In 2010, global water withdrawals for energy production were estimated to be 583 billion cubic meters (Bm3) representing 15% of the world’s total withdrawals, of which 66 Bm3 were consumed (IEA 2012). The water sector was likewise thirsty for energy as 8% of energy consumption was used to lift, treat, and move water (WWAP 2014). Growing populations and economies threaten to intensify the energy-water nexus. By 2035, water withdrawals could increase by 20% and consumption by 85%, driven by a shift towards higher efficiency power plants with more advanced cooling systems (that reduce water withdrawals but increase consumption) and increased production of biofuel (IEA 2012). Given that 1.2 billion people currently live in areas with physical scarcity of water (UNDP 2007), there is an increasing risk of conflict between power generation, other water users and environmental considerations. Similarly, the demand for electricity by the water sector is increasing given the expanding utilization of non-traditional water sources and the move to service the world’s 2.5 billion people who lack access to water sanitation and the 748 million that lack access to safe drinking water (WHO 2014).
In light of this, the energy-water nexus was been mapped for almost 12,000 watersheds distributed across the 21-economies comprising the Asia-Pacific Economic Cooperation. Water consumption for energy production was estimated for 9 different sectors including thermoelectric and hydroelectric power; energy extraction including coal, oil, natural gas, uranium and unconventional oil/gas; and, energy processing including oil and biofuels. Conversely, the energy consumed providing water services was mapped for three sectors, drinking water, wastewater, and seawater desalination. These measures of resource use were put in context by drawing comparisons with published measures of water risk. The objective of the mapping was to quantify the energy-water nexus and its variability at the subnational level, pinpoint potential vulnerabilities, and identify opportunities for international collaboration.