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

Summary 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 the EROI of global oil and gas productions reached their maximumvalues in the 1930s–40s, respectively around 50:1 and 150:1, and have declined subsequently. Furthermore, we suggest that the EROI of global coal production has not yet reached its maximumvalue. Based on the originalwork of Dale et al. (2011), we then present a new theoretical dynamic expression of the EROI.Modifications of the originalmodelwere needed in order to performcalibrations on each of our price-based historical estimates of coal, oil, and gas global EROI. Theoretical models replicate the fact that maximum EROIs of global oil and gas productions have both already been reached while this is not the case for coal. In a prospective exercise, the models show the pace of the expected EROIs decrease for oil and gas in the coming century. Regarding coal, models are helpful to estimate the value and date of the EROI peak, which will most likely occur between 2025 and 2045, around a value of 95(±15):1.