Long-Term Estimates of the Energy-Return-on-Investment (EROI) of Coal, Oil, and Gas Global Productions

Résumé En

We use a price-based methodology to assess the global energy-return-on-investment (EROI) of coal, oil, and gas,fromthe beginning of their reported production (respectively 1800, 1860, and 1890) to 2012. It appears that theEROI of global oil and gas productions reached their maximumvalues in the 1930s–40s, respectively around 50:1and 150:1, and have declined subsequently. Furthermore, we suggest that the EROI of global coal production hasnot yet reached its maximumvalue. Based on the originalwork of Dale et al. (2011), we then present a new theoreticaldynamic expression of the EROI.Modifications of the originalmodelwere needed in order to performcalibrationson each of our price-based historical estimates of coal, oil, and gas global EROI. Theoretical modelsreplicate the fact that maximum EROIs of global oil and gas productions have both already been reached whilethis is not the case for coal. In a prospective exercise, the models show the pace of the expected EROIs decreasefor oil and gas in the coming century. Regarding coal, models are helpful to estimate the value and date of theEROI peak, which will most likely occur between 2025 and 2045, around a value of 95(±15):1.