Scorching temperatures across the eastern United States put immense strain on the nation’s power grid Tuesday, forcing grid operators to take emergency measures to prevent widespread blackouts. With temperatures exceeding 100 degrees Fahrenheit, several regional grid operators faced critically low power generation margins. Transmission lines experienced congestion and overheating, leading to drastically inflated wholesale electricity prices. New York City saw prices surge to nearly $2,400 per megawatt hour (MWh), while Long Island’s wholesale rates climbed above $7,000 per MWh. New York ISO, responsible for managing the state’s electricity, issued warnings about potential emergency actions due to dwindling operating reserves.

PJM Interconnection, the largest U.S. power grid serving one in five Americans, implemented voluntary reduction programs, directing utilities to curtail electricity to customers. The grid operator repeatedly cautioned throughout the day as it struggled to maintain electricity flow through overheated transmission lines. Reduced output from gas-powered turbines, hampered by the extreme heat, further compounded the situation. ISO New England, covering a six-state area including Boston, witnessed spot wholesale prices spike past $1,500 per MWh, more than triple Monday’s peak during the initial phase of the heat wave.

To alleviate pressure on the grid, the U.S. Department of Energy mandated Duke Energy Carolina to maximize output from specific generating units in the southeastern U.S. ISO New England declared a “Power Caution” after unexpected generation losses left the region short of necessary resources. Grid operators are implementing strategies such as increasing imports from neighboring regions, delaying power plant maintenance, and activating standby units to bolster electricity supply. Duke Energy indicated potential electricity curtailments to avert outages, leading to notifications for wholesale customers to limit usage and reduce demand by up to 1,000 megawatts during peak hours. Boston reached a temperature of 100 degrees Fahrenheit, with electricity demand forecast to reach approximately 26,000 megawatts, below the record high set in 2006.