Extreme Heat Risks Summer Power Shortages, Warns Largest US Grid

(Bloomberg) -- PJM Interconnection LLC, the largest US electric grid serving about 20% of Americans from the Midwest to East Coast, warned that extreme heat this summer could trigger supply shortages for the first time. 

While PJM expects to have enough power supply to meet typical summer demand, “available generation capacity may fall short of required reserves” under severe conditions that lift demand as high as 166 gigawatts, the grid operator said Friday. Such an extreme scenario would topple the 2006 record of 165.6 gigawatts. One megawatt is typically enough to power 800 homes in PJM. 

PJM expects this summer to be hotter than normal, especially in the Eastern seaboard states, with demand rising 0.9% to peak at 154.1 gigawatts. The grid operator noted it has another 7.9 gigawatts of spare supplies available through demand-response programs, which compel enrolled commercial, industrial and even household consumers to curtail usage to keep the grid stable during emergencies. 

While it’s impossible to predict the likelihood of an extreme scenario, PJM’s warning underscores the demand constraints of a grid that was recently flush with supply. 

“PJM continues to voice concerns about the supply and demand imbalance driven by generator retirements and the slow build of new resources in the face of accelerating demand growth,” the statement said. 

(Updates with 2025 summer peak forecast in third paragraph.)

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