Introduction: Solar Energy and Human Civilization

Abstract

Solar energy has made life possible for humans and all other living things on planet Earth. Since the industrial revolution began in the nineteenth century, humanity has increasingly become dependent on a second source, solar energy-derived fossil fuels (coal, oil, natural gas). The quantity of energy from the combustion of fossil fuels surpassed that derived from biomass during the 1890s (Smil 1994). At that time humans consumed about 600 billion watts (GW) of fossil fuels per year, and by 2005 the world was consuming fossil fuels at the rate of 12 trillion watts (TW), a 20-fold increase (Smil 2006). This unprecedented increase in the availability of energy-dense fossil fuels has enabled the exponential growth of the human population and affluence for an unprecedented number of people (Hall and Klitgaard 2011).