AUSTIN, Texas — ERCOT officials issued their first voluntary conservation call of the year Tuesday as the Texas grid flirted with peak-demand records during an oppressive heat wave.
The grid operator asked Texans to voluntarily reduce their electric use between 4 and 8 p.m., “if safe to do so,” because of extreme heat and forecast record demand. ERCOT also requested that the state’s government agencies reduce energy use at their facilities as much as possible.
Demand peaked at 79.2 GW during the hour ending at 6 p.m. Tuesday, the last official day of spring. That fell short of ERCOT’s record peak of 80.1 GW, set in August. It was also short of the new peak record for June, set Monday at 79.3 GW.
The grid operator last week had projected record peak demand of 83.2 GW for Tuesday. (See ERCOT: Prepared for Expected Record Demand.)
“ERCOT is not experiencing any emergency conditions right now,” CEO Pablo Vegas told the Board of Directors during its bimonthly meeting Tuesday.
Vegas told the directors that voluntary conservation is a “very widely used industry tool” to help lower demand during certain times of the day. ERCOT credited the conservation efforts and other reliability tools with surviving the tight periods Tuesday.
As it normally does when ERCOT needs every megawatt possible to meet demand, the Texas Commission on Environmental Quality accepted the grid operator’s request to exercise its enforcement discretion for any generator’s exceedance of the agency’s air-permit limits. The discretion ended at midnight Wednesday.
ERCOT recently rolled out a new notification system to help alert Texans to grid conditions before an emergency is called. Last week, it issued its first weather watch, extending through Wednesday, to draw public attention to potential high demand triggered by extreme hot temperatures. (See “New Grid Notifications Added,” ERCOT Monitor Recommends New Market Design in Report.)
A dangerous heat wave has settled over much of Texas since last week. Humid conditions have sent heat indexes above 120 degrees Fahrenheit in some portions of the state and caused the National Weather Service to issue excessive heat warnings and heat advisories.
ERCOT is expecting demand to exceed 83 GW next Monday and Tuesday. However, its projections have often come up short.
Several cities have set record highs this week, with Laredo hitting 115 F on Monday. That day, Houston reached triple digits a month earlier than normal.
Despite the sizzling temperatures during the waning days of spring, Woody Rickerson, ERCOT’s vice president of system planning and weatherization, told the board that staff are expecting temperatures this summer to be average and not as extreme as last year, the second-hottest summer on record. A developing El Niño and May rains have lessened the chance for above-normal temperatures, Rickerson said.
Solar energy has carried the load for ERCOT, providing as much as 12.2 GW of energy Tuesday, close to its summer-accredited capacity of 12.6 GW, which is up 50% over last year. Rickerson said the increase in solar resources has moved the ISO’s normal summer peak from the 5 p.m. hour to 9 p.m.
“The amount of solar we have on the system has really helped mitigate what used to be our peak hour before,” he said. “Now, we’re a little more worried about moving to the 9 p.m. hour. Load will drop from 5 to 9 p.m., but the solar is dropping more than the load drops, so that makes your tightest hour to be later in the day.”
That makes ERCOT dependent on wind to meet the summer demand, Rickerson said. ERCOT has a little over 10 GW of summer-accredited wind resources, but more than three times that in nameplate capacity.
“That’s the reality of where we are. Every day, we’re going to have to look at what the wind is doing,” he said.
