Hydropower’s Future Is Clouded by Droughts, Floods and Climate Change – It’s Also Essential to the U.S. Electric Grid

Climate Change Affects Hydropower in Different Ways in Different Regions
Globally, drought has already decreased hydropower generation. How climate change affects hydropower in the U.S. going forward will depend in large part on each plants’ location.

In areas where melting snow affects the river flow, hydropower potential is expected to increase in winter, when more snow falls as rain, but then decrease in summer when less snowpack is left to become meltwater. This pattern is expected to occur in much of the western U.S., along with worsening multiyear droughts that could decrease some hydropower production, depending on the how much storage capacity the reservoir has.

The Northeast has a different challenge. There, extreme precipitation that can cause flooding is expected to increase. More rain can increase power generation potential, and there are discussions about retrofitting more existing dams to produce hydropower. But since many dams there are also used for flood control, the opportunity to produce extra energy from that increasing rainfall could be lost if water is released through an overflow channel.

In the southern U.S., decreasing precipitation and intensified drought are expected, which will likely result in decreased hydropower production.

Some Grid Operators Face Bigger Challenges
The effect these changes have on the nation’s power grid will depend on how each part of the grid is managed.

Agencies known as balancing authorities manage their region’s electricity supply and demand in real time.

The largest balancing authority in terms of hydroelectric generation is the Bonneville Power Administration in the Northwest. It coordinates around 83,000 megawatt-hours of electricity annually across 59 dams, primarily in Washington, Oregon and Idaho. The Grand Coulee Dam complex alone can produce enough power for 1.8 million homes.

Much of this area shares a similar climate and will experience climate change in much the same way in the future. That means that a regional drought or snowless year could hit many of the Bonneville Power Administration’s hydropower producers at the same time. Researchers have found that this region’s climate impacts on hydropower present both a risk and opportunity for grid operators by increasing summer management challenges but also lowering winter electricity shortfalls.

In the Midwest, it’s a different story. The Midcontinent Independent System Operator, or MISO, has 176 hydropower plants across an area 50 percent larger than that of Bonneville, from northern Minnesota to Louisiana.

Since its hydropower plants are more likely to experience different climates and regional effects at different times, MISO and similarly broad operators have the capability to balance out hydropower deficits in one area with generation in other areas.

Understanding these regional climate effects is increasingly essential for power supply planning and protecting grid security as balancing authorities work together to keep the lights on.

More Change Is Coming
Climate change is not the only factor that will affect hydropower’s future. Competing demands already influence whether water is allocated for electricity generation or other uses such as irrigation and drinking.

Laws and water allocation also shift over time and change how water is managed through reservoirs, affecting hydroelectricity. The increase in renewable energy and the potential to use some dams and reservoirs for energy storage might also change the equation.

The importance of hydropower across the U.S. power grid means most dams are likely here to stay, but climate change will change how these plants are used and managed.

Caitlin Grady is Assistant Professor of Civil and Environmental Engineering and Research Associate in the Rock Ethics Institute, Penn State. This article is published courtesy of The Conversation.This article was updated May 18, 2022, to clarify that Bonneville Power Administration coordinates power from 59 dams.