As a coal mine closes, solar comes on

Craig’s Trapper Mine began operations in 1977. In Severance, Black Hollow Solar is being completed as Colorado moves beyond 50% renewables

by Allen Best

One chapter ended and another began this week in Colorado’s book-length transition from coal combustion to renewable generation of electricity. Both involved Platte River Power Authority, which delivers electricity to four municipalities along the northern Front Range.

On Wednesday, Platte River celebrated completion of a major solar project east of Fort Collins within the municipal limits of Severance. Called Black Hollow Sun, the 257-megawatt project will provide electricity for Longmont, Estes Park, Loveland and Fort Collins. Planned since roughly 2019, it is part of a surge in utility-scale solar projects coming online during the next few years.

About 250 miles to the west, the last coal was scooped from the open-pit Trappers Mine adjacent to the Craig Generating Station on Sept. 25 after 49 years of operation. This milestone is being celebrated this Friday. All three of the adjoining three units are to be closed before 2029. Coal has been stockpiled from Trappers and Colowyo, another coal mine near Craig that closed last year. Tri-State Generation and Transmission, the operator, is evaluating its options if more is needed. Platte River owns 27% of Trappers.

Also during the last week came news that Colorado altogether had achieved a tipping point in its electricity. For the previous 12 months, according to Energy Information Administration data, more than 50% of electricity had come from renewables. That was a first — and almost certain to be the norm.

Jason Frisbie, CEO of Platte River Power Authority, says the utility by 2030 will be delivering electricity to its four municipal members well in excess of 80% from non-carbon sources. Top, transmission lines are crucial in Black Hollow Sun and other renewable energy projects. Photos/Allen Best

As for Platte River, directors representing the four member municipalities in 2018 adopted a heavily footnoted goal of achieving 100% renewable electricity by 2030. The 544,740 solar panels of Black Hollow alone won’t get Platte River across that finish line but will help immensely. Jason Frisbie, the CEO of Platte River, said at the ribbon-cutting ceremony that he is confident Platte River will get “well in excess of 80% non-carbon energy” by 2030 while maintaining affordability and reliability.

Cost has not been a problem in this big energy pivot, at least not yet. Economics had already aligned in 2019 when state legislators targeted an 80% reduction in emissions from electrical generation by 2030.

Some politicians blamed renewables for rising rates by Xcel Energy and others. The real causes are far more complex. Consider Holy Cross Energy, which this year has achieved 90% renewables through August while still having some of Colorado’s lowest electricity rates.

Ensuring reliability as we expand the role of renewables in our energy mix will be more challenging. One strategy lies in expanded transmission and broader markets, connecting consumers and producers in areas larger than one time zone or one weather system. Just last week, the U.S. Department of Energy announced two grants of $250 million each for projects that would connect Colorado with Kansas, Oklahoma and other states in the Eastern interconnection grid.

Storage will help. Platte River expects the 100-megawatt four-hour discharge lithium-ion-phosphate battery storage project next to Black Hollow Solar to be completed in December.

Other battery chemistries being developed may provide longer-duration storage than the lithium-ion batteries.

Some solutions are smaller and closer to home, sometimes literally. For example, several Colorado utilities help homeowners install Tesla Powerwall batteries that can then be tapped by the utilities to meet peak demand, such as from air conditioners on hot summer evenings. EV batteries or, in the case of a new Xcel Energy program in Jefferson County, school buses, can be used in the same way.

A natural gas plant with the ability to respond quickly to needs is expected to be in place before the Rawhide coal plant is retired. Older natural gas plants required 18 minutes, and coal plants 18 to 24 hours. Photo/Allen Best

To the dismay of some environmental advocates, most utilities want natural gas as a backup. For example, Platte River is spending $600 million on a plant that uses newer technology that can generate electricity almost instantly as needed to balance the variability of renewables. It will become available in late 2029 just before Rawhide, the coal plant north of Fort Collins, closes.

Benefits from this transition have been unequal. The town of Severance will benefit from $500 million in the assessed valuation of Black Hollow on land previously used for low-value livestock grazing. Mayor Matthew Fries says the project will help Severance start several other projects in the town’s core, but did not provide details.

Craig and Moffat County benefit from cushions extended by departing utilities but the community is still trying to figure out its future.

This big pivot from combustion of fossil fuels to emissions-free renewables in generating Colorado’s electricity hasn’t been as quick or as elegant as a ballet dancer’s pirouette. It’s taking time. On Wednesday, as the solar panels were being celebrated, in the background a drilling rig labored on, looking for fossil fuels. But clearly, there is strong movement forward, as evident in the events this week.