May 30, 2024

In Washington, a dozen dams dot the Columbia River — that mighty waterway carved through the state a series of prehistoric superfloods. Between those dams and the hundreds of others that clog the rivers and tributaries that enclose the region, including California and Nevada, the Western United States accounts for most of the hydroelectric energy that the land generates from the water flows over its landscape. Washington alone captures more than a quarter of that; combined with Oregon and Idaho, the Pacific Northwest claims more than two-fifths of America’s dam-derived electricity. So when a drought hits the region, the nation takes notice.

This happened in 2023 when, according to a recent report, US hydroelectric power reached its lowest level in 22 years. While the atmospheric rivers that flowed across California provided the state with abundant energy, the Pacific Northwest endured low summer flows after a late spring heat wave caused snowpack to melt and river levels to peak earlier than normal . Although dam turbines continued to turn throughout the year – which even proves it during a drought, the country’s hydro system remains reliable — last year gave energy providers in the West a glimpse of the conditions they may have to adapt to as the world warms and seasonal weather patterns change.

While models predict climate change will plunge California and the Southwest deeper into drought, what awaits Washington and Oregon is less clear. The Pacific Northwest will warm. That much is certain. But in terms of the rain that places like Seattle and Portland are known for, things get murkier.

“When you bring in precipitation and you look at climate model results, it goes in all directions,” said Sean Turner, a water resources and hydropower engineer at Oak Ridge National Laboratory. The Evergreen and Beaver states can get drier or wetter — or both, depending on the time of year.

Nathalie Voisin, principal scientist for water-energy dynamics at the Pacific Northwest National Laboratory, said much of the latest research points to an increase in total annual hydroelectric power in the region, but, as Turner also noted, uncertainties remain . “So as a trend, we’re seeing an increase” in annual precipitation, Voisin said, “but we’re also seeing an increase in variability of very wet years and very dry years.”

Even during wet years, however, the water will not fall into a soft mist evenly distributed from New Year’s to the end of the year. Most of that, Voisin said, is expected to come from atmospheric rivers that flow overhead between fall and spring, with rivers running low in late summer as the snow and ice in the mountains surrounding the region melt earlier. melts and no longer holds water. as high as they have historically.

These are things the Bonneville Power Administration — the federal agency responsible for selling energy from the 31 federally owned dams along the Columbia and its tributaries to utilities throughout the region — has a keen eye on. In a fact sheet Outlining the agency’s plans to ensure its hydropower resources remain resilient, the administration wrote: “By the 2030s, higher average fall and winter flows, earlier peak spring runoff, and longer periods of low summer flows are very likely.” Those times of lower hydroelectric generation will coincide with periods when rising temperatures are expected to prompt people to demand more from their thermostats to stay comfortable.

Grand Coulee Dam is seen through the windows of the dam's visitor center.
Grand Coulee Dam is seen through the windows of the dam’s visitor center.
Don and Melinda Crawford / Education Images / Universal Images Group via Getty Images

Given that, if Western states like California, Washington and Oregon are to meet the 2045 100 percent clean energy goals they’ve set, their utilities will have to get creative. As it is, when hydropower fails to meet demand, methanealso known as natural gas, tends to fill the gap — even if power companies can’t say for sure that it’s their backstop.

Seattle City Light, for example, what provides electricity to more than 900,000 people over much of the Seattle area, allegedly was carbon neutral since 2005 this is largely due to an energy mix almost 90 percent hydropower – about half of which is supplied by Bonneville Power. But with its standard fleet of hydroelectric plants generating below average, Siobhan Doherty, the utility’s director of power management, said it had to acquire new energy sources to ensure it could comfortably meet customers’ needs. A fair share of that power comes from other dams in the area, but some of it is also provided by what Doherty called “unspecified” sources bought from other suppliers.

Across the West, when utilities like Seattle City Light buy energy to cover hydropower shortages, most of it comes from gas-fired peaking plants, according to Minghao Qiu, an environmental scientist at Stanford University. As a result, emissions rise. Over the 20-year period examined in a study of how droughts affect grid emissions, Qiu and his colleagues found that temporary long-term hydropower shutdowns resulted in 121 million tons of carbon emissions. Qiu also found that the plants that call for all that pollution are often located far from where the energy is needed.

While the seemingly obvious solution to this challenge is to rapidly deploy wind and solar power, Qiu found that this did not actually solve the problem.

“So what’s really happened there is an implicit market that whoever can generate the electricity at the lowest cost is going to generate first,” Qiu said. This means that sun and wind will send all the energy they can because they are by far the cheapest; hydropower then provides what it can, followed by fossil fuels such as methane to plug any holes. “So when hydro power kind of declines,” Qiu said, “the wind power and solar power are already exhausted,” which typically leaves gas plants as the remaining option.

Nevertheless, in an effort to keep its grid carbon-free in the long term, Seattle City Light recently signed agreements to buy energy from two independent solar projects, each with at least 40 megawatts of capacity, and is working on other, similar arrangements. negotiate. The fact that Bonneville Power has seen a sharp increase in requests from renewable energy developers to connect to its transmission lines suggests that other utilities in the region are exploring similar deals.

While those solar farms in a sense address the demands that hydro alone cannot meet, the West’s dams help make renewable energy work at utility scale. Regardless of the inevitable expansion and improvement of turbine and photovoltaic technology, wind and solar will always be intermittent and weather dependent. In those moments when the gusts stop blowing and the sun stops shining, something has to round out the grid. “Hydro does it better than anything,” Turner said.

Many of the dams administered by Bonneville Power are already equipped to turn up or down as demand demands, and their ability to meet these moments was perhaps never more evident than during the deadly heat dome that gripped the Pacific Northwest for one blistering week in June 2021. As streets cracked and power lines melted, the region’s homebound populations have driven demand for electricity to record levels. To keep the grid running, Bonneville Power relied on the controversial dams along the lower Snake River. The agency released a statement a month after the heat wave, revealing how critical the four lower Snake River dams were during that disaster. Sometimes they provided more than 1,000 megawatts of power, which is about the average draw in Seattle. And while there is plausible reasons for removing the damsBonneville Power said that without those resources, it would likely have to resort to rolling blackouts to ensure the system is not pushed beyond its limits.

That experience, and the many more like it sure to come, suggests that even as year-to-year declines affect the nation’s dams, the power they provide will long remain a critical component of a carbon-free future.

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