(Adds Biden emergency declaration)
Feb 15 (Reuters) - The state of Texas continued to reel under a deep freeze, leaving utilities scrambling to meet record power demand and forcing the state's grid operator to enforce rotating blackouts early on Monday.
President Joe Biden approved the state's emergency declaration, unlocking federal assistance to tackle the rare deep freeze.
Apart from Texas, much of the United States from the Pacific Northwest through the Great Plains and into the mid-Atlantic states has been in the grip of bone-chilling weather over the weekend, featuring snow, sleet and freezing rain.
The Electric Reliability Council of Texas (ERCOT) has sought to cut power use in response to winter record of 69,150 MW on Sunday evening, more than 3,200 MW higher than the previous winter peak in January 2018.
Reserves have dropped below 1,000 MW and transmission companies have been ordered to reduce demand on system, ERCOT said.
"Traffic lights and other infrastructure may be temporarily without power," the agency said on Twitter https://twitter.com/ERCOT_ISO/status/1361215084010352644.
A level three emergency notice was issued by the regulator, urging customers to limit power usage and prevent an uncontrolled system-wide outage.
The National Weather Service said that an Arctic air mass had spread southwards, well beyond areas accustomed to freezing weather, with winter storm warnings posted for most of the Gulf Coast region, Oklahoma and Missouri.
The storms knocked out nearly half the wind power generation capacity of Texas on Sunday.
Of the 25,000-plus megawatts of wind power capacity normally available in Texas, 12,000 megawatts was out of service on Sunday morning, an ERCOT spokeswoman said.
Wind generation ranks as the second-largest source of electricity in Texas, accounting for 23% of state power supplies last year behind natural gas, which served 45%, ERCOT estimates.
Energy traders last week said that some 5-minute power prices in Texas approached $4,000 per megawatt hour. That compares with an Ercot North average of $26 in 2020. (Reporting by Aishwarya Nair and Diptendu Lahiri in Bengaluru Editing by Bernadette Baum and David Goodman)
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