Climate-fed heat waves will disrupt western hydropower

CLIMATEWIRE | When California suffers from heat waves, it relies heavily on hydropower from the Northwest Pacific to maintain lighting.

But this hydropower may not always be available when it is most needed, as climate change is displacing the soil on which Western dams are located. Higher temperatures mean that snowmelt occurs earlier in the year and leaves less water to produce electricity in the depths of summer. The result is an increased risk of power outages during extreme heat waves as a result of lower water availability, according to a report released this week by North American Electric Reliability Corp. (NERC).

The report highlights the paradox of power grid management in the region in a warming world: as energy demand rises with temperatures, there may be fewer water sources of energy supply, increasing the need for fossil fuels.

“Overall, hydropower is a low-carbon source of electricity that is needed to tackle climate change,” said Steve Klemmer, director of energy research at the Union of Concerned Scientists. “At the same time, it is an electrical resource affected by climate change.

According to NERC, the biggest threat to the West is a heat wave like the one that boils cities from Seattle to Tucson in 2020 (Energy conductor, May 19). Higher temperatures are straining the grid, as growing demand means there is less backup power to supply from one part of the region to another. The risk of power outages is particularly acute in the early evening hours, when solar power begins to decline, but demand for electricity remains high.

Against this background, hydroelectric energy is becoming particularly important. Soon study published in the journal The future of the Earth found that the availability of water and summer air temperatures are probably the biggest determinants of Western electricity prices in the coming decades.

“If we have heat waves that increase demand, then the loss of hydromassage energy becomes really important,” said Adrien Marshall, a computational hydrologist at the Colorado Mining School.

The challenges vary in different parts of the West, she said. In general, scientists expect temperate regions of the world to become wetter and drier regions drier with rising temperatures.

The problem in the northwest is seasonal. Many dams in the region are subject to regulations that require them to manage water levels to protect against floods, agricultural use and habitats of endangered species, which means there are restrictions on how much water can be stored behind reservoirs if runoff happened earlier in the year, Marshall said. This poses challenges during the summer heat waves, when demand for electricity is rising.

The southwest is less dependent on dams to produce electricity than its northern neighbors, but is facing reduced water capacity as the region dries up. This has important implications for the region’s decarbonisation efforts.

“As we think about what is needed to decarbonise our network, hydro is becoming especially important and useful because it is a renewable energy source that can be turned on and off relatively quickly in response to the presence of wind and sun,” Marshall said.

“Energy emergencies” are expected this summer

The impact of hydropower on the climate is most evident in California, where emissions from power plants are increasing and decreasing depending on the country’s hydropower production.

In 2021, EPA data show that California’s greenhouse gas emissions were 37 million tonnes, the highest level since 2016. This coincided with hydropower production, which is the lowest in the state since 2015, with 14.5 terawatt hours of electricity, according to the US Energy Information Administration. Natural gas production increased a large part of the groin, producing 96.5 TWh of electricity, the highest such figure since 2016.

Golden State also relies heavily on hydropower imports to stabilize the grid during high-demand events, according to NERC. In the event of an extreme peak, total imports into California will increase to approximately 17.4 gigawatts, compared to 13 GW during a normal peak.

In its report, NERC pointed to an “increased risk of energy emergencies” this summer, as dry conditions threaten the availability of hydropower.

“Periods of high demand in a wide area will lead to reduced energy supplies for transmission, which will make operators rely mainly on alternative resources to balance the system, including natural gas generators and battery systems,” warned NERC.

Low water availability makes California particularly vulnerable to the recent rise in natural gas prices, said Fred Hutt, a senior political associate at the NW Energy Coalition. He also points to the need for additional measures to reduce demand and coordinate electricity supplies, which will allow the region to maximize available water resources. Other analysts said improved snow forecasting and monitoring would also allow the region to better predict how many water resources there will be in a given year.

The good news, Heutte said, is that the challenge has prompted network planners in the region to consider how to keep the system up and running in extreme heat.

“You have to be prepared for the unexpected,” he said. Now we are trying to focus more on unexpected problems.

Reprinted from E&E news courtesy of POLITICO, LLC. Copyright 2022. E&E News provides important news for energy and environmental professionals.