ASHBURN, Va. — A major data center in the heart of America's "Data Center Alley" belched dark diesel smoke into the air on July 3 as the regional electrical grid buckled under the strain of a severe mid-Atlantic heat wave. The site, owned by Digital Realty, fired up its on-site diesel generators as part of a load-reduction program ordered by the regional transmission organization, PJM Interconnection, to stabilize power delivery as temperatures reached 102 degrees.
Grid Operator Avoids Emergency Orders
PJM, which coordinates power for roughly one in five Americans, confirmed that its demand-response program was critical to keeping the grid manageable without resorting to mandatory emergency cutoffs. The program provides financial incentive payments to large industrial users, including the tech sector, for voluntarily taking their facilities off the primary grid during peak stress. While manufacturing constitutes 43% of this voluntary capacity, data centers represent a small but growing slice, approximately 5%, of enrolled participants. The grid operator confirmed that over a gigawatt's worth of stressed generation assets were run outside normal parameters during the holiday week.
The visible plume of smoke from the Digital Realty facility, known as ACC9, contained emissions from Caterpillar diesel generators—machines permitted for emergency use and rated at over 2 megawatts each. The company stated it was bound by permit restrictions on excessive generator runtime but declined to specify how many units operated that day. For residents of nearby Leesburg, the sight is becoming a recurrent feature of peak power demand. Local resident Bobby Chahal, who photographed the smoke, noted that his own residential electricity rates have climbed despite flat usage.
This reliance on distributed diesel generation, while a functional stopgap, spotlights a fundamental mismatch in America’s power infrastructure buildout. Wall Street and tech conglomerates have pumped unprecedented capital into constructing permitted data centers—176 were greenlit in 2025 alone—capable of collectively drawing electricity equivalent to the residential demand of millions of homes. Yet, this massive new load is being met with a grid protection strategy that falls back on localized fossil fuel combustion.
The economic benefits for localities are undeniable; Loudoun County’s data center tax haul hit $875 million in fiscal year 2024, effectively subsidizing household tax burdens. But the operational costs are externalized onto a transmission system not designed for such concentrated digital industry demand, ultimately manifesting as smoke signals over Ashburn and upward pressure on residential rates. For American workers paying the bill, the question is whether the infrastructure that powers modern commerce is becoming a liability for the domestic grid.