmental and ecological indicators do not correspond well with physical, chemical, and biological material realities.

Purpose:

A widespread integration of the laws of thermodynamics into the field of environmental management and sustainability is needed. The purpose of the research is to contribute towards a greater acceptance of exergy analysis, as a measure of thermodynamic potential, in the field of environmental management and sustainability.

Method and approach:

The method followed is an interdisciplinary literature review on exergy as a viable measure for environmental burden. The approach is to construct a logical and coherent non-technical argument to enhance understanding and acceptance of proof of concept.

Key results and its relevance:

Exergy concepts and methods, databases and tools are well developed on energy and material use and waste emissions. Exergy analysis is implemented far beyond the initial technical analysis focussed on identifying inefficiencies in industrial processes, and now also  used for environmental, thermo-economic, and sustainability assessments and models, as well as in the analysis of natural ecosystems. The concept of exergy is further well accepted as a measure of environmental burden, but with some notable exceptions and limitations such as the harmfulness of waste emissions. Challenges remain in the calculation of reference environments, especially the chemical exergy of living systems, in the calculation of embodied exergy in waste emissions and the exergy of ecosystems, and the integration with human values and preferences in decision making. Some components for an improved conceptual framework are highlighted.

Conclusions:

Exergy as a measure for environmental burden carries the advantage that thermodynamic second law inefficiencies and irreversible environmental effects can be included in environmental and sustainability assessments on a scientific basis. The concept can be used to extend on certain existing environmental management approaches and tools, notably environmental indicators and life-cycle analysis. Some remaining challenges and limitations affecting the efficacy of environmental management and sustainability are highlighted. An improved conceptual framework for exergy as measure for environmental burden is envisaged for future work.