Extended-exergy based energy return on investment method and its application to shale gas extraction in China

Abstract

Energy Return on Investment (EROI) has become a policy analysis tool related to sustainability. However, most EROI studies adopt the standard EROI method, which has two inherent defects. First, standard EROI leaves out energy quality. Second, input factors such as labor, auxiliary services and environmental factors are not considered. Therefore, this paper introduces exergy into the EROI calculation and establishes a new extended exergy-based EROI (ExEROI). ExEROI treats “available energy” as energy quality; with the idea of embodied flows, ExEROI quantifies all the five input factors of the EROI analysis framework. Shale gas exploitation in the Sichuan Basin is used as an example in the case study. The ExEROI result is 9.68, which is much lower than the standard EROI result of 82.95. This is due to the inclusion of more input factors and the fact that the input factors are measured by exergy. Specifically, the auxiliary service input factor accounts for 77.10% of the total inputs, and such inputs are ignored by the standard EROI method. ExEROI makes up for the shortcomings of standard EROI and avoids the possible misinformation caused by standard EROI. ExEROI has the potential for use as an integral aspect of energy resource exploitation evaluations.