Climate-fueled heatwave will hamper western hydroelectric power generation

CLIMATE SENTENCE | When California experiences a heat wave, it relies heavily on hydroelectric power from the Pacific Northwest to power its lights.

But those hydroelectric plants may not always be available when they are needed most, as climate change shifts the soil where the Western dams are located. Higher temperatures mean snowmelt occurs earlier in the year and leaves less water for electricity generation during the summer. The result is an increased risk of blackouts during extreme heat waves as a result of less water availability, according to a report this week from North American Electric Reliability Corp. (NERC).

The report highlights the paradox of running regional power grids in a warming world: As energy demand increases with temperature, there may be less hydro available to supply electricity, increasing demand for fossil fuels.

“In general, hydro is the low-carbon source of electricity needed to tackle climate change,” said Steve Clemmer, director of energy research at the Union of Concerned Scientists. “At the same time, it is a power source that is affected by climate change.”

According to NERC, the biggest threat to the West is heat waves like the ones that hit cities from Seattle to Tucson in 2020 (energy wire, May 19). Hotter temperatures are weighing on the network as soaring demand means there is less spare power to send from one part of the region to another. The risk of blackouts is especially acute in the early hours of the night, when solar output begins to fall but electricity demand remains high.

It is against this background that hydroelectric power generation becomes very important. A study recently published in the journal Earth’s Future found that water availability and summer air temperature are likely to be the biggest determinants of Western electricity prices in the coming decades.

“If we have a heatwave that increases demand, that’s when the loss of hydro becomes very important,” said Adrienne Marshall, a computational hydrologist at the Colorado School of Mines.

The challenges vary in different parts of the West, he said. Scientists generally expect temperate regions of the world to be wetter and dry areas drier as temperatures rise.

Problems in the Northwest are seasonal. Many dams in the region are subject to regulations requiring them to manage water levels for flood protection, agricultural use, and habitat for endangered species, meaning there is a limit to how much water can be stored behind the embankments if runoff occurs earlier in the year, Marshall said. . That presents a challenge during a summer heatwave, when electricity demand spikes.

The Southwest is less dependent on dams to generate electricity than its northern neighbour, but is facing declining water output as the region becomes drier. That has important implications for the region’s decarbonization efforts.

“When we think about what it takes to decarbonize our grid, hydro becomes very important and useful because it is a renewable energy source that can be turned on and off relatively quickly in response to wind and solar availability,” Marshall said.

‘Energy emergency’ is expected this summer

The climate impacts of water availability are most visible in California, where power generation emissions rise and fall depending on the state’s water output.

In 2021, EPA data showed that California’s greenhouse gas emissions were 37 million tonnes, the highest level since 2016. That coincides with hydroelectricity being the state’s lowest since 2015, at 14.5 terawatt-hours of electricity, according to Administration figures. US Energy Information. Natural gas generation took up many of the shortfalls, generating 96.5 TWh of electricity, the highest figure since 2016.

Golden State also relies heavily on hydropower imports to stabilize the grid during high-demand events, according to NERC. In an extreme peak event, California’s total imports would increase to about 17.4 gigawatts, up from 13 GW during a normal peak.

In its report, NERC pointed to a “high risk of an energy emergency” this summer as dry conditions threaten hydropower availability.

“A period of high demand over a large area will result in a reduced supply of energy for transfers, causing operators to rely primarily on alternative power sources for system balancing, including natural gas-fired generators and battery systems,” warns NERC.

Low hydro availability makes California particularly vulnerable to recent increases in natural gas prices, said Fred Heutte, senior policy fellow at the NW Energy Coalition. It also points to the need for further action to reduce demand and coordinate the delivery of electricity supply, which will allow the region to maximize the available hydro resources. Other analysts say improved forecasting and monitoring of snow packs will also allow the region to better predict how much hydro it will have in any given year.

The good news, Heutte says, is that the challenges have prompted network planners in the region to think about how to keep systems running during extreme heat events.

“You have to be prepared for the unexpected,” he said. “This is an unexpected issue that we are trying to focus more on now.”

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

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