A study by LUT University (Finland) found that 100 percent renewable power could cut water consumption up to 95 percent over conventional. Renewable power, in this case, is solar and wind, while conventional is coal, natural gas and nuclear-power generation. Renewable energy (as well as nuclear) emits no greenhouse gases that contribute to climate change, unlike coal, natural gas and other fossil fuels.
Solar PV, for instance, consumes between 2 to 5 percent of the water of coal and nuclear power plants in order to produce just 1 megawatt hours. For wind, the percentage is even lower at 0.1 to 0.14 percent. Conventional power plants consume so much water because it’s needed first for steam to spin turbines, and then, to cool that steam and return it to liquid water. A huge, overwhelming majority of the water withdrawn and consumed goes towards the cooling process. Renewable power requires plenty of water to manufacture and assemble the technology, but very little to operate in comparison to conventional power (also called thermal power).
As the study authors note:
“In this regard, renewable energy represents a viable solution as it couples almost zero greenhouse gas emissions with very low to negligible water demand for power generation.”
The study presents data from 13,863 conventional (thermal) power plants above 50 megawatts in size with a total capacity of 4,182 gigawatts. That is approximately 95.8 percent of the world’s total thermal power generation capacity. The authors’ best policy scenario, was created to evaluate water consumption for thermal and nuclear power generation between the years 2015-2050.