Climate change will cause existing hydroelectric dams to generate more power in the Pacific Northwest and around the lower 48 states in the coming decades. That’s according to projections from an August study by the U.S. Department of Energy’s Richland-based Pacific Northwest National Laboratory.
The study looked at how the changing climate will impact weather, and then how that in turn will impact hydroelectric generation between 2020 and 2059 — a period when regional electricity demand is projected to grow.
The findings also come at a time when dams are caught between their important role in meeting Washington’s 2045 fossil fuel-free grid mandate and ever-increasing scrutiny because they harm Native nations and salmon.
Changing climate
Dan Broman, an applied hydro-climatologist at Pacific Northwest National Laboratory, led the complex, multiyear study. It was completed using computer climate modeling, an approach he described in layperson’s terms as turning a “crank to produce the numbers that are in the study.”
The research used worst-case-scenario climate change projection data. But even those projections, Broman said, line up with more moderate ones until the last decade of the study period.
Although the research is forward-looking, climate change’s footprint is already visible. Around the time he was midway through his doctoral program in 2015, Broman said he started to notice things changing — and those shifts soon started to alter the work he was doing.
“A lot of the work that I did in graduate school, and then just after, used statistics in some way to say, ‘The past can inform the future; these relationships that we have (come to understand) to relate these water quantities — whether it’s snow or stream flow or precipitation — we can use these to understand what might happen next season or next year or over the next 10 years,’” he said.
“And we started seeing like, ‘Oh, they’re just not really working the way that they used to work,’” Broman continued. “Things were kind of falling apart, and that was really eye-opening to me.”
The model the Pacific Northwest National Laboratory team used projects that by 2050, the Pacific Northwest will have hotter temperatures, drier summers and more precipitation. That precipitation will be increasingly concentrated outside of summer in the spring, fall and winter. Compounding the change, an increasing percentage of it will also fall as rain as opposed to snow as our climate warms. (Those projections are in line with what the Washington Department of Ecology’s Office of the Columbia River found in its most recent long-term water supply and demand forecast.)
In sum, that means more of the water that comes down the Columbia will come outside of summer.
Hydropower
Those changes mean more of the water that comes down the river can be used for hydroelectric generation.
Dams are required in spring and in parts of summer to allow a larger-than-usual percentage of the river to go down spillways as opposed to through their power-generating turbines.
That’s because salmon offspring generally head to sea around those times, and turbines are known to kill about 10-15 percent of fish that pass through them. Newer turbines lower that rate.
Accordingly, more water in the winter means more water flowing through turbines, and that means more power.
More specifically, the study projected that between 2020 and 2039 hydroelectric in the Pacific Northwest will change — somewhere in the range of a decline of 3 percent to an increase of 17 percent. And it will change — between a decline of 6 percent and an increase of 27 percent — in the two decades following that. Changes varied by region of the contiguous U.S.
Of the nearly 500 dams in the Columbia River Basin, more than half produce hydroelectricity, 29 are major and only nine are federally operated. The others are run by local public utility districts and other parties. (The federal projects are larger, though: Despite making up six of the 11 projects on the mainstem Columbia River, for instance, federal operated dams generate nearly 90 percent of average yearly power produced on the river.)
Broman said the study was carried out to fulfill federal obligations under the SECURE Water Act and expanded to provide a more thorough picture of how climate change will impact hydropower around the lower 48 states.
The U.S. Army Corps of Engineers, which runs five of the federal dams on the mainstem Columbia, said in a statement that while climate change modeling “still has much uncertainty,” it shows trends toward more extreme water conditions, for which the agency is preparing.
“However, the degree to which the energy production will be impacted is unknown at this time,” Corps spokeswoman Kerry Solan added.
Pacific Northwest National Laboratory’s results are consistent with a 2020 report by BPA, the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation.
“Projected increases in regulated streamflow during the winter and early spring increase the potential for hydropower generation for both the federal and the U.S. systems,” that report concluded.
The change does come with significant downsides, according to that report, which found the lack of rain during the summer stands to hurt summer power generation, fish, agriculture and the river’s navigability to ships.
While hydroelectric generation capability will decrease during the summer, the 2020 report noted demand during that time would increase due to hotter temperatures and the resulting need for air conditioning. And, compounding the challenges, another BPA report last month found that demand for power is projected to greatly increase across the region because of industries like data centers.
Broman of Pacific Northwest National Laboratory said his team is now working with partners at BPA and other agencies to complete the next national assessment.
