Energy production depends on water. It is used in power generation, primarily for cooling thermal power plants; in the extraction, transport and processing of fuels; and, increasingly, in irrigation to grow biomass feedstock crops. Energy is also vital to providing freshwater, needed to power systems that collect, transport, distribute and treat it. Each resource faces rising demands and constraints in many regions as a consequence of economic and population growth and climate change, which will amplify their vulnerability to one another.
For the energy sector, constraints on water can challenge the reliability of existing operations as well as the physical, economic and environmental viability of future projects. Equally important to water-related risks confronted by the energy sector, the use of water for energy production can impact freshwater resources, affecting both their availability (the amount downstream) and quality (their physical and chemical properties). And the dependence of water services on the availability of energy will impact the ability to provide clean drinking water and sanitation services.
The IEA first assessed the water-energy nexus in the World Energy Outlook 2012, dedicating a chapter to analysis of the water-for-energy relationship, reviewing water requirements for different energy sources (primary energy production and electricity generation) and estimating total freshwater needs by scenario, energy source and region. In subsequent years, the WEO has addressed various facets of the nexus: the WEO Special Report Redrawing the Energy-Climate Map in 2013 looked at energy infrastructure and climate resiliency; while the World Energy Outlook 2015 assessed the impact of water scarcity on coal-fired power plants in India and China as well as water requirements of unconventional gas production.
The World Energy Outlook 2016 once again has a dedicated chapter covering the energy-water nexus and looks at how the complex interdependencies between these two resources will deepen in the next decades (see the methodology). This analysis updates the work done in 2012 and assesses current and future freshwater requirements for energy production, highlighting potential vulnerabilities and key stress points. In addition, for the first time, the World Energy Outlook looks at the energy-for-water relationship, analysing the energy requirements for different processes in the water sector, including water supply, water distribution, wastewater treatment and desalination. Key findings were released at the CDP Global Water Forum at COP22 on 15 November, 2016.