Colstrip Power Plant is operating fully again, after a summer of unit shutdowns due to air pollution problems.
The four-unit coal-fired power plant’s biggest generators, Units 3 and 4, were forced to shut down in late June after failing to pass Mercury and Air Toxics Standards. The units account for 70 percent of Colstrip’s generating capacity. It took most of the summer to get the units' pollution problems fixed, with power plant co-owner NorthWestern Energy telling state officials at August’s end that operations would normalize soon.
By mid-September pollution tests on the units indicated they were again within range, according to power plant operator Talen Energy, which has been working with the state Department of Environmental Quality on pollution testing.
“Earlier this month, testing demonstrated that Colstrip Steam Electric Station’s Units 3 and 4 are again operating in compliance with the filterable particulate matter limit established by the federal Mercury and Air Toxics Standard,” said Taryne Williams, Talen spokeswoman, in an email. “As a result, all four Colstrip units are fully operational and will be run as electric system conditions dictate. Colstrip personnel are continuing to work with the Montana Department of Environmental Quality’s Air Quality Bureau to satisfactorily address the compliance deviation that occurred in June.”
The June shutdown of Units 3 and 4 occurred while Units 1 and 2 were already scheduled to be offline. Federal pollution laws require power plants to keep levels of airborne mercury and hazardous air pollutants below 0.03 pounds per million British thermal units. In the second quarter of 2018, pollution levels for Units 3 and 4 were running high. Unit 3 was 1.43 times higher than acceptable levels and unit 4 was 1.7 time higher, according to data released by DEQ. Colstrip’s problems were specifically tied to hazardous air pollutants, or HAPS.
HAPS are pollutants that are known to cause cancer, or are suspected of causing cancer and other serious health problems like birth defects. The toxic ingredients include lead, cadmium, chromium and other compounds.
Talen has not disclosed the cost of repairing the units. DEQ Air Bureau Chief Dave Klemp said Friday that he doesn’t yet know what steps Talen had to take to get Units 3 and 4 to operate correctly.
Test results on all four units are still being analyzed to determine whether the power plant will pass MATS standards for the third quarter. Those results won’t be finalized until sometime in November.
Getting Units 3 and 4 back online was crucial for the power plant’s namesake community of 2,300. The power plant is in decline, with Units 1 and 2 scheduled for shutdown no later than 2022 in order to settle an air pollution lawsuit. Units 3 and 4 have been expected to burn into the 2030s.
The power plant is owned by Pennsylvania-based Talen and five state-regulated utilities in the Northwestern United States. Montana's largest utility, NorthWestern Energy, is a stakeholder.
Two of those utility owners, Puget Sound Energy and Avista Corp., of Washington, have set Dec. 31, 2027, as the date they will be financially ready to shutter the power plant. Portland General Electric is obligated by Oregon law to wind down its use of coal power by 2030 and stop using coal energy entirely by 2035. PacifiCorp is obligated to stop selling coal power to its Oregon customers by 2030.
NorthWestern, which once expected Colstrip to run into the mid-2040s, has trimmed a decade off of that projection.