The state’s main power grid narrowly avoided outages on Monday after several power plants failed as electricity demand soared in response to the coldest weather in two years.
But the loss of just one more large power plant could have pushed the grid over the edge, Dan Woodfin, ERCOT director of system operations, told reporters during a conference call. The grid lost two big power plants to weather-related problems and some others to other problems, totaling about 3,700 megawatts of power, Woodfin said.
During that time, the state imported about 800 megawatts from the nation’s eastern power grid and 180 megawatts from Mexico. A megawatt is enough to supply about 200 Texas homes during a period of peak usage and about 500 homes during routine usage.
As the Arctic air settled in across North Texas on Monday morning, temperatures plunged into the teens and wind chills dropped to the single digits.
At Dallas/Fort Worth Airport, the low was 15 degrees, the coldest since the ice storm during Super Bowl week in February 2011. On Feb. 2, 2011, the temperature dropped to 13 degrees and on Feb. 10, 2011, it dropped to 15. The overnight low was 19, and Tuesday’s high is expected to be in the mid-40s.
While Monday’s low was not a record-breaker — that came in 1912 when it got down to 11 degrees — it hadn’t been that cold on Jan. 6 since 1924, when it also reached 15.
Alliance Airport dropped to 10 degrees shortly after 7 a.m. Monday and recorded a wind chill of minus 1. At D/FW Airport, the coldest wind chill recorded was 1 degree above zero.
This was still far warmer than the coldest temperatures on record for the Dallas-Fort Worth area. On Feb. 12, 1899, the temperature dropped to minus 8 degrees. It reached 2 below zero on Jan. 31, 1949, and it has reached minus 1 twice, most recently on Dec. 23, 1989.
Temperatures were back in the teens Tuesday morning across North Texas, and concerns about energy consumption continued as some parts of the state including Houston were expected to see lower temperatures than Monday. No outages were reported early Tuesday.
Better prepared for cold
Power demand in Texas peaks during the summer as air conditioners fire up. But about half of Texas residences use electricity rather than natural gas for heat during the winter, and electric-resistance furnaces are especially energy-hungry.
Even though ERCOT avoided outages Monday, power companies paid hefty prices to buy electricity during the emergency alert period, when wholesale prices for one hour topped the state’s regulatory ceiling of $5,000 per megawatt-hour, Woodfin said. That’s about 100 times the $50 per megawatt-hour price generally seen.
The state Public Utility Commission has been raising the ceiling in an effort to encourage generators to build more plants to meet growing demand. Prices can sometimes exceed that ceiling after additional costs related to moving the power on the grid are included.
ERCOT said demand for electricity Monday reached 55,486 megawatts between 7 and 8 a.m. That’s short of the record winter demand of 57,265 megawatts on Feb. 10, 2011, which produced rotating outages, and also lower than peak demand during last month’s run of low temperatures, ERCOT spokeswoman Robbie Searcy said.
But just as in 2011, some generators were incapacitated by the cold on Monday, although not nearly as many. The two big North Central Texas plants that went down “both were related to freezing of instrumentation used to provide control of the plants,” Woodfin said. The units were not identified.
Woodfin said ERCOT and Texas regulators implemented “best practices” standards for weatherization of power plants after the 2011 outages, and he thought the relatively few generators with problems Monday showed that the state had improved its ability to avoid cold-related problems. Among the changes: requiring effective insulation, heaters and wind screens to protect sensors and hydraulic lines needed by power plants to operate.
Luminant spokesman Brad Watson said Monday that “all available Luminant power plants were operating this morning, and we’re not aware at this time of weather impacting generation.” He said the company does not comment on operations at specific plants, although he did say output at Comanche Peak was reduced at one of its two nuclear reactors.
ERCOT asked residents to set their thermostats no higher than 68 degrees and turn off and unplug nonessential lights and appliances. It was also advising individuals not to run large appliances such as washers, dryers and electric ovens during peak hours — 6-9 a.m. and 4-8 p.m. Businesses are also advised to minimize the use of electric lighting and electricity-consuming equipment as much as possible.
About 300 customers remained without power Monday evening in Burleson as a result of an equipment failure, a company spokesman said.
The frigid weather this winter across much of the U.S. can be attributed to a dip in the jet stream that has brought cold air south across the Midwest and down into Texas. But National Weather Service meteorologist Jesse Moore said it’s having implications beyond the U.S.
“The jet stream has basically dived southeast of the Rockies and it heads back north off of the East Coast,” Moore said. “They’ve been getting big storms in the United Kingdom. We’ve gotten the cold air here, but the jet stream pushes back up north toward Europe, giving them warmer, windier weather.”
The Arctic air is expected to give way to milder weather the rest of the week. Highs in Dallas-Fort Worth should be in the mid-40s on Tuesday, the 50s on Wednesday and back in the 60s on Friday. Forecasters are also predicting a chance of rain from Wednesday through Saturday after the freezing temperatures have left the area.
“We actually start warming up tomorrow, but it will be more noticeable on Wednesday,” Moore said.