Global energy demand is growing. Today, fossil fuels provide about 80% of the world's energy, and the conventional use of fossil fuels is causing carbon dioxide to accumulate in the atmosphere and affect the climate. For the US, this energy landscape poses two largely separable problems: security of supply, which is mostly about liquid hydrocarbons for transport (i.e., imported oil) and greenhouse gas emissions, which arise largely from stationary sources providing heat and power. Steve Koonin, Undersecretary for Science in the U.S. Department of Energy (DOE) and former chief scientist of BP, explores the challenges which will set the national and global agendas for the next many decades (#19391)