Energy is the only universal currency, it is necessary for getting anything done. The conversion of energy on Earth ranges from terra-forming forces of plate tectonics to cumulative erosive effects of raindrops. Life on Earth depends on the photosynthetic conversion of solar energy into plant biomass. Humans have come to rely on many more energy flows -- ranging from fossil fuels to photovoltaic generation of electricity -- for their civilized existence. In this monumental history, Vaclav Smil ...