That’s because demands on the grid are growing at the same time the resources powering it are changing. Between broad-based electrification, manufacturing additions, and especially data center construction, electricity load growth is forecast to grow several percent a year through at least the end of the decade. At the same time, aging plants reliant on oil, gas, and coal are being retired (although planned retirements are slowing down), while new resources, largely solar and batteries, are often stuck in long interconnection queues — and, when they do come online, offer unique challenges to grid operators when demand is high.
For the previous 20 years, load growth has been relatively steady, Abe Silverman, a research scholar at Johns Hopkins, explained to me. “What’s different is that load is trending up,” he said. “When you’re buying and making arrangements for the summer, you have to aim a bit higher.”
Nowhere is the combined and uneven development of the grid’s supply and demand more evident than in PJM Interconnection, the country’s largest electricity market, spanning from Washington, D.C. to Chicago. The grid now has to serve new load in Virginia’s “data center alley,” while aggressive public policy promoting renewables in states such as Maryland and New Jersey has made planning more complicated thanks to the different energy generation and economic profiles of wind, solar, and batteries compared to gas and coal.
PJM hit peak load on Monday of just over 161,000 megawatts, within kissing distance of its all-time record of 165,500 megawatts and far north of last year’s high demand of 152,700, with load hitting at least 158,000 megawatts on Tuesday. Forecast high load this year was around 154,000 megawatts. Earlier this spring, PJM warned that for the first time, “available generation capacity may fall short of required reserves in an extreme planning scenario that would result in an all-time PJM peak load of more than 166,000 megawatts.”
While that extreme demand has not been seen on the grid during this present heat wave, we’re still early in the year. Typically, PJM’s demand peaks in July or even August; according to the consulting firm ICF, the last June peak was in 2014, while demand last year peaked in July. On Monday, real time prices got just over $3,000 a megawatt, and reached just over $1,800 on Tuesday.
“This is a big test. A lot of capacity has retired since 2006 and the resource mix has changed some,” Connor Waldoch, head of strategy at GridStatus, told me. While exact data on the resource mix over the past 20 years isn’t available, Waldoch said that many of the fossil fuel plants on the grid — including those that help set the price of electricity — are quite old.
PJM’s operators have issued a “maximum generation alert” that will extend to Wednesday, warning generators and transmission owners to defer or cancel maintenance so that “units stay online and continue to produce energy that is needed.”
PJM also issued a load management alert, a warning that PJM may call upon some 8,000 megawatts of electricity users who have been paid in advance to reduce demand when the grid calls for it. Already, some large users of electricity in Virginia have reduced their power demand as part of the program. There are historically around one or two uses of demand response per year in each of the electricity market’s 21 zones.
“Demand response is a real hero,” Silverman said.
Elsewhere in the hot zone, thousands of customers of the New York Independent Systems Operator lost or saw reduced power on Monday, along with over 100,000 customers affected by voltage reductions. On Tuesday, NYISO issued an “energy watch” meaning that “operating reserves are expected to be lower than normal,” and asking customers to reduce their power consumption.
Further north, oil and coal made up 10% of the fuel mix in ISO New England by Monday night, according to GridStatus data. The region has greatly expanded behind-the-meter solar generation since 2010, which as of 2 p.m. Monday was generating over 21% of the region’s power. But the grid as a whole hasn’t been able to keep up, thanks to a nationally anomalous shortage of gas capacity and still-insufficient battery storage. As the sun faded, so too did New England’s renewable generation.
“You don’t see coal very often in the New England fuel mix,” Waldoch told me. In fact, there is only one remaining coal plant in New England, which can typically power around 440,000 homes — though that’s based on normal electricity usage. On days like the past few, it may power far fewer.
Moving into Tuesday, Secretary of Energy Chris Wright invoked emergency authorities to allow Duke Energy in the Carolinas to run certain of its units “at their maximum generation output levels due to ongoing extreme weather conditions and to preserve the reliability of bulk electric power system.”
The strained grid and high prices come as grid operators question how effectively their current and planned generation capacity can meet future demand. These questions have become especially pressing in PJM, which last year shelled out billions of dollars in payments to largely fossil fuel generators in what’s known as a capacity auction. That’s already translating to higher costs for consumers — in some cases as high as 20%. But even that could be nothing compared to what’s coming.
“If you take the current conditions that PJM is dealing with right now and you add tens of gigawatts of data to center demand, they would be in trouble,” Pieter Mul, an energy and infrastructure advisor at PA Consulting, told me.
Right now, Mul said, PJM can muddle through. “It is all hands on deck. Our prices are quite high. They’ve invoked some various emergency conditions.” But that’s before all those data centers are even online. “It’s a 2026, ’27, and beyond question,” Mul said.
Today, however, “it’s mostly just very hot weather.”
