A thermodynamic basis for evaluating environmental policy trade-offs

Abstract

This paper introduces a novel thermodynamic measure of chemical change in the environment called pollution potential, which is defined as the change in exergy of mixing per mole of chemical species in the environment that may be attributed to pollutant releases – equivalent to the ideal exergy per mole required to remove a pollutant from the environment. Because all chemical pollutants may be measured in terms of pollution potential, the methodology described may provide a scientific basis for cross-comparison of disparate environmental impacts such as global warming potential (GWP) and ozone depletion potential (ODP) in a single measure. As an illustrative example, steady-state pollution potentials are calculated for several CFC replacements and a strong correlation between pollution potential and GWP is found for hydrofluorocarbons (HFCs). Although ozone depletion is found to be a significant factor in the pollution potential of CFC-11, for hydrochlorofluorocarbons (HCFCs) the contribution of ozone effects to total pollution potential is minimal. These findings suggest that policies that favor marginal reductions in ODP without regard for other environmental effects (e.g. climate change) may have unintended and detrimental consequences.