A powerful heat wave is pushing electricity systems across parts of the United States toward their limits, with millions of households and businesses in the Midwest and Mid-Atlantic facing a heightened risk of power disruptions as temperatures climb and demand for air conditioning surges.
The pressure is particularly acute across the PJM Interconnection, the largest electricity grid network in the United States, which serves about 67 million people across an area stretching from the Chicago region to Washington, D.C. Federal energy authorities have taken emergency measures to strengthen the system ahead of what is expected to be a period of exceptionally high demand.
US Energy Secretary Chris Wright late Tuesday authorised PJM to bring additional backup power resources into operation as a precaution against possible instability on the grid. The emergency authorisation is intended to provide the network with additional capacity before conditions deteriorate to the point where more severe measures, including controlled power interruptions, become necessary.
The Department of Energy said the action was designed to help PJM maintain stability across the Mid-Atlantic system and reduce the possibility of widespread blackouts during the heat wave.
Wright stressed that maintaining dependable electricity supplies during extreme weather remains a priority, particularly when households and businesses rely heavily on cooling systems to cope with high temperatures.
The emergency intervention comes as weather forecasts point to temperatures exceeding 90 degrees Fahrenheit, or about 32 degrees Celsius, in several major cities during periods when electricity consumption is expected to be at its highest. St. Louis, Chicago and Washington, D.C., are among the urban areas facing significant heat as demand for cooling increases.
Extreme heat can place an unusual combination of pressures on electricity systems. As temperatures rise, households and commercial properties typically increase their use of air conditioners, pushing demand higher precisely when power infrastructure and generating equipment are also operating under stressful conditions.
PJM has therefore moved to identify additional generating resources that could be brought online if necessary. Under a maximum-generation emergency alert issued early Wednesday, the grid operator instructed power plants that are currently undergoing scheduled maintenance to provide information on how quickly they could return to service.
The request is intended to give system operators a clearer picture of how much generation could become available if electricity demand rises beyond available operating capacity. Plants that are offline for maintenance can represent a potentially important reserve during periods when the grid is under exceptional pressure, provided they can safely resume generation.
The developments within PJM are part of a broader pattern of concern across US electricity markets as the heat wave drives demand upward. Another major grid operator, the Midcontinent Independent System Operator, or MISO, is also preparing for exceptionally high consumption.
MISO operates the electricity network serving 15 states and has projected that demand could approach 121 gigawatts during the current period of extreme heat. That figure would bring consumption close to the operator’s historical peak of 127.1 gigawatts.
The projected demand has prompted MISO to focus closely on its available operating margins. When demand rises sharply, grid operators must maintain sufficient reserves to respond to unexpected problems, including generator failures, transmission restrictions and congestion on electricity lines.
MISO has expanded its reserve capacity as part of its response, seeking to ensure that an unexpected loss of generation or transmission capacity does not immediately create a supply shortfall.
The emphasis on reserves reflects the difficulty of managing an electricity network during extreme weather. Grid operators must continuously balance electricity production with consumption, while also maintaining enough additional capacity to deal with sudden changes in either supply or demand.
Even a relatively small disruption can become more consequential when operating margins are already tight. A generator unexpectedly going offline or congestion limiting the movement of electricity between areas can reduce the amount of power available to locations experiencing the highest demand.
That is why operators across the affected regions have been preparing before the heat reaches its peak. Emergency authorisations, reserve generation and requests for additional information from power plants are designed to give grid managers more options if demand continues to climb.
The federal government intervention involving PJM represents one of the measures available to authorities before the system reaches a more serious emergency stage. A level 3 energy emergency alert can precede rotating outages, in which electricity service is deliberately interrupted in selected areas to prevent a broader collapse of the grid.
Such controlled outages are generally intended as a last-resort mechanism for keeping an electricity system stable when available generation is insufficient to meet demand. The steps being taken now are aimed at reducing the likelihood that operators will have to reach that stage.
Electricity distributors are also turning to consumers for assistance, asking households and businesses to reduce unnecessary consumption during periods of peak demand.
In Missouri’s rural Ozark region, Howell-Oregon Electric Cooperative has encouraged customers to take simple steps to reduce their electricity use. Among the recommendations are unplugging electronics that are not being used and raising thermostat settings to reduce the amount of electricity required for air conditioning.
Such conservation measures can have a collective effect when large numbers of customers participate at the same time. Reducing electricity consumption during the busiest hours can ease pressure on local distribution systems and contribute to maintaining wider grid stability.
The request is particularly relevant because air conditioning can account for a substantial increase in electricity use during periods of extreme heat. Even modest adjustments to cooling settings across thousands of homes and businesses can help reduce peak demand.
For grid operators, however, consumer conservation is only one part of the response. Maintaining adequate generation, ensuring transmission lines remain available and keeping sufficient reserves on hand are all necessary when temperatures create extraordinary demand.
The situation across PJM and MISO illustrates how quickly weather conditions can become an electricity reliability issue. The challenge is not simply whether there is enough generating capacity over an entire day, but whether sufficient electricity can be delivered at the precise hours when demand reaches its highest point.
The current warnings are therefore focused on peak periods rather than electricity consumption alone. Cities experiencing temperatures above 90 degrees Fahrenheit are likely to see residents and businesses increase cooling use at the same time, creating concentrated demand across urban and regional networks.
PJM’s request for information from plants undergoing maintenance and the federal authorisation to use backup resources indicate that authorities are preparing for that possibility rather than waiting for shortages to emerge.
Meanwhile, MISO’s preparations show that concerns extend beyond the PJM territory. With projected demand approaching 121 gigawatts, the operator is working with narrower margins and additional reserves to provide a buffer against unexpected events.
The heat wave has consequently placed grid reliability at the centre of attention across several major US electricity markets. Federal officials, regional grid operators and local utilities are all taking steps to limit the possibility that extreme temperatures will translate into widespread electricity interruptions.
For consumers, the immediate message is to reduce unnecessary electricity use during peak periods where possible, particularly as air conditioners operate for longer periods. Utilities have also stressed practical conservation measures that can lower household demand without eliminating essential cooling.
The coming period will test the ability of the affected electricity networks to manage a combination of high temperatures, surging cooling demand and the possibility of unexpected equipment or transmission problems.
While emergency measures have been activated as a precaution, the objective remains to keep electricity flowing without reaching the stage where rotating outages are required. The federal government and grid operators are therefore relying on additional generation, expanded reserves, plant availability and consumer conservation to help absorb the pressure created by the heat wave.
For millions of Americans across the Midwest and Mid-Atlantic, the effectiveness of those measures could determine whether the current surge in temperatures results primarily in higher electricity demand or develops into a wider power reliability crisis.
Heat Wave Puts US Power Grid Under Pressure as Blackout Risk Rises Across Midwest, Mid-Atlantic
A woman jogs by power lines in Mountain View, California, U.S., August 17, 2022. REUTERS/Carlos Barria/File Photo/Reuters
