PJM Issued First Backup-Generator Warnings During Heat Wave

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PJM Issued First Backup-Generator Warnings During Heat Wave
The new warnings process saw its first operational use as PJM neared record demand, but the grid operator says no large-load backup generators were called to run.
PJM issued “Transmission Security – Emergency Use of Backup-Generator Warning” during this month’s record-setting heat wave, but ultimately did not call on large-load customers to operate their backup generators, the grid operator confirmed.
The warnings were sent on July 2 in the Mid-Atlantic and Dominion regions and again on July 3 in Dominion, according to a July 9 presentation to PJM’s Operating Committee. The alerts followed a US Department of Energy (DOE) emergency order under Section 202(c) that allowed certain large-load customers to shift to on-site generation if needed to protect grid reliability.
PJM now says the warnings were precautionary. The grid operator never escalated to an “Emergency Use of Backup-Generators Action,” meaning no customer-owned backup generators were dispatched under the new procedure.
For operators, the episode offers the first real-world test of a new reliability tool designed to tap into large-load backup generation during grid emergencies. Although the procedure was not fully activated, the warnings demonstrate that PJM was prepared to use it as electricity demand approached record levels.
First Use of PJM’s Backup-Generator Warning
PJM added the emergency backup-generator procedures to its operating manuals this year amid growing reliability concerns and the DOE’s 202(c) emergency order. Under the process, transmission owners report how much large-load demand could be transferred to backup generation within 15 minutes if PJM requests action during an emergency.
In its July 9 Operating Committee presentation, PJM placed the backup-generator warnings among a series of measures deployed as temperatures climbed across the region. Those actions included DOE coordination beginning June 26, North American Electric Reliability Corporation (NERC) Energy Emergency Alerts, maintenance recalls, maximum generation actions, heavy-load voltage procedures, and transmission loading relief.
PJM reported a served peak load of 162,713 MW during the event. Accounting for emergency actions and customer load reductions, PJM estimated that unrestricted demand reached 168,158 MW, which the grid operator identified as an all-time unrestricted peak.
Joseph Bowring, president of Monitoring Analytics, PJM’s Independent Market Monitor, characterized the warnings as “precautionary.”
“[The] actual extent of potential reliability contribution is not well known, in my opinion,” Bowring told Data Center Knowledge. “The significance is that PJM was getting very close to a shortage of primary reserves.”
Former Federal Energy Regulatory Commission (FERC) Chairman Neil Chatterjee said the episode reflects an evolving posture toward customer-owned generation. “This is not extraordinary and should not be considered rare from this point forward,” he told Data Center Knowledge. “This is more a bellwether, ‘canary in the substation,’ if you will.”
Chatterjee added that grid operators and utilities are both programmatically and reactively relying on dispatchable distributed energy resources to mitigate grid stress and larger power emergencies. As those resources continue proving their value, he said, their use is likely to become more common.
No Dispatch Ordered
In response to questions from Data Center Knowledge, PJM confirmed that it did not issue an Emergency Use of Backup Generators Action during the July 2–3 period. “No such action was required,” a PJM spokesperson said. The operator said no backup generators were operated in response to the warnings and no large-load backup generation was dispatched under the emergency procedure.
PJM also clarified that the warning was issued to the Dominion control zone.
While all PJM transmission owners reported the amount of large-load demand that could be transferred to backup generation within 15 minutes, PJM declined to disclose the total megawatts available. The operator said it does not collect data on the number of eligible facilities, nor does it estimate how much of the available backup generation comes from data centers versus other large commercial and industrial customers.
PJM said it currently follows the definition of “large loads” established in the DOE’s Section 202(c) order. The 50 MW threshold discussed in the stakeholder process has not yet been formally adopted into PJM’s governing documents.
A New Reliability Tool Among Many
The Operating Committee presentation shows that PJM relied on numerous reliability tools during the heat wave. Demand response programs reduced load by approximately 6,113 MW on July 2 and by 5,037 MW on July 3.
The DOE emergency emissions order covered 51 generating plants, 594 generating units, and approximately 20.4 GW of capacity. PJM reported that 17 plants, representing 94 generating units and about 3.25 GW of capacity, operated beyond normal emissions limits for a combined 1,107 operating hours.
PJM also reported three Shared Reserve Events, two Maximum Generation Emergency/Load Management Alerts, two NERC Energy Emergency Alert Level 1 declarations, and five Hot Weather Alerts. On June 29, PJM approved five shortage cases after “solar dropped out faster than steam could ramp up.”
Although PJM never called on large-load customers to switch to backup generation, the July heat wave marked the first operational use of the warning process, offering an early indication of how the grid operator may manage large flexible loads as electricity demand from data centers continues to grow.

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