SoylentNews is people
SoylentNews
Replacing Coal with Gas or Renewables Saves Billions of Gallons of Water:
"While most attention has been focused on the climate and air quality benefits of switching from coal, this new study shows that the transition to natural gas—and even more so, to renewable energy sources—has resulted in saving billions of gallons of water," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment.
[...] "For every megawatt of electricity produced using natural gas instead of coal, the amount of water withdrawn from local rivers and groundwater is reduced by 10,500 gallons, the equivalent of a 100-day water supply for a typical American household," said Andrew Kondash, a postdoctoral researcher at Duke, who led the study as part of his doctoral dissertation under Vengosh.
[...] If all coal-fired power plants are converted to natural gas, the annual water savings will reach 12,250 billion gallons—that's 260% of current annual U.S. industrial water use.
Although the magnitude of water use for coal mining and fracking is similar, cooling systems in natural gas power plants use much less water in general than those in coal plants. That can quickly add up to substantial savings, since 40% of all water use in the United States currently goes to cooling thermoelectric plants, Vengosh noted.
[...] Even further savings could be realized by switching to solar or wind energy. The new study shows that the water intensity of these renewable energy sources, as measured by water use per kilowatt of electricity, is only 1% to 2% of coal or natural gas's water intensity.
"Switching to solar or wind energy would eliminate much of the water withdrawals and water consumption for electricity generation in the U.S.," Vengosh said.
Quantification of the water-use reduction associated with the transition from coal to natural gas in the U.S. electricity sector, Environmental Research Letters (DOI: 10.1088/1748-9326/ab4d71)
(Score: 4, Informative) by Anonymous Coward on Wednesday October 23 2019, @08:53AM
"Consumed" for cooling ... sad, but true. Journalists can't even think properly before writing BS sometimes, even when they have proper sources. But I guess they write sometimes, not think. You can see that immediately with "per megawatt electricity produced"... No such thing. Megawatt is unit of power, not energy. You don't produce "megawatts" - you produce Megawatt-hours.
Now, 10,000 gal. of water is about 40,000 liters which has heat capacity of 4.1J/C/g. That's 40m3, so basically fits in one 20ft. cargo container. So specific heat capacity of 40k liters is 4.1 * 40e6 = 160e6J/C. 1 MWh is 1e6*3.6e3=3.6e9J... or 3.6e9 / 160e6 = 22.5C. And since these thermal plants are running is 30% thermal efficiency, this looks like 1MWh-electric at your socket causes 40 tonnes of water to be evaporated at the cooling towers, in dust control and similar.
So, it's *consumed* would be right.
Gas is more like 60% efficient, which by definition must use less water per MWh.