DOE Orders Data Centers on PJM Grid to Switch to Backup Generators Amid East Coast Heat Wave

On July 1, U.S. Energy Secretary Chris Wright approved a request from PJM Interconnection to let large data centers and other high-consumption facilities on the PJM grid temporarily disconnect from the grid and operate on on-site backup generators. The waiver, covering July 1-3 during an extreme Midwest and East Coast heat wave, aims to free grid capacity for residential air-conditioning.

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The heat wave has driven electricity demand for air conditioning to levels that strain the PJM Interconnection network. Data centers draw large power and contribute to peak load. The Department of Energy previously issued a similar waiver for Duke Energy in the Carolinas. About 35 GW of backup generation exists nationally, but the portion to be used is undisclosed.

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The order lets Duke Energy operate specified units at full capacity despite air-quality or permit limits, prioritizing reliable power. Secretary Wright said affordable, reliable, and secure electricity in the Duke Energy service area is essential and non-negotiable. The Department of Energy described the waiver as a temporary response to an acute, weather-driven demand spike.

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PennEnvironment warned that using diesel-powered backup generators could raise local air-pollution during the July 4 holiday weekend, exposing nearby residents to higher emissions. The group cited a May 2026 Environment America report questioning the appropriateness of permitting large electricity users to shift to diesel generators during grid stress, noting potential public-health risks.

PJM Data Center Waiver Raises Health Concerns in Heat WaveTechRadar

Sources concur on the waiver’s dates and purpose but differ on its impact. The DOE order cites 35 GW of national backup generation yet does not specify how much will be diverted from the grid. No data are given on projected emission changes or on the actual reduction in residential load, leaving the net benefit uncertain.

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• “The order authorizes Duke Energy to operate specified units up to their maximum generation output levels, notwithstanding air quality or other permit limitations arising under federal, state, or local law or regulation, or other applicable source of law,” — DOE directive

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• “Maintaining affordable, reliable, and secure power in the Duke Energy service territory is non-negotiable,” — Chris Wright, U.S. Energy Secretary

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• “As the nation celebrates its 250th anniversary this weekend, Americans celebrating this momentous occasion shouldn’t be forced to choose between going outside to enjoy the holiday with friends and family, and facing the risk of dirty diesel generators belching pollution from nearby data centers,” — David Masur, Executive Director, PennEnvironment

PJM Data Center Waiver Raises Health Concerns in Heat Wave

The waiver remains in effect through July 3, after which grid operators will reassess capacity and emissions data. Monitoring of air-quality impacts and grid reliability is expected to inform any further emergency measures should the heat wave persist or recur.

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