Last month's plea for Texans to conserve electricity — despite seemingly typical mid-June weather — was triggered by breakdowns at some of the same power plants that failed during February’s winter freeze, when extended blackouts contributed to dozens of deaths and millions of dollars in property damage.
The repeat problems are heightening concerns about the reliability of the state's power grid and whether state leaders have done enough to shore it up.
The Electric Reliability Council of Texas, the state agency that operates the grid, last week released a list of generators that had unplanned outages in June — meaning they were unexpectedly removed from service by their owners for repairs or were forced to operate at reduced output.
So much generation capacity was idle due to unplanned outages during the week of June 14 that ERCOT issued a systemwide call for Texans to cut back on electricity use to head off the need for emergency measures, such as rolling blackouts. ERCOT's plea — coming before summer even started and when the hottest days of the year had yet to arrive — stunned many people still reeling from the near collapse of the grid just four months earlier.
According to an American-Statesman analysis, 109 of 155 generators, or 70%, that had unplanned outages beginning at various points June 12-17 — the period just before ERCOT's conservation appeal started and just before it ended — also had been forced offline during the winter storm in February.
Slightly more than half the generators with repeat problems, or 57 of them, are fueled by natural gas or coal, and 51 are powered by wind or solar energy. The fuel source for one of the generators wasn't available.
"In February, you at least had the excuse that we were experiencing temperatures that were extremely rare for the state," said Mark Jones, senior research fellow at the University of Houston's Hobby School of Public Affairs.
"But the fact that these same plants went offline in normal weather (for June) means their problems go beyond insufficient weatherization for freezing temperatures and perhaps reveals an underlying lack of sufficient maintenance," Jones said. "It suggests (the plants') maintenance standards are inferior to what should be the norm."
Wholesale prices on the deregulated ERCOT power market soared last month when it appeared electricity was in short supply relative to demand. The price shot up to $1,828.65 per megawatt-hour on June 13 and $1,952.86 on June 14 after topping out at $31.52 on June 11.
The generators that had unplanned outages beginning June 12-17 and during the February freeze are key components of power plants owned by Fortune 500 companies, such as NRG, Calpine and Vistra, as well by municipalities, electric cooperatives and other entities around the state.
Units powered by natural gas and coal have a higher generating capacity on average than those powered by wind and solar energy. The natural gas and coal generators with repeat problems have a combined capacity of more than 14,000 megawatts, while those powered by wind and solar energy have a combined capacity of about 6,800.
Overall, there were nearly 1,300 unplanned outages at generation units during June, although that figure includes multiple outages reported for the same generators. Many more individual generation units — a total of 585 — suffered outages or reduced output during the February freeze than the 155 that went offline June 12-17.
The information that ERCOT released doesn't include details of what caused the June outages. But the agency has said it's investigating the issue and has submitted official requests for information to the plant operators.
"We hope to better understand whether there are any commonalities in those unplanned outages due to things like supply chain issues or routine maintenance delays resulting from the February winter storm," ERCOT spokeswoman Leslie Sopko said in a statement.
But some observers said the fact that ERCOT and the Texas Public Utility Commission — which oversees ERCOT — are in the dark about what happened isn't reassuring.
“It certainly implies a failure of the oversight of our grid at some level," said Chrysta Castañeda, an oil and gas attorney.
“Why are these same entities going down multiple times?" she said. "If something happens repeatedly, there is clearly a problem beyond just mere happenstance or accidents."
Castañeda, who ran unsuccessfully last year for a seat on the Texas Railroad Commission, said the agencies with responsibility for overseeing the grid should be informed immediately and told why when a power company unexpectedly takes one of its generators offline.
Representatives of both NRG and Vistra told the American-Statesman that the outages at their generators beginning June 12-17 weren't related to the issues in February and don't signal larger problems with reliability of their facilities. Ten NRG generators that suffered outages in February also had outages that began June 12-17, according to ERCOT data, and four Vistra generators did the same.
A Calpine representative didn't respond to requests for comment Friday. Eight Calpine generators that had unplanned outages beginning June 12-17 also had outages in February.
Lawmakers approved changes to oversight and operations of the ERCOT grid during the regular session of the state Legislature that ended in May, with the aim of preventing another February-style calamity.
The measures have yet to take full effect, but critics of them — including both Castañeda and Jones — have said they probably lack the teeth even to head off future iterations of last month's scare.
Texas Gov. Greg Abbott has disagreed, and he recently opted against adding the topic of additional grid reforms to a special legislative session that began Thursday.
“Everything that needed to be done was done to fix the power grid in Texas,” Abbott said in early June — just six days before ERCOT issued its weeklong plea for Texans to cut back on their electricity usage because demand risked outstripping supply.
However, Abbott issued several mandates to the PUC last Tuesday that take aim at the growing renewable energy sector. Abbott directed the agency to create subsidies for existing coal, natural gas and nuclear facilities and added "reliability costs" for generators powered by wind and solar energy because of the intermittent nature of their production.
Critics have called the move an effort to scapegoat the renewable energy sector for the overall reliability problems that have been plaguing the Texas power grid.
This article originally appeared on Austin American-Statesman: ERCOT power plants that failed in February saw repeat problems in June