Energy is an abstract concept. Formalized in the nineteenth century for the calculations of thermodynamics, it is a largely metaphorical term in everyday usage, where it can represent everything from personal vitality to national wealth. The term came into wide use with the increased extraction and exploitation of hydrocarbon fuels, loosely with the mining of coal in the nineteenth century and extraction of oil and natural gas in the twentieth. As technological civilization grew and became more energy intensive (and energy efficient) through that period, each shift or disruption in fuel production has prompted anxiety about the nature of the dependence, from Jevons writing about coal production in the nineteenth century, to the Limits to Growth report in the 1970s and the most recent Roadmap 2050 for “a prosperous, low-carbon Europe.”1 As Luis Fernández-Galiano observes, energy accounting quickly becomes “the philosopher’s stone that would make it possible to reconcile technology and nature, economics and ecology.”2