A recent Duke University study suggests that the ongoing transition from coal to renewables and natural gas in the U. S. electricity industry is drastically cutting the sector’s water consumption. Avner Vengosh, Professor, Geochemistry and Water Quality, Duke’s Nicholas School of the Environment, says that while most attention has been concentrated on the air quality and climate advantages of shifting away from coal, the new research shows that this transition to natural gas, and even more so, to renewable sources of energy, has helped save billions of gallons of water. These savings in both water withdrawal and water consumption have been accomplished in spite of the intensification of water usage for applications like fracking and shale gas production.
Andrew Kondash, Postdoctoral Researcher, Duke, who headed the study for his doctoral dissertation under Vengosh, says that for every megawatt of electricity generated with natural gas instead of coal, water withdrawn from local rivers and groundwater is cut by 10,500 gallons, equivalent of a 100-day water supply for a standard American household, while water consumption is reduced by 260 gallons per megawatt. With these rates of reduction, if shale gas progressively continues to replace coal over the next decade, by the year 2030, nearly 483 billion cubic meters of water will be saved in a year, as predicted by the Duke study. Although the magnitude of water consumption for coal mining and fracking is similar, cooling systems in natural gas power plants utilize much less water than in coal plants, which can quickly add up to sizable savings, since 40% of all water consumption in the United States is directed towards thermoelectric plants.
Vengosh says that switching to wind or solar energy could eliminate most of the water consumption and water withdrawals for electricity production in the U.S. The study indicates that the water intensity of these renewable energy sources, as calculated by water consumption per kilowatt of electricity, is only 1 to 2% of the water intensity of coal or natural gas.