Texas’ electric grid operator declared a Level 1 power emergency on Wednesday afternoon and came close to going to a higher state of emergency as power generation reserves dropped below 2,300 megawatts.
This was the second day in a row the Electric Reliability Council of Texas called such an emergency. ERCOT asked all available power plants to come online, began drawing on power from neighboring grids, including Mexico, and asked consumers to cut back usage through 7 p.m.
And for the third day in a row the state broke the record for power use, with 68,294 megawatts used during the 4 p.m. to 5 p.m. hour. That broke the record set Tuesday of 67,929 megawatts.
ERCOT originally said it thought it would have to declare a Level 2A emergency, but the peak hour passed without operators having to take the next step, said Kent Saathoff, ERCOT’s vice president of system planning and operations.
“We were within about 50 megawatts of going to Level 2,” Saathoff said in a conference call Wednesday afternoon.
A Level 2A emergency is called if reserves drop below 1,750 megawatts. At that time industrial customers who have agreed previously to shut-down equipment in an emergency would be called on. That would relieve the system of about 1,000 megawatts of demand.
At Level 2B, when reserves are continuing to drop, another group of commercial customers would be called on to cut off their power use. That group accounts for about 300 megawatts of demand.
At Level 3 emergency is called when the outages begin to threaten the integrity of the entire grid. At that point local utilities — such as CenterPoint Energy in the Houston area — would be called on to do rotating blackouts, where certain circuits are cut off for 15 to 45 minutes — or longer — at a time.
As much as 4,000 megawatts of power capacity was offline unexpectedly on Wednesday, helping to squeeze the margin between supply and demand as the state headed into the peak usage hours late in the afternoon.
The number of power plants offline unexpectedly on Wednesday was slightly higher than on Tuesday, Saathoff said, but it’s not unusual for about 5 percent of the state’s roughly 70,000 megawatts of power plant capacity to go offline in the summer.
One megawatt of power is enough electricity to power about 200 homes in Texas during hot weather when air conditioners are running for long periods of time.
Texas was still several steps away from rolling blackouts, which have only occurred three times in the past few decades. The most recent occurrence was in February, when a sustained cold snap led to the failure of dozens of power plants.
The extreme hot and cold weather in Texas this year has “certainly been weird” Saathoff said, but he’s not sure if the events will necessarily lead to radical changes in the state’s power system.
“You can’t afford to build a system that will give you 100 percent reliability,” Saathoff said. “It’s a question of what extreme events do you design and build a system for.”
Grid operators are expecting Thursday and Friday to also be days that see high electricity demand. Consumers are being encouraged to reduce their usage, particularly from 3 p.m. to 7 p.m. both days.