Xcel Energy’s chronically troubled coal plant Comanche 3, scheduled for retirement by the end of 2030, hasn’t been working since mid-August and could be out of service until next summer.
The coal plant in Pueblo County experienced elevated vibration levels Aug. 12, resulting in an equipment malfunction and damage to the unit, Xcel Energy spokeswoman Michelle Aguayo said in an email. The company is working with consulting engineers to determine what caused the problem and to resolve it.
Aguayo said Xcel won’t have an estimated time for returning the unit to service until the investigation is completed. “The preliminary working date for the unit’s return to service, however, is June of 2026.”
With Comanche 3 out of service, Xcel is adjusting the operation of its other generating units, Aguayo said.
Cindy Schonhaut, director of the Colorado Utility Consumer Advocate office, said in an email that customers shouldn’t bear the burden of covering Comanche 3’s repair costs. And the costs of “replacement power should also not fall in the lap of customers,” she said.
Ensuring safe and reliable power is at the forefront of the utility’s responsibility, Schonhaut said. To the extent that Comanche 3 being down affects Xcel’s ability to meet that responsibility, the advocate’s office “has a heightened sense of concern.”
The advocate’s office, which represents the public before the PUC, said it will review Xcel’s cost-recovery requests submitted to the PUC.
Comanche 3 is one of three units on the 700-acre campus of Xcel Energy’s coal-fired generating power station about 11 miles southeast of Pueblo. One unit was closed in 2022 and another will be shut down this year.
The third unit, which would be Xcel’s last coal plant, is scheduled to close by the end of 2030. Xcel, Colorado’s largest electric utility, has proposed replacing the coal plant with wind and solar power, battery storage and natural gas generation.
Comanche 3 started operating in 2010 and originally was expected to run until 2070, but it has been plagued with problems and has experienced numerous outages through the years.
A 2021 report by the Colorado Public Utilities Commission said the coal unit averaged 91.5 days per year of outages over a decade and was out of commission for all but a handful of days in 2020. A quarterly report by Xcel to the PUC showed eight outages at Comanche 3 in July.
The unit has been “a problem child” from the beginning, said Parks Barroso, an attorney and Colorado Clean Energy Manager for the conservation organization Western Resource Advocates.
“I think the Xcel system in Colorado has been planning for a life without Comanche 3 for quite a while now and the system and the renewables on the system have shown that we can meet the system needs without that coal unit,” Barroso said.
Other Xcel Energy coal plants struggled to stay online this summer, according to an analysis by the PUC staff. The report highlighted what Xcel called a “code orange” event, meaning there was a realistic possibility of not having enough power to meet the demand for electricity. The utility asked customers to conserve energy Aug. 7 to avoid managed, rotating blackouts.
The PUC staff said factors that contributed to strain on the electric grid that day included significant outages at other fossil-fuel power plants, sustained high temperatures and lower-than-typical renewable power production levels.
Over 80% of the power that was unavailable on the Xcel system Aug. 6-9 was associated with coal resources, the PUC staff said. Eleven units experienced unplanned outages.
Erin O’Neill, the PUC’s deputy director of fixed utilities, attributed some of the issues to the fact that the coal plants are being phased out.
“We have been trying to make sure we don’t overinvest on maintenance on units that are being converted to other fuel or are reaching their retirement date,” O’Neill said during a recent PUC meeting.
Although the renewable energy generation levels were lower than what’s typical for the time of year, Neill said in an email that they were consistent with the levels used by planners looking to meet demands during peak periods.
However, Xcel Energy overall was short 643 megawatts of its planning target for the summer, or the amount of electricity needed to meet anticipated demands. The target includes a reserve margin to cover possible outages or other contingencies.
A one-megawatt facility could power about 340 homes.
The PUC report said that responses to Xcel’s call for conservation Aug. 7 saved about 525 megawatts of electricity during the hours of peak demand. The measures included people using smart thermostats to lower the draw on air conditioning and commercial customers lowering demand.
Aguayo said Xcel Energy has taken several steps through the years to meet the growing need for more resources, including expanding power plants, approving short-term extensions of agreements with other power providers and a recent request to speed up approval of renewable energy projects to take advantage of federal incentives being phased out.
Get more business news by signing up for our Economy Now newsletter.