Fig. 2: Fossil fuel EROI values.

a, Final- and useful-stage average EROI by fossil fuel group at the global level. b, Useful-stage EROI by end-use category by fossil fuel group at the global level. Calculations consist of a weighted average of fossil fuels used as fuels, electricity and heat. This explains the non-null value for coal products used in road propulsion, which represents coal products used in the form of electricity for road propulsion (that is, in electric vehicles).