A fragment of coal that was below a conveyor belt at the Deely plant.
A fragment of coal that was below a conveyor belt at the Deely plant. CPS Energy Calaveras Power Station hosts the Deely and Spruce coal power plants. Credit: Bonnie Arbittier / San Antonio Report

This story has been updated.

While CPS Energy plans to end its use of coal as a power source by 2030, it will be up to the Electric Reliability Council of Texas whether or not the utility will be allowed to do so, CPS Energy officials told a San Antonio City Council committee Tuesday.

In recent years and with San Antonio facing stricter air quality regulations, calls to diversify CPS Energy’s generation portfolio and speed up the closure of the J.K. Spruce power plant — CPS Energy’s last remaining coal plant — have intensified.

The utility has committed to shutter one unit, known as Spruce 1, by 2030 and plans to convert the other unit, Spruce 2, to natural gas by 2028. However, CPS Energy must get the okay from ERCOT, which manages the state’s electrical grid, before doing so, said Benny Ethridge, CPS Energy’s executive vice president of energy supply.

“We have to make a request to ERCOT, and then there’s a lot of modeling that has to occur in terms of what changes need to be made to the electrical grid,” Ethridge told members of the municipal utilities committee. “And so ERCOT will weigh in. Just because we request to shut down a unit in particular does not mean ERCOT won’t require us to extend operations.”

Christy Penders, an ERCOT spokeswoman, explained the process in a statement late Tuesday.

“Once the plant in question provides us with a Notice of Suspension of Operations (NSO) ERCOT performs a Reliability Must Run (RMR) assessment to determine if the retirement of the plant will cause a reliability issue,” the statement said. “If it does, ERCOT may enter into an RMR agreement with the plant. We don’t have a NSO on Spruce at this point, so no RMR study has been completed. Plants must give us at least 150 days’ notice before they can retire.”

Councilwoman Adriana Rocha-Garcia (D4) asked CPS Energy’s President and CEO Rudy Garza if the utility is on track to receive ERCOT’s approval so that the plant can close by 2030.

Garza said the utility needs more direction from its board of trustees on the future of its generation portfolio to answer that question.

“That’s kind of the dynamic — the board has to tell us, ‘Yeah, we’d like to close these plants by 2025 or 2026,’ and then we can start notifying ERCOT, which will tell us whether or not that works with their modeling,” Garza said.

CPS Energy will then need to tell ERCOT exactly where the replacement megawatts will come from before getting permission to take any units offline, he said.

Each Spruce unit contributes roughly 700 megawatts of generation, a CPS Energy spokeswoman said. If its current schedule of plant closures remains on track, CPS Energy will drop roughly 3,000 megawatts of fossil fuel generation out of its portfolio by 2030. One megawatt is enough electricity to power 200 Texas homes on a summer day.

The utility is already in the process of replacing 900 of those megawatts through its FlexPower program, which aims to add up to 900 megawatts of solar, 50 megawatts of energy storage and 500 megawatts of “firming capacity” — likely natural gas — to the utility’s power generation mix over the next 20 years.

CPS Energy’s rate advisory committee is also focused on what the utility’s future generation portfolio should include, and plans to bring its recommendations to the board by December.

The public can weigh in, too. The utility has held one public meeting and plans another for Dec. 1, and has an online survey for those who can’t make it to these meetings.

A footnote on CPS Energy’s Tuesday presentation noted that ERCOT may also require local transmission reliability upgrades to the grid before Spruce’s closure, which typically takes four to five years to install.

CPS Energy has “already got transmission planning in the works,” Garza said, which should help ensure the processes move smoothly and quickly. ERCOT may also allow CPS Energy to close Spruce but require it to use a “bridge fuel,” like natural gas, to make sure those megawatts are readily available until cleaner technologies are more reliable, Garza noted.

“We’re always looking 20 years out, to just alleviate any concern you have that we’re not thinking long term,” Garza told the committee.

Lindsey Carnett covers the environment, science and utilities for the San Antonio Report. A native San Antonian, she graduated from Texas A&M University in 2016 with a degree in telecommunication media...