Electricity prices soar as US regional grids wobble from extreme heat

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4 days ago

By Tim McLaughlin and Timothy Gardner
BOSTON (Reuters) -U.S. regional electric grid operators scrambled to avoid rotating blackouts on Tuesday, preserving razor-thin power generation margins as temperatures in the eastern half of the country soared past 100 degrees Fahrenheit (38 degrees Celsius).
Jammed and overheated transmission lines caused congestion and lifted wholesale electricity prices in New York, the largest city in the United States, to nearly $2,400 per megawatt hour (MWh) during peak evening demand. Wholesale prices in Long Island topped $7,000 per MWh.
New York ISO, the state's grid operator, warned it may initiate emergency actions after operating reserves declined.
PJM Interconnection, which covers one in five Americans as the largest U.S. power grid operator, ordered several utilities in its territory to curtail electricity to customers in voluntary reduction programs.
"Load reductions should continue until released by PJM," the grid operator said in a Tuesday afternoon directive.
PJM issued several warnings throughout the day as it battled to keep electricity flowing across overheated high-voltage transmission lines. Generation output also ebbed as gas-powered turbines operated at reduced capacity in the extreme heat.
ISO New England, whose six-state territory includes Boston, saw spot wholesale electricity prices soar past $1,500 per MWh on peak consumption around 5:30 p.m. EDT. Tuesday's prices were more than three times higher during Monday's peak demand at the start of the heat wave.
New England joined other U.S. regions deploying exigent and emergency strategies to avoid widespread outages. The U.S. Department of Energy on Tuesday ordered Duke Energy Carolina to use specific electric generating units to operate at their maximum generation output levels in the southeast.
ISO New England issued a "Power Caution" after the unexpected loss of generation left the region short of the resources needed to meet both consumer demand and required operating reserves. The grid operator said it would tap reserve resources to keep supply and demand balanced.
Duke Energy said it may not have sufficient generation available to meet unusually high demand and may have to curtail electric use to avoid outages, according to the DOE order. As a result, the utility has notified some wholesale customers to limit their use, which is expected to reduce electricity demand by up to 1,000 megawatts during peak hours.
In addition to increasing imports from adjoining regions and asking power plant operators to defer maintenance, grid operators and utilities are calling on stand-by units to boost the supply of electricity.
To prepare for Tuesday's scorching heat, ISO New England directed power plant operators not to do any testing or maintenance that would affect electric reliability.
Temperatures in Boston topped 100 F (38 C) early Tuesday afternoon, according to the National Weather Service.
ISO New England forecast that electricity demand approached 26,000 MW about 6:15 p.m. EDT on Tuesday, short of the record high of 28,130 MW set in August 2006.
(Reporting By Tim McLaughlin; Editing by Mark Porter, Bill Berkrot and Sonali Paul)