Last week, wind contributed more to power generation than coal for about 30 hours on the grid NorthWestern Energy oversees, according to data from the U.S. Energy Information Administration.
And for more than five days, generation from coal fell to nearly half its capacity, according to EIA data for the same region and period.
“It very much challenges and undermines the framing that fossil fuels run 24-7 and keep our lights on,” said Karin Kirk, a science writer for NASA Climate and journalist for Yale Climate Connections.
During the weekend, Montana hit record-cold temperatures, and Wednesday, NorthWestern Energy touted its ability to keep the lights on and heaters running.
In a news release, the utility monopoly highlighted the contributions fossil fuels made during the record high demand, and NorthWestern CEO Brian Bird offered praise for crews and customers.
“We appreciate the patience of those who were affected by some outages our system experienced and the numerous accolades offered for our crews working around the clock in extreme conditions to keep the lights and heat on,” Bird said in a statement.
Kirk and energy analysts also praised the ability of the utility to operate during the Arctic blast, but they said NorthWestern Energy omitted important information in its announcement about how it met record demand, and a look at federal data shows a more complex picture.
For one thing, Colstrip wasn’t running at full capacity for most of last week. EIA data showed it finally got back up to capacity on Saturday when NorthWestern said energy demand hit the record high.
NorthWestern Energy spokesperson Jo Dee Black said Colstrip Unit 4 was down for “scheduled maintenance,” and half of the company’s 222 megawatts were available from Unit 3 through a reciprocal agreement.
NorthWestern didn’t address by press time what the maintenance was for. NorthWestern also didn’t address whether it’s typical to schedule a plant to be offline for such a long stretch in the middle of winter, but the plant is old and has broken down before.
However, in its news release, NorthWestern Energy said if it had Avista’s 222-megawatt share of Colstrip, which it will acquire on Jan. 1, 2026, it could have avoided more than $18 million in purchases from the energy market.
“More than five days of consecutive extreme temperatures across Montana illustrates why additional 24/7, on-demand resources located in Montana and dedicated to serving our Montana customers are needed to reduce the risk to reliable service during extreme weather,” Bird said. “And in order to add even more variable wind and solar generation to the Montana grid, we need more of the same 24/7 generation to keep the grid stable.”
The company noted Colstrip, natural-gas-fired generation facilities, and hydro generation in Montana supplied half of the power for customers, and it said it had to buy power from the energy market to meet more than half of the demand in Montana.
“Wind and solar generation could not produce much, if any, power during the extreme cold,” NorthWestern said.
Anne Hedges, with the Montana Environmental Information Center, agreed wind wasn’t supplying much power during the most frigid portion of the cold snap, but she said there’s more to the story.
“That should not be the end of the conversation,” Hedges said.
She said NorthWestern is still in an “infant stage” when it comes to energy, looking to technology that’s 15 or 20 years old, and customers are paying the price.
For example, other more advanced “grown up” utilities are investing in battery storage units that can hold up to 100 hours of energy, and often, wind blows quite a bit ahead of a storm, as it did last week, she said.
“We could have stored that up and used that electricity over the course of the weekend,” Hedges said.
But NorthWestern isn’t capturing that energy when it’s available, she said, and it isn’t taking advantage of storage technology that allows utilities to meet demand over a longer period of time.
“They’re acting like energy is something that is either on or off,” she said.
Kyle Unruh, with Renewable NorthWest, said wind ramps up and down, and it did so last week, dropping to essentially zero at one point. However, he said wind also contributed significantly, some 350 megawatts, for many hours while loads were nearing a peak.
“And if we had more wind on our system, it would have contributed more,” Unruh said.
NorthWestern did not cite any plans to invest in wind generation and storage capacity in the near future. It said decisions about adding wind generation and storage “would be made after projects are identified in a request for proposals.”
In the U.S. in general, the use of renewable energy is up.
A report this month from the Union of Concerned Scientists notes renewables provided more than 22% of the country’s electricity, nearly twice the amount since in 2012, citing EIA data.
The report, about gas plant malfunctions, also notes gas plants are more vulnerable to breakdowns than people assume, which create a “vulnerability for the power grid and for customers.”
NorthWestern is building such a plant in Laurel, and in its news release, it featured that facility as well.
“If the 175 megawatt Yellowstone County Generating Station, the natural-gas fired generation plant NorthWestern Energy is completing south of Laurel, was operating during this Arctic blast in Montana, more than $14 million in purchases from the energy market would have been avoided,” NorthWestern said.
But a natural gas plant in Washington failed during the cold stretch, contradicting a common narrative that fossil fuels never miss a beat, Kirk said. She and Hedges also said energy purchases are standard for a utility, and the market worked as intended.
“Energy is a tradable commodity,” Kirk said. “The grid only works because of all of that trading. Otherwise, everyone would be really overbuilt.”
And if everyone had to cover their own peaks all of the time, power would be too expensive, she said. Kirk likened the situation to complaining about a $600 airfare ticket by saying, “If only I owned my own airplane.”
Hedges agreed with NorthWestern’s pronouncement that Colstrip was important to keeping the lights on last week. But, she said the full picture shows the Colstrip plant is old and having more and more trouble.
“It needs to be replaced by something else. It is increasingly breaking down, so let’s talk about what comes next,” Hedges said.
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