Energy, water and food systems are closely interlinked in the Energy-Water-Food Nexus. Water is of paramount importance for the energy sector. For example, thermal power plants require water for cooling, whether they use nuclear, fossil or biofuels. Feedstock production for biofuels may depend on water for irrigation. On the other hand, energy is necessary for pumping of ground and surface water, for water treatment as well as for transport and distribution of water to end-users. Waste water is often returned to the environment after energy requiring waste water management. Most modern crop production is inconceivable without external inputs of water. For example, agriculture and livestock farming consumes energy for land preparation and tillage. Add to this the use of energy-intensive products like fertilizers, pesticides, and animal feed. The complexity in the Energy-Water-Food Nexus is not at least apparent in transboundary water systems. For example, the building of a new hydropower plant in an upstream country will have a number of consequences for the downstream countries in the competition for the same water resources for e.g. thermal power production and for agriculture as well as for fishing. The demand for resources is increasing due to both economic and population growth, more competition and – in some places – scarcity which may affect the security of supply across the three sectors. Climate change is likely to increase this pressure. Even so, today most of the policy and administrative decisions within each of the three sectors are made by separate institutions with no or little emphasis on local, national or regional nexus coordination. DTU International Energy Report 2016 brings up these issues and analyses challenges and opportunities for wider introduction of the nexus concept from local to global scale in order to enhance the security and sustainability in the Energy-Water-Food Nexus.