The two major challenges facing humanity today are related. Despite technological progress, society is incapable of providing the world’s population with two basic needs: energy and water. By 2050, the global population is expected to level off at between 9 and 10 billion people -- 50 percent more of us than there are today. Population growth is pushing food production systems to new limits. Food production, estimated by the FAO to double by 2050, is in turn increasingly water and energy dependent, and in competition with energy for transportation and power. Fighting climate change may further increase the tension between the two and force trade-offs over water use by an increasingly decarbonized energy system. This session brings together experts from the United States, United Kingdom, Germany, and European Union to examine the growing inter-linkage between energy and water systems. Can biofuels or biomass see us through, or do they represent a growing strain on water systems? What is the hidden impact of cooling water needs for "green technologies" such as concentrated solar power, nuclear energy, and carbon capture and storage? The latest insights into innovative, multidisciplinary approaches to solving the energy and water nexus will underpin the discussion.