A model of US water systems foresees a big drop in hydropower generation by 2050 as the climate gets drier and river flow decreases, while electricity demand is set to increase.
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| Glen Canyon Dam on the Colorado river in Arizona (Credit: iStockphoto / Getty Images) |
Hydropower generation in the western US may fall by as much as 20 per cent by 2050 due to climate warming, even as electricity demand increases, a study has predicted.
Snowy peaks are called the “water towers” of the western US because their meltwater feeds its rivers through the hot summer. But as temperatures rise, leading to less snow and more evaporation, stream flow will decrease across most drainage basins.
That could result in up to 20 per cent less electricity generation by dams annually and up to 30 per cent less in the summertime, according to a model developed by David Yates at the National Center for Atmospheric Research in Boulder, Colorado, and his colleagues.
At the same time, water-related electricity use will increase by up to 4 per cent each year and 6 per cent in the summer, largely because farmers will have to pump more groundwater for irrigation. That is in addition to the higher summer electricity demand for air conditioning that is already expected.
“We see the whole Western Interconnect [power grid] on the electricity side responding to the push or the tension that the water sector will place upon it,” says Yates.
Currently, the reservoirs behind the Glen Canyon and Hoover dams are barely a third full because cities and farms continue to extract too much water from the Colorado river, a problem compounded by the worst megadrought in 1200 years. A snowy winter in 2022-23 and an agreement between California, Arizona and Nevada to reduce water use staved off “dead pool” levels – when water can’t flow downstream from dams – but these factors aren’t enough to address long-term warming.
The study shows that the shift away from fossil fuels planned by several western states could be more difficult than anticipated, since the traditional stopgap for falls in hydropower or surges in demand is to use natural gas, says Jordan Kern at North Carolina State University.
“You have to plan around not just this changing climate, which could alter your water availability, but also electricity demand, while also using [solar and wind] power plants that are in some ways less predictable,” he says.
Such strains on the system are already becoming more relevant. A report by the regulatory authority that oversees the North American power grid recently concluded that the western US will face an elevated risk of power shortages during heatwaves or storms as soon as this year.”
Journal reference:
Earth’s Future DOI: 10.1029/2022EF003220
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