The consumptive water footprint of electricity and heat: a global assessment†
Water is essential for electricity and heat production. This study assesses the consumptive water footprint (WF) of electricity and heat generation per world region in the three main stages of the production chain, i.e. fuel supply, construction and operation. We consider electricity from power plants using coal, lignite, natural gas, oil, uranium or biomass as well as electricity from wind, solar and geothermal energy and hydropower. The global consumptive WF of electricity and heat is estimated to be 378 billion m3 per year. Wind energy (0.2–12 m3 TJe−1), solar energy through PV (6–303 m3 TJe−1) and geothermal energy (7–759 m3 TJe−1) have the smallest WFs, while biomass (50 000–500 000 m3 TJe−1) and hydropower (300–850 000 m3 TJe−1) have the largest. The WFs of electricity from fossil fuels and nuclear energy range between the extremes. The global weighted-average WF of electricity and heat is 4241 m3 TJe−1. Europe has the largest WF (22% of the total), followed by China (15%), Latin America (14%), the USA and Canada (12%), and India (9%). Hydropower (49%) and firewood (43%) dominate the global WF. Operations (global average 57%) and fuel supply (43%) contribute the most, while the WF of construction is negligible (0.02%). Electricity production contributes 90% to the total WF, and heat contributes 10%. In 2012, the global WF of electricity and heat was 1.8 times larger than that in 2000. The WF of electricity and heat from firewood increased four times, and the WF of hydropower grew by 23%. The sector's WF can be most effectively reduced by shifting to greater contributions of wind, PV and geothermal energy.