PJM grid operator issued emergency backup-generator warnings during July heat wave, signaling demand surge across regional wholesale market.

PJM issued its first "Transmission Security – Emergency Use of Backup-Generator Warning" on July 2 in the Mid-Atlantic and Dominion regions, and again on July 3 in Dominion, as the grid operator approached record demand during a severe heat wave. The alerts followed a US Department of Energy (DOE) emergency order under Section 202(c) that authorized large-load customers to shift to on-site generation to protect grid reliability. However, PJM ultimately did not call on any large-load customers to operate their backup generators, characterizing the warnings as precautionary.

PJM added the emergency backup-generator procedures to its operating manuals this year amid growing reliability concerns. 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. While the procedure was not fully activated, the July episode provided the first real-world test of this new reliability tool designed to tap into customer-owned backup generation during grid emergencies.

The warnings were issued as PJM deployed multiple reliability measures simultaneously. The grid operator 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—an all-time unrestricted peak. Demand response programs alone reduced load by approximately 6,113 MW on July 2 and 5,037 MW on July 3. The DOE emergency emissions order covered 51 generating plants, 594 units, and approximately 20.4 GW of capacity; 17 plants representing 94 units and about 3.25 GW operated beyond normal emissions limits for a combined 1,107 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 generation dropped faster than steam plants could ramp up.

Joseph Bowring, president of Monitoring Analytics and PJM's Independent Market Monitor, characterized the warnings as precautionary, noting that "the actual extent of potential reliability contribution is not well known." He emphasized that "PJM was getting very close to a shortage of primary reserves."

Former Federal Energy Regulatory Commission Chairman Neil Chatterjee offered broader perspective on the episode, stating: "This is not extraordinary and should not be considered rare from this point forward. This is more a bellwether, 'canary in the substation,' if you will." Chatterjee observed that grid operators and utilities are increasingly relying on dispatchable distributed energy resources to mitigate grid stress and larger power emergencies, and predicted that as these resources continue proving their value, their use will become more common.

PJM declined to disclose the total megawatts of large-load backup generation available across its transmission owners, nor does it collect data on the number of eligible facilities or estimate what proportion comes from data centers versus other large commercial and industrial customers. The operator currently follows the DOE's Section 202(c) definition of "large loads," though the 50 MW threshold discussed in stakeholder processes has not yet been formally adopted into PJM's governing documents.