America's biggest power grid just told data centers it can cut their power off - Startup Fortune

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America's biggest power grid just told data centers it can cut their power off

PJM Interconnection received emergency DOE authority in June 2026 to curtail data centers mid-operation to prevent blackouts, forcing 50MW-plus facilities onto backup generators within 15 minutes. With summer peak demand projected to rise 58 percent by 2046 and capacity market costs up $23 billion, power availability is becoming the binding constraint on AI scaling that chips never were.

Ron Patel

Jul 28, 2026 · 10:02 PM ·<br>5 min read<br>1.2K reads

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PJM did not actually cut off data centers during the July heat wave, but it came close enough to change the conversation. If your AI plan assumes power is always there, you need to update the model.

The U.S. Department of Energy gave PJM Interconnection emergency authority this summer to tell large electricity users with backup generators, including data centers, to get off the grid before blackouts hit homes and businesses. That is a remarkable sentence for the largest power market in America. PJM serves about 67 million people across 13 states and Washington, and the order put data centers inside the emergency playbook, not outside it.

The detail PJM later supplied is important. On July 2, as demand approached record levels, the grid operator issued an emergency warning to prepare some transmission owners and utilities for the possible curtailment of data centers and other large loads in the BGE, PEPCO and Dominion zones. PJM said the final step was not needed. Service was not affected. No large-load backup generation was dispatched under that procedure, according to PJM's July 3 hot weather update and later reporting by Data Center Knowledge.

The warning was enough.

If you run a startup buying compute from a hyperscaler in Northern Virginia, you don't need a blackout to learn something from this. You need to notice that grid operators are now treating power-hungry compute as flexible demand in an emergency. Cloud contracts talk about uptime, regions, availability zones and service credits. The power system underneath them talks about heat, reserve margins, transmission constraints and generators tripping offline at 5 p.m.

The grid came closer than the headline suggests

PJM's preliminary July 2 peak was about 162,700 megawatts between 5 p.m. and 6 p.m., but the operator said that figure was suppressed by roughly 6,000 megawatts of demand response. S&P Global reported that PJM later set a new all-time peak-load record of 168,158 megawatts during the heat wave, above the old 2006 summer peak of roughly 165,600 megawatts. That is not abstract pressure. That is the grid using nearly every lever it had.

The Department of Energy order issued June 30 authorized PJM, working with transmission owners and distribution companies, to direct backup generation resources to operate as a last resort before an Energy Emergency Alert 3 or during one. DOE said the orders were tied to forecast hot weather and the risk of blackout conditions. PJM also received authority to dispatch specified generating units and later sought extensions as the heat persisted.

This is not the first time the issue appeared. DOE issued an earlier Section 202(c) order on May 18 after PJM asked for emergency authority tied to backup generation at data centers and other major facilities. E&E News reported at the time that PJM wanted the ability to direct data center customers with backup generation to rely on those facilities in order to avoid rolling blackouts. The summer order made the risk easier to see.

Power is the bottleneck.

PJM's 2026 long-term load forecast projects summer peak demand growth averaging 3.6 percent a year over the next decade, compared with 0.3 percent in its 2021 forecast. E&E News noted in January that PJM trimmed some near-term AI-driven demand estimates, including about 2,500 megawatts from the 2026 summer peak forecast, but the direction did not change. The forecast still points to a region where data center demand is growing much faster than new firm supply.

Northern Virginia is where the pressure shows first

The problem is local. Loudoun County's Data Center Alley, with nearby growth in Prince William and Fairfax counties,...