PJM, the largest U.S. power grid operator, said it ordered generators to run at maximum output and bring idle power plants online immediately on Thursday evening, as it faced escalating stress ​from a heat dome.

PJM's orders, detailed on its emergency procedures website, were aimed at ​preserving reliability as it sought to maintain power on a grid serving 67 ⁠million people across the Mid-Atlantic, South and Washington, D.C., regions and the world's largest concentration ​of data centers.

Even before this week's heat wave that sent temperatures soaring toward 100 degrees Fahrenheit (38 ​degrees Celsius), PJM had been straining to overhaul a system pushed to the brink by surging energy consumption by data centers and electric vehicles.