Dark smoke rose above a Virginia data center as a heat wave pushed the power grid close to its limits

Smoke rises from a Digital Realty data center in Northern Virginia on July 3, 2026. Bobby Chahal Energy regulators warned data centers could be cut off as a heat wave swept the mid-Atlantic states. PJM, which runs the regional grid, said "demand response" kept power consumption manageable. Dark smoke was seen rising from a Virginia data center. Other big loads also ran diesel generators. Ashburn, Virginia, is in the heart of America's "data center alley." Over the July 4 weekend, diesel generators at a Digital Realty data center switched on as temperatures spiked. Dark smoke floated above ACC9, one of dozens of data centers clustered in Ashburn and nearby cities, according to a video and photos from July 3 seen by Business Insider. The company said it turned on generators as part of a program run by the electrical grid operator, PJM Interconnection, to reduce the load on the grid during times of peak demand. In recent years, unprecedented volumes of cash have been pumped into America's data center buildout and into the construction of new power plants and transmission lines. A Business Insider analysis found that 176 new data centers were permitted in 2025, which could together require enough electricity to power millions of homes. The growing footprint of such data centers has touched off debates about their role in rising energy costs . It also has some people worried about the environmental impact of burning fossil fuels to generate backup power, particularly on days like July 3, when the high was 102 degrees in Ashburn. "We're talking about normalizing running our grid and protecting it with 18th-century electricity," said Elena Schlossberg, a northern Virginia activist. "That is what diesel fuel is." Disaster averted Data centers are a small minority — around 5% — of those enrolled in PJM's demand-response programs, according to information published by the grid operator, which coordinates power generators, large loads, and utilities that supply power to roughl