BOSTON: Pennsylvania-New Jersey-Maryland Interconnection (PJM), the largest US electric grid operator, has detailed price spikes and warnings of massive transmission line congestion as it braces for record-breaking demand driven by a heatwave ahead of July 4 celebrations.
Spot wholesale electricity prices on Wednesday surged to more than US$600 per megawatt hour (MWh) in PJM’s Virginia zone, home to the world’s largest collection of data centres.
Earlier in the day, prices were about US$40 per MWh before temperatures soared towards 37.8°C.
Demand on the grid topped 160 gigawatts (GW) on Wednesday afternoon, approaching an all-time high.
PJM’s record of 165.5GW was expected to be broken yesterday evening, according to PJM forecast data.
PJM serves 67 million people in the Mid-Atlantic, South and Washington, DC areas.
Even before this week’s heatwave, PJM had been straining to overhaul a system pushed to the brink by surging energy consumption by data centres and electric vehicles.
The grid operator on Wednesday afternoon issued an alert asking power plants to maximise their output and to review whether any generators offline can be fired up for service.
PJM’s low-voltage alert signalled that the risk of rotating outages is higher as voltage levels on transmission lines weaken.
The grid operator also has forewarned power plants to bring generators out of maintenance so they can be ready to meet surging demand.
Gridraven chief executive officer Georg Rute said extreme heat, low wind and surging demand are coinciding at a time when transmission lines have the least margin for safety.
That is contributing to spikes in electricity prices, as the cost of moving power rises amid heavy congestion.
Temperatures this week are forecast to hover around 37.8°C from Boston to Washington, near Northern Virginia’s vast data centre hub, driving a surge in air-conditioning demand that will further strain PJM and other regional power grids.
New York ISO (NYISO), the grid operator for New York state, asked electricity customers to moderate their use of air conditioning and major appliances.
NYISO was preparing yesterday demand of more than 32GW, just shy of the record set in 2013 of 34GW.
PJM’s biggest test will come when grid demand is expected to be 166.3 gigawatts. That would break an all-time demand record set 20 years ago, according to PJM’s latest forecast.
To meet unexpected shortages, PJM reported 18GW of reserve power resources that can be brought online within 30 minutes.
Spot electricity prices was expected to spike to more than US$1,000 per MWh on Wednesday evening as PJM operators manage congested power lines around Virginia’s data centre hub and dispatch expensive power plants mainly fuelled by gas and coal to meet the day’s highest electricity consumption. Coal plant generation this week has produced up to 22% of PJM’s electricity supply, with output approaching 28GW.
That’s about 75% higher than the average so far in 2026, according to PJM generation data.
In the Midwest, another record for electricity demand could be broken as early as Wednesday evening.
Forecasts by the Midcontinent Independent System Operator, the regional grid operator for 15 US states in the Midwest and the South, have indicated that the demand record of 127.1GW could fall.
The mounting strain across multiple US grids underscores how extreme weather, electrification and the rapid expansion of data‑centre infrastructure are converging faster than transmission upgrades can keep pace.
At the federal level, regulators and grid planners are warning that this summer’s strain is a preview of deeper structural challenges ahead, as electrification accelerates and data centre clusters multiply faster than transmission can be built.
PJM and other operators have urged faster permitting for new lines, more flexible market rules and expanded reserve capacity to prevent future bottlenecks.
Energy analysts said the coming weeks will serve as a critical stress test for operators already juggling ageing lines, volatile generation patterns and unprecedented peak loads.
As utilities brace for more heatwaves through the summer, PJM and its counterparts face a defining challenge: keeping the lights on while navigating a structural shift in how – and how much – America now consumes electricity. — Reuters
