ERCOT staff and CPS Energy continue to work “very closely” in negotiating reliability must-run contracts (RMR) for three aging coal-fired units that the grid operator says are necessary for reliability in the San Antonio area.
General Counsel Chad Seely told ERCOT’s Board of Directors on Oct. 10 that the ISO is positioning itself to come before the board during its December meeting for a “full evaluation” of whether the directors want to select one or more of the RMR units.
“This is a big decision for the board to evaluate the local reliability impacts that we have identified as a result of these resources going away and making sure that you have a complete set of information to evaluate the cost/benefits of what your decision may be,” Seely said.
San Antonio’s municipal utility told ERCOT this year that it planned to retire the three coal units, which date back to the 1960s, in March 2025. However, ERCOT said the Braunig Power Station units, with a combined summer seasonal net maximum sustainable rating of 859 MW, were needed for reliability reasons and issued a request for reliability must-run proposals in July. (See ERCOT Evaluating RMR, MRA Options for CPS Plant.)
Complicating matters is that CPS Energy has said each unit must be inspected and repaired — consecutively, not concurrently — if it is to operate beyond its retirement date.
Rick Urrutia, the utility’s vice president of generation operations, said the inspection outage for Braunig Unit 3, the largest (412-MW maximum summer rating) and most desirable RMR resource, will take at least 60 days. That could be delayed by long lead times for needed parts for repairs, he said.
“That schedule can change if we find any major ‘discovery work,’ in which some of that equipment or systems has to have extensive repairs,” Urrutia said.
Negotiations between the two parties have focused on the lost opportunity cost if Unit 3’s outage begins before any RMR service; the outage, inspection and repair processes for all three units; and the costs of any potential RMR service.
CPS Energy agreed to move Unit 3’s suspension date up to March 2 under what ERCOT is characterizing as a pre-RMR agreement. That would improve the odds for its availability and potentially one of the other units for next summer, should the board choose that path, Seely said.
ERCOT says the RMR units will be important in addressing the South Texas export interconnection reliability operating limits (IROLs) staff established this year. Their analysis revealed that under certain conditions, such as when high system demand coincides with an outage of a major transmission line or one or more generation units, lines that deliver power from South Texas into San Antonio could be overloaded and possibly lead to cascading outages.
Potential RMR or must-run alternative service would reduce the loading on the 345-kV lines subject to the IROLs.
An ERCOT solicitation for must-run alternatives (MRA) to the Braunig units resulted in one response. A 200-MW multi-hour energy storage resource responded within minutes of an Oct. 7 deadline, proposing to start in the summer of 2026 and end March 1, 2027.
“That’s a little disappointing that we weren’t able to get more interest from the industry because ultimately, the consumers of Texas will have to pay for any type of solution the board deems appropriate,” Seely said.
The grid operator says the ESR would provide a positive shift factor for the IROL in that it’s north of the South Texas constraint and would reduce loading. Staff will conduct eligibility and qualification analysis of the proposed MRA.
