The Energy ChallengeThe last 10 years have witnessed dramatic changes in global civilization, including the impact of technological innovation on the level and quality of life and rapidly expanding middle class populations in developing nations. While these changes yield a broad range of positive outcomes, they also lead to the challenge of meeting the increasing energy requirements of the global society in a sustainable and environmentally-responsible manner. Indeed, energy and consequences of energy usage is one of the most important, and perhaps the most important, challenge facing humanity.The magnitude of the challenge can be seen in the estimates of future energy requirements. The US Department of Energy predicts that global energy requirements will increase over the 2008 values by 50% by the year 2035, Fig. 1. 1 The supply of this amount of energy will require drastic changes in the major energy sources, and increased attention to the environmental impacts.