Economic growth is bound to the consumption of energy (Berndt 1983; Metz et al. 2007). In the last three decades, each 1 % increase in global gross domestic product (GDP) was on average associated with a rise of 0.7 % in primary energy demand (International Energy Agency 2009). Forecasts of the U.S. Energy Information Administration anticipate the continuation of this trend with marginally decreasing intensity. In 2035, the primary energy demand is expected to rise by 0.56 % per marginal growth in GDP resulting in a total demand of 738.7 quadrillion Btu (U.S. Energy Information Administration 2010).