How utilities are holding up to the power demand during Spokane’s heat wave

The heat is here to stay, at least as far as the National Weather Service forecasts.

Bracing for an unprecedented string of 90-degree days, Avista Utilities said its system is equipped to handle increased energy demands during the continuing heat spells.

The hot weather will linger in Spokane for much longer than the city is used to. The longest stretch of 90-degree days in the city’s history is 15 days in 2017.

Spokane is on track to hit that record by Friday and shows no sign of cooling below the threshold. The National Weather Service’s forecast model doesn’t include a sub-90 day in its outlook that goes into next week.

The weather service’s models indicate an exceptionally stubborn high-pressure ridge is blanketing the Pacific Northwest, fueling the hot, dry weather in the region. This could change by next week, meteorologist Laurie Nisbet said.

“It shows that by next week, it is trying to push a trough into Canada, which would bring us potentially cooler temps – not necessarily below average, but cooler than what we currently have,” Nisbet said.

While it’s hazy to forecast that far out, Nisbet said it could cool down by early next week.

“Once we cool down into the mid-upper 80s, maybe nearing the 90s, it looks like that’s going to stay for a couple of days, maybe to the end of the month,” Nisbet said.

As the region moves through a record string of days above 90 degrees, Avista Utilities and other area power companies believe they have the necessary means to keep air conditioners cooling.

Generally, energy demand increases in warmer weather as people cool their homes and water their lawns, which can put a strain on power supply exacerbated by systems working less efficiently in hot weather.

“We’ll see the demand for electricity creep up the longer it goes,” said Mike Magruder, Avista’s director of transmission operations. “But the system has that margin to be able to handle it.”

Avista increased its capacity for supplying electricity to customers enough with the intent that user demand doesn’t exceed 80% of their capacity during temperatures of 104 degrees or more.

The cushion adds a margin, Magruder said, in the event of higher-than-expected customer demand or a tree falling on a power line. If needed, there’s enough power capacity in other areas to meet these demands, transferring from different sources in their system.

“We need to design the system so that we can have a sustained outage at the peak when it’s hot and still be able to turn the lights back on,” Magruder said. “So that’s why we design in that extra margin.”

During the record-breaking heat wave last week that peaked at 104 degrees Wednesday, Magruder said that user demand was “mostly” below the 80% capacity.

“We have a bunch of substations, so only in certain parts of the system did we push our capacity,” Magruder qualified.

“The system performed as we expected and as it’s designed,” he said.

Customers used less energy in last week’s heat wave than in June 2021, when Spokane was the hottest it’s ever been at 109 degrees.

During the scorcher, targeted blackouts left tens of thousands of Avista customers without power in the unyielding heat. Avista’s systems met their threshold limits earlier than the company expected, and Avista struggled to meet the highest energy demand in the company’s history.

Magruder doesn’t anticipate energy use to reach levels it did in record-setting 2021.

“We do see load generally increasing,” Magruder said, referring to increases during heat waves. “We expect that it will be lower, but close.”

Avista has made several system improvements to increase capacity since the heat dome and accompanying controversial power outages of 2021, Magruder said.

They’ve built new substations and additional transformers to stations, targeting high-demand urban areas that had the most strain in 2021. The West Plains region got a new substation, and Avista rebuilt an existing substation of U.S. Highway 195 to add increased capacity. Idaho towns of Post Falls and Coeur d’Alene also got upgrades to area substations.

“We’ve addressed the areas of concern where we had high load that was approaching capacity,” Magruder said.

The extended temperatures have reduced flows in area streams and rivers, which reduces the power produced by the Bonneville Power Administration, a division of the U.S. Department of Energy that sells electricity generated from 29 federal hydroelectric dams in the Columbia River Basin.

The BPA owns about 65% of the electricity generating capacity and half of the firm energy produced in the Northwest. For scale, it generates enough power to continuously power nine cities the size of Seattle.

“Our streamflow and weather forecasters identified the first major heat wave of the summer more than a week in advance of its arrival, giving us time to prepare and position the federal hydropower and transmission system to be able to address the extended high temperatures being experienced across our service area,” said Kevin Wingert, spokesman for the BPA.

In addition to planning for the heat, the BPA also rescheduled planned outages needed for maintenance. By delaying those actions, it allowed more power to be available.

“Upstream releases for temperature control from Dworshak (Reservoir, near Orofino, Idaho) coincided with the timing of the heat wave, resulting in additional generation on the lower Snake (River) and lower Columbia projects,” Wingert wrote.

Kevin Holland, Avista’s director of energy supply, said that just like BPA, Avista officials monitored the forecasts and reacted accordingly.

Avista owns generating capacity on six dams along the Spokane River and two dams on the Clark Fork River. Together, the dams generate about 48% of the power Avista sells to about 400,000 customers, mostly located in Idaho, Washington and Oregon.

Natural gas-fueled generation plants provide about 33% of the power. Another 9% comes from wind, 8% from a coal plant in Montana, and about 2% comes from biomass sources, according to the Avista website.

“Our energy supply and operations teams have been coordinating for a number of weeks to prepare for this event and keep as much capacity available as possible,” Holland wrote. “Despite the coverage and duration of the heat wave, regional markets continue to provide energy when needed, and prices have remained within expected ranges,” Holland said.

Asked whether Avista has been forced to purchase power, Avista spokeswoman Annie Gannon said the answer is complicated and can change by the hour.

“As an example, during a typical summer day, Avista may purchase energy from the market during the morning or early afternoon, which allows us to store water in our reservoirs to use later when our loads are peaking for the day,” she wrote.

Regardless of the season, that flexibility to buy or sell energy, based on use needs and other factors, leaves the utility “well-suited to meet and exceed expected loads,” Gannon said.

Wingert said the same forces are at play at the larger BPA, which sells power to public and private utilities. Any excess power that’s not needed can then be sold to utilities in Canada, California and elsewhere.

“We have an obligation to serve power to our customers. If we are short, we’ve got to go to the market or find some other way to get that power,” he said. “That’s part of the reason we have reserves for power, is to be able to account for those times.”