PJM Generation and Transmission Resources Reliably Served Demand During July Heatwave


PJM detailed conservative measures taken to ensure reliability in advance of the late-July heatwave at the Aug. 10 meeting of the Operating Committee.

Ten Hot Weather Alert events coincided with four heat spells during July, the most severe occurring July 27-29, said Donnie Bielak – Senior Manager, PJM Dispatch.

To conservatively prepare for the forecasted heat in late July, PJM issued several types of alerts to inform members to prepare to meet extreme hot weather demand.

The first of these was a maintenance outage recall, which PJM called on July 23 in advance of heavy electricity loads forecasted for July 27-28. This notification successfully recalled generation units back to operation readiness from previously scheduled maintenance outages, he said. PJM may recall generation back to service from maintenance outages up to 72 hours in advance. It was the first use of this procedure in 2023.

On July 24, PJM also issued a Unit Startup Notification Alert to notify units with start-up times greater than 48 hours to prepare to come online if necessary.

On evenings prior to the operating days of July 27 and July 28, PJM also issued Maximum Generation Emergency/Load Management Alerts as informational notices to all generators to be prepared to serve expected heavy load conditions across the PJM region and to let them know that load management tools such as demand response may be used. Demand response customers are contractually bound to reduce energy usage when called upon and receive compensation for the service they provide.

On July 27 and July 28, rain and storms ended up suppressing the forecasted temperatures, and load reached about 147,800 MW on July 27 and about 145,400 MW on July 28. PJM had conservatively prepared to serve loads in the low to mid-150,000 MW range, based on weather forecasts, Bielak said.

PJM cancelled the RTO-wide Maximum Generation Alert/Load Management Alert at 5 p.m. on July 28 along with the NERC EEA-1 Alert, which is issued along with a Maximum Generation Alert. 

A Hot Weather Alert remained in effect for PJM’s Mid-Atlantic and Southern regions through July 29.

 “We had sufficient generation online, and general performance was pretty strong from the transmission and generation side during this hot weather event,” Bielak said.

The all-time recorded peak electricity demand on PJM was 165,563 MW on August 2, 2006.