The North American Electric Reliability Corp. is warning of potential energy supply shortfalls in parts of the U.S. this summer during periods of extreme weather amid climbing electricity demand and a changing resource mix.
The warnings were part of NERC’s 2025 Summer Reliability Assessment released May 14, which evaluated generation resource and transmission system adequacy for June through September.
All areas studied by NERC are expected to have adequate resources for normal summer peak load conditions. But several regions are at risk of electricity supply shortfalls during periods of more extreme summer weather, including New England, parts of the Midwest, the Southwest Power Pool and Texas.
According to the report, weather services anticipate above-average temperatures across much of North America this summer and below-average precipitation in the Northwest and Midwest.
Total peak electricity demand for the areas that NERC assesses has risen by over 10 gigawatts since last summer, more than double the previous year-to-year increase. At the same time, more than 7.4 GW of generator capacity has retired or become inactive for the upcoming summer, most of it natural gas- and coal-fired generation.
Those losses are offset by over 40 GW in on-peak capacity gains from new solar, battery and wind installations, but “operators in many parts of the [bulk power system] face challenges in meeting higher demand this summer with a resource mix that, in general, has less flexibility and more variability,” the report noted.
“ As demand expands, grid planners and operators are doing more than ever, but they’re doing it under tighter reserve margins,” said John Moura, NERC’s director of reliability assessment and performance analysis, in a May 14 webinar on the report. “While we’re adding a lot more resources—solar, batteries and other emerging technologies—the pace and performance of that buildout doesn’t yet fully align with the reliability needs of a rapidly electrifying economy.”
To address potential electricity supply shortfalls, NERC encouraged transmission owners and relevant grid authorities to review their operating plans and operate conservatively to ensure adequate resource availability.
The report also urged grid operators to be prepared for the potential of inverter-based resources including solar photovoltaic and battery capacity to unexpectedly trip during grid disturbances, such as short circuits or line breaks.
“Once again, NERC identifies continuing threats to the electric grid that leave a large area of the country vulnerable to power supply disruptions during periods of extreme summer conditions,” said NRECA CEO Jim Matheson. “Demand is surging, supply isn’t keeping up, and the resources being added to the grid aren’t as flexible and reliable as the always available generation they’re replacing.
“Now more than ever, we need smart energy policies that prioritize reliability, affordability and put American consumers first. We look forward to continuing to work with policymakers to meet this challenge and keep the lights on across the nation.”
Mid-Atlantic grid operator PJM Interconnection has also warned of potential reliability issues in the event of higher-than-normal demand scenarios this summer. On May 9, PJM said it may need to reduce loads in the region by relying on contracted demand response resources if demand hits record levels. Demand response pays customers to reduce their electricity use in times of system emergencies.
PJM’s summer assessment is the grid operator’s first where it sees available generation capacity in the area possibly falling short of required reserves in an extreme planning scenario.
NERC said its summer findings are consistent with risks and issues that it observed in its latest Long-Term Reliability Assessment, released in December.
That report said that over half of North America is at risk of energy shortfalls in the next 10 years amid surging electricity demand and thermal plant retirements. NERC projected that capacity additions to the bulk power system in the next decade will fall short of demand growth.
Molly Christian is a staff writer for NRECA.