This paper attempts to address two issues. First, is how to objectively measure carbon dioxide emissions from the generation of electricity that uses predominantly coal. Second, is how to incorporate these ‘environmental’ variables into an efficiency model. Using a technique called Data Enveloping Analysis (DEA) a non-parametric piecewise surface (or frontier) over the data is constructed, so as to be able to calculate technical efficiencies (which I call environmental efficiency) relative to this surface. These ‘environmental efficiency’ measures are analyzed. The technique utilized in this study may be extended to calculate each agent’s allocative and scale efficiencies in order to calculate a shadow price for carbon dioxide emissions and to formulate a preliminary permits scheme for carbon dioxide emissions generated by electric utilities.