Major power grids serving much of the eastern and central United States came under renewed pressure this week as high temperatures, power plant outages, heavy air-conditioning demand, and transmission constraints tightened electricity supplies.
The Midcontinent Independent System Operator, or MISO, issued an Energy Emergency Alert 2 on July 15 across a region covering parts of 15 states. MISO cited above-normal temperatures, generating plant outages, and electricity demand that exceeded expectations.
PJM Interconnection, the country’s largest regional grid operator, also issued a series of warnings as heat pushed demand close to record levels. PJM serves approximately 67 million people across 13 states and the District of Columbia.
The simultaneous pressure on both systems makes the current situation more significant than a short-lived alert affecting one isolated region.
MISO Declares an Energy Emergency
MISO’s July 15 emergency alert followed a combination of generation losses and heavier-than-expected electricity use.
The grid operator manages power flows across a broad area stretching from the Upper Midwest into the South. High temperatures across that territory drove air conditioners harder at the same time that several power plants could not supply their expected output.
MISO’s own operating data notes that committed generating capacity does not necessarily include electricity that transmission congestion prevents the system from delivering where operators need it. That distinction becomes important during widespread heat because available electricity in one area may not reach another area with greater demand.
Wholesale electricity prices reflected the tightening conditions. Prices climbed above $900 per megawatt-hour at MISO’s Michigan hub and remained near $600 per megawatt-hour in Illinois, Indiana, and Minnesota, according to Reuters and MISO pricing data.
Wholesale price spikes do not immediately translate into an identical increase on a household bill. They do show that grid operators must pay much more than normal to obtain the next available unit of electricity.
PJM Faces Heat and Transmission Congestion
PJM issued warnings concerning low voltage and heavy loads on transmission lines on July 15. The grid operator expected demand to reach approximately 164.1 gigawatts during the evening peak, close to its record of 168.2 gigawatts set on July 2.
Transmission congestion created particular pressure around northern Virginia, which contains the world’s largest concentration of data centers.
PJM wholesale prices rose from around $30 per megawatt-hour earlier in the day to more than $300 as temperatures and electricity use increased.
Those prices highlight a problem that extends beyond the amount of electricity generated across the entire PJM region. The system also needs enough transmission capacity to move that electricity into high-demand areas.
A power plant hundreds of miles away offers limited help when overloaded transmission lines cannot carry its output to the communities, businesses, and data centers that need it.
Data Center Demand Is Reducing PJM’s Margin
Heat triggered the immediate strain, but PJM also faces a longer-term supply problem.
Results from its latest capacity auction showed that electricity demand continues to rise faster than available supply. The auction reached its temporary price cap of approximately $325 per megawatt-day and still fell about 6.8 gigawatts short of PJM’s reliability target.
PJM uses the capacity market to secure enough future generation for the system’s highest-demand periods. Falling short does not guarantee blackouts, but it leaves operators with a smaller buffer when extreme temperatures, power plant failures, or transmission problems occur together.
Data centers now drive much of PJM’s expected demand growth. Their large and relatively constant loads have developed faster than utilities can build new power plants and transmission infrastructure.
The latest auction would have produced prices of more than $554 per megawatt-day across most of PJM without the temporary cap. Prices in the ComEd area of Illinois would have exceeded $775. Capacity costs eventually form part of electricity bills paid by households and businesses.
DOE Emergency Orders Add Another Layer of Protection
The Department of Energy has issued several emergency orders this summer to give PJM more options during severe grid conditions.
Orders issued on June 30 allowed PJM to dispatch specified generating units when needed and to direct backup generators at data centers and other large facilities to operate as a last resort before or during the highest Energy Emergency Alert level.
DOE issued another order following a PJM request on July 13. That order took effect late on July 14 and remains effective through July 21. It again authorizes PJM to call on backup generation at large-load facilities as a final measure before an Energy Emergency Alert 3, the stage at which controlled service interruptions may become necessary.
Other DOE orders have kept generating units available in both PJM and MISO territory, including plants in Pennsylvania, Maryland, Indiana, and Michigan.
These measures do not mean widespread blackouts are imminent. They show that grid operators and federal officials consider the available operating margin narrow enough to justify exceptional precautions.
Why Pressure Across Multiple Grids Matters
Regional grid operators often import electricity from neighboring systems when local supplies tighten.
That support becomes harder to obtain when heat affects several regions simultaneously. MISO may have less surplus electricity available for PJM, while PJM may have less capacity available to support neighboring areas.
Power plant outages compound the problem. Transmission congestion can then trap available generation on the wrong side of an overloaded power line.
The result may not be a nationwide outage. Local utilities could face a higher risk of equipment failures, voltage problems, short interruptions, or controlled outages in areas where demand exceeds the power that local infrastructure can deliver.
A Practical Household Response
Households in affected regions should treat the current alerts as a reason to check existing plans rather than a reason to panic.
Residents who rely on air conditioning should identify a backup cooling option and know where they could go if indoor temperatures become unsafe. Heat can turn even a relatively short outage into a medical emergency, especially for older adults, young children, and people with chronic health conditions.
Charge battery banks and portable power stations before the evening demand peak. Confirm how long essential medical devices can run on backup power and review medical preparedness for preppers for longer disruptions.
Generator owners should check fuel, oil, extension cords, and carbon monoxide detectors. Generators must always operate outdoors and well away from doors, windows, and vents.
Freezers and refrigerators can usually protect food during a short outage when people keep the doors closed. A thermometer provides a clearer indication of food safety than guesswork. Longer-term storage planning belongs in a broader prepper food storage strategy.
Stored drinking water also matters because extended outages can disrupt private wells, pumps, and some municipal systems. Households can review water storage for preppers before the next alert arrives.
A complete response does not require buying new equipment every time temperatures rise. Sensible bugging in essentials, and a realistic grid down survival plan provide a good foundation.
PJM and MISO have so far relied on emergency procedures, additional generation, and higher-cost electricity to keep supply and demand balanced. The current episode nevertheless shows how extreme heat, unavailable power plants, constrained transmission, and rapidly growing industrial demand can place several major grid regions under pressure at the same time.
Prepper's Paradigm is a participant in the Amazon Services LLC Associates Program and other affiliate programs. This means we may earn a commission if you make a purchase through links on our site, at no extra cost to you. For more details, please see our disclosure notice.
