The Pacific Northwest could see a slight increase in hydroelectric power generation over the next 15 years, but climate change could impact how and when that energy might be used, according to a new study.

The Pacific Northwest National Laboratory found Electricity generation from hydropower, a renewable energy source that uses the power of flowing water to generate electricity, could increase by 5% across the United States by 2039 and 10% by 2059.

Only in the southwest is there likely to be an average decline in hydropower due to drought during this period.

Oregon and Washington saw a 20% decline in production in 2023 compared to 2021the lowest level in two decades.

But to look even further into the future, federal researchers collected data from more than 1,400 hydroelectric plants and compared it with data showing how rising global temperatures might affect water flow and volume. The PNNL data showed that as the planet continues to warm, increases in seasonal precipitation slightly boost hydroelectric generation.

But the projected increases could be thwarted by the uncertainty of climate change and other extreme weather events. Researchers say that by providing nationwide data, dam operators and utilities can better plan when and how to use hydropower.

“We know the climate is changing, and we know that will impact how much water will be available to generate hydropower,” said Daniel Broman, a hydroclimatologist at the Pacific Northwest National Laboratory and lead author of the study, in a statement. “Our research provides a unified view across the country, so even if water and energy planners are only looking ahead regionally, our data can provide a broader outlook.”

As temperatures continue to rise due to the burning of fossil fuels, researchers investigated how climate change might affect a renewable energy source that has been used for decades to power homes, as well as provide flood prevention and adequate water supplies. It is a Energy source whose production could increase while the country abandons its dependence on fossil fuels to reduce greenhouse gas emissions.

In the Pacific Northwest, hydropower provides 60 percent of the region’s energy, according to the study.

In Oregon, Hydropower accounted for nearly 40% of the state’s electricity mix in 2021because the Cascades provide abundant meltwater that flows into nearby rivers.

However, higher temperatures could alter the amount of precipitation and snowmelt in the region and create situations where utilities need to adjust their hydropower timing, says Nathalie Voisin, PNNL’s chief researcher for regional hydropower dynamics.

“The fact that temperatures will be higher means that water will melt sooner instead of being stored in the snowpack,” she said.

Climate change could lead to more rainfall in the winter and spring months, which would encourage water flow and increase the amount of energy that can be generated through hydropower, Voisin said.

But during the summer and fall months, higher temperatures are expected to cause snow cover in the mountains to thin, meaning less water will be available for hydropower, she said.

These changes could pose a challenge for water managers and utilities as they face growing demand for more renewable energy production, Voisin said.

“Hydropower cannot produce the electricity that is needed,” Voison said, noting that drought could affect the amount of renewable energy that can be produced by hydropower, especially as a constant “baseload” resource. But because of hydropower’s flexibility, it can “ramp up” production when renewable energy sources like wind and solar are not producing enough energy.

The use of hydropower as battery storage or reserve energy is also crucial, said Voisin. already underway in the northwest to use what’s known as “pumped storage” to make hydropower more flexible. This helps utilities better balance variable sources such as wind and solar, she said.

Overall, Voisin says hydropower is still a reliable source of renewable energy, especially when combined with other renewable energy sources. However, she says the use of hydropower may require better coordination in the future and that electricity grids may need to be interconnected regionally to meet demand.

“Right now, these utilities are looking at what they need to build or how they need to work with other regions,” she said. “…Instead of building everything locally, there’s also a lot of regional coordination, and so utilities are currently trying to figure out what technology mix they need or what coordination they need to be able to meet that electricity demand.”