ABSTRACT. Water and energy are each recognized as indispensable inputs to modern economies. And, in recent years, driven by the three imperatives of security of supply, sustainability, and economic efficiency, the energy and water sectors have undergone rapid reform. However, it is when water and energy rely on each other that the most complex challenges are posed for policymakers. Despite the links and the urgency in both sectors for security of supply, in existing policy frameworks, energy and water policies are developed largely in isolation from one another-a degree of policy fragmentation that is seeing erroneous developments in both sectors. Examples of the trade-offs between energy and water security include: the proliferation of desalination plants and interbasin transfers to deal with water scarcity; extensive groundwater pumping for water supplies; firstgeneration biofuels; the proliferation of hydropower plants; decentralized water supply solutions such as rainwater tanks; and even some forms of modern irrigation techniques. Drawing on case studies from Australia, Europe, and the United States, this Special Issue attempts to develop a comprehensive understanding of the links between energy and water, to identify where better-integrated policy and management strategies and solutions are needed or available, and to understand where barriers exist to achieve that integration. In this paper we draw out some of the themes emerging from the Special Issue, and, particularly, where insights might be valuable for policymakers, practitioners, and scientists across the many relevant domains.
Key Words: energy policy; energy-water nexus; integrated planning; policy integration; water policy
INTRODUCTIONThis collection of articles grew out of a series of workshops initiated and sponsored by COST-the intergovernmental framework for European Cooperation in Science and Technology-to develop a comprehensive understanding of the links between energy and water, to identify where betterintegrated policy and management strategies and solutions are needed or available, and to understand where barriers exist to achieve that integration. The research initiative responded to the realization that while both water and energy security were attracting significant attention from scholars and practitioners alike, the interconnections between the two sectors-known as the energy-water nexus-had been underappreciated and underexplored (U.S. Department of Energy 2006, Marsh and Sharma 2007, Proust et al. 2007).