Data Center Alley is facing a climate test.
Searing temperatures this week could push energy demand to record levels on the mid-Atlantic’s electric grid, which fuels the country’s data center boom in Virginia.
To relieve some of the pressure, the Department of Energy granted permission Tuesday to the region’s grid operator, PJM Interconnection, to potentially force data centers to use backup diesel generators.
The move highlights the growing challenge of meeting rising electricity demand from data centers as the grid strains to keep the region cool during a period of extreme heat.
Many data centers rely on backup diesel generators, which release planet-warming emissions and lack air pollution controls designed to safeguard public health. The challenge is particularly acute in Virginia, the epicenter of the nation’s data center boom. State regulators have permitted more than 8,000 diesel generators at data centers in recent years, according to data from the state Department of Environmental Quality.
DOE’s order would allow data centers to run generators beyond limits for emissions that EPA has categorized as a “possible human carcinogen.”
Meeting higher electricity demand from air conditioning use during heat waves was already a challenge, said Kim Cobb, a climate scientist at Brown University. Adding data centers to the equation makes it harder.
“This is exactly what we expect in a warming world,” she said. “Even a modest increase in baseline temperature causes an exponential increase in heat extremes. You find yourself crossing these heat extremes much more frequently.”
Temperatures across the regional grid’s territory, which stretches from Washington to Chicago, are expected to soar Thursday. The National Weather Service said the heat index in Philadelphia and the nation’s capital could reach 110 degrees and 112 degrees, respectively. The heat wave is expected to fuel record-breaking temperatures through the weekend.
PJM recently updated its emergency procedures to account for the growth of data centers. Ordering the facilities to utilize backup generation is considered an option of last resort to prevent blackouts, coming only after urging consumers to limit their energy use. PJM’s request to DOE for the order is a first step in a process that would enable the grid operator to place data centers’ diesel generators on standby.
Aaron Tinjum, vice president of energy for the Data Center Coalition, an industry group, said facilities in the region “will work closely with utilities and grid operators, using backup power if directed and where appropriate to reduce strain on the grid and ensure Americans and first responders remain connected to the services they rely on.”
DOE has issued similar orders recently — in advance of Winter Storm Fern last winterand before a May heat wave this spring. PJM did not call on data centers to run their generators during those events — though forecasters predict more extreme conditions this week.
PJM has sufficient generating reserves to withstand intense summer heat waves, according to a recent assessment by the North American Electric Reliability Corp. But it is anticipating electricity demand far in excess of what it was expecting when it issued its summer reliability assessment in May.
Demand is projected to peak around 166 gigawatts on Thursday afternoon, exceeding the all-time record of 165 GW set in 2006. PJM predicted that summer demand would hit 156 GW this year, though it also included an “unlikely but plausible” scenario where electricity demand crests around 169 GW.
“It’s scary. It worries everyone when you see those kind of numbers,” said Abe Silverman, a former New Jersey utility regulator.
The grid should have enough generation to satisfy that power consumption, but the combination of higher temperatures, increased demand from data centers and a regulatory system straining to keep pace with skyrocketing electricity use is a worrisome dynamic, Silverman said.
The future looks even scarier. “The projections for data center loads dwarf the amount of data center load we have now,” he said.
Daniel Lockwood, a PJM spokesperson, attributed high demand estimates to the hot temperatures Thursday. He said the grid operator anticipates having enough generation to cover demand.
A DOE spokesperson did not respond to a request for comment. But Energy Secretary Chris Wright blamed the tight grid conditions on the Biden administration.
“We are reversing those failures and using every available tool ensuring Americans in the Mid-Atlantic have continued access to affordable, reliable, and secure energy to power and cool their homes,” Wright said in a statement accompanying the order on diesel generators.
Communities are caught in the middle. In Virginia, one-third of data centers are located within 500 feet of residential areas or schools, according to state auditors.
Some neighbors are bracing to see if their Fourth of July celebrations will be affected by unhealthy air.
“Nothing says life, liberty and the pursuit of happiness like breathing in diesel fumes,” said Elena Schlossberg, who runs a grassroots organization opposing data centers in Prince William County, which has 33 completed data centers and 31 more on the way.
No one wants the grid to collapse, she said, but she argued it’s not fair when neighborhoods pay for Virginia’s data center boom with their health.
“Either way, we are screwed,” Schlossberg said. “Either our lights go out or we get to breathe in this pollution.”
Data centers have turned to diesel generators during past heat waves. Last June, two facilities near Ashburn used diesel generators as temperatures climbed into the 90s. It’s unclear what prompted the move. It occurred after PJM had activated a demand-response program calling on electricity users to lower their consumption. But news reports later attributed the incident to a fire at a nearby substation. Dominion Power did not respond to questions about the incident.
It was an eye-opening experience for residents of Loudon County, who turned to Reddit to ask questions about dark gray plumes of smoke coming from the facilities.
“Last summer it was like, is everyone seeing what we are seeing?” said Ann Bennett, who oversees data center issues at the Sierra Club of Virginia. “This time around people are already emailing us asking if they should expect more diesel and how to protect themselves from the fumes during this heat wave.”
The number of diesel generators in the state has grown since then. Bennett, who has tracked DEQ permits for the machines, found that the agency allowed 3,790 additional diesel generators in 2025.
“This time, we are all anxiously anticipating what is going to happen, and we have thousands more generators to worry about,” she said.
