The North American Electric Reliability Corporation (NERC) said on Thursday that the likelihood of power outages in the United States is increasing, driven by a changing generation mix and rapidly expanding winter electricity demand. In its long-term assessment, NERC pointed to several large regions - the Mid-Atlantic, Midwest, Northeast and Texas - as potentially facing high risk of supply shortfalls before the end of the decade.
The assessment comes after a winter storm earlier this week that at one point left more than 1 million U.S. homes and businesses without power, as electrical systems contended with high winds and extended periods of freezing temperatures. NERC said the coldest months will become a larger operational challenge for the bulk power system.
A key factor cited by the regulator is the rapid increase in solar generation, which generally produces more energy in the sunny summer months than during winter. At the same time, the electrification of heating systems is shifting demand patterns toward colder months, increasing winter peaks. NERC noted that projected electricity demand across the U.S. and Canada over the next decade will exceed peak demand levels observed during the past 20 years.
Specifically, NERC's outlook expects winter peak demand to rise by 245 gigawatts over the upcoming decade. The report provides context for that scale by noting that one gigawatt is enough to power roughly 750,000 homes. While historically U.S. electricity demand has tended to peak in the summer, growth in winter demand is now outpacing summer growth as heating electrifies. NERC also said that overall demand increases are being driven in large part by data centers.
As demand grows, power reserve margins are projected to shrink in many regions because new supply additions are not keeping pace. NERC's assessment, which uses data and inputs up to mid-2025 and is described by the agency as evolving, highlights stark changes in reserve margins in major grids.
In PJM Interconnection - the largest regional grid operator in North America - the supply reserve margin is expected to decline to about 14% in 2030, down from nearly 30% this year, based on the assessment's data. On the Midwest grid operated by MISO, reserves are forecast to fall to roughly 4% in 2030 from about 11% in the current year.
Those shifts, according to NERC, raise the prospect of tighter operating conditions during winter months and a greater potential for shortfalls if the system encounters extreme weather or other stressing events. The assessment underscores the interplay between changes in generation characteristics and evolving demand drivers, and the effect those trends are having on regional reserve margins and reliability risk.
Summary
NERC's long-term assessment warns that wintertime reliability risks are growing in the U.S. and Canada as solar additions and heating electrification push peak demand into colder months. The Mid-Atlantic, Midwest, Northeast and Texas regions are identified as areas that could face high risk of supply shortfalls before the decade's end, while reserve margins in major grids such as PJM and MISO are projected to shrink substantially.
Key points
- Winter peak demand is projected to increase by 245 gigawatts over the next decade, with one gigawatt roughly equivalent to the power needs of about 750,000 homes.
- Rapid additions of solar, which produce more in summer, combined with increased electrification of heating, are shifting peak demand toward winter months.
- Reserve margins are expected to decline in several regions - PJM's reserve margin could fall to about 14% in 2030 from nearly 30% this year; MISO's could decline to about 4% from 11%.
Risks and uncertainties
- Higher risk of winter power outages in the Mid-Atlantic, Midwest, Northeast and Texas if reserve margins tighten and extreme weather or other stressors occur - pertinent for utilities, grid operators and residential heating markets.
- Shrinking reserve margins in major regional grids may constrain operational flexibility and increase vulnerability to supply shortfalls - relevant for energy markets, power generators and large electricity consumers such as data centers.
- Dependence on resources that produce more in summer (solar) while demand grows in winter could exacerbate seasonal imbalances unless new winter-capable supply or other measures are deployed - important for generation planning and capacity markets.