Resumen
Most estimates of energy-return-on-investment (EROI) are ?static?. They determine the amount of energy produced by a particular energy technology at a particular location at a particular time. Some ?dynamic? estimates are also made that track the changes in EROI of a particular resource over time. Such approaches are ?bottom-up?. This paper presents a conceptual framework for a ?top-down? dynamic function for the EROI of an energy resource. This function is constructed from fundamental theoretical considerations of energy technology development and resource depletion. Some empirical evidence is given as corroboration of the shape of the function components.