A rare deep freeze in Texas that raised demand for power forced the U.S. state’s electric grid operator on Monday to impose rotating blackouts that left more than 2 million customers without electricity.

The PowerOutage.us website – an ongoing project to track power outages – said 2,703,967 Texas customers were experiencing outages at 10:49 p.m. CST (1649 GMT).

President Joe Biden declared an emergency on Monday, unlocking federal assistance to Texas, where temperatures on Monday ranged from 21 to minus 8 degrees Fahrenheit (minus 6 to minus 22 Celsius).

Houston’s George Bush Intercontinental Airport said in a statement that its airfield would remain closed until 1 p.m. CST (1900 GMT) while the city’s Hobby Airport will cease operations until at least Tuesday due to the inclement weather.

Apart from Texas, much of the United States from the Pacific Northwest through the Great Plains and into the mid-Atlantic states was in the grip of bone-chilling weather over the three-day Presidents Day holiday weekend.

In Louisiana, where freezing temperatures also prompted power outages and road closures, some parishes were implementing curfews to keep residents off the road.

RECORD DEMAND

The Electric Reliability Council of Texas (ERCOT) sought to cut power use in response to a winter record of 69,150 MW on Sunday evening, more than 3,200 MW higher than the previous winter peak in January 2018.

About 10,500 MW of customer load was shed at the highest point, enough power to serve approximately two million homes, it said, adding that extreme weather caused many generating units across fuel types to trip offline and become unavailable.

As of early Monday, it said over 30,000 MW of generation had been forced off the system, and rotating outages would likely last throughout the morning and could be initiated until the weather emergency ended.

“Controlled outages will continue through today and into early tomorrow, possibly all of tomorrow,” Dan Woodfin, director of systems operations at ERCOT, said in a briefing on Monday.

The storms knocked out nearly half the Texas wind power generation capacity on Sunday. Wind generation ranks as the second-largest source of electricity in Texas, accounting for 23% of state power supplies, ERCOT estimates.

Of the 25,000-plus megawatts of wind power capacity normally available in Texas, 12,000 megawatts were out of service on Sunday morning, an ERCOT spokeswoman said.

An emergency notice issued by the regulator urged customers to limit power usage and prevent an uncontrolled systemwide outage.

The National Weather Service said 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 spot price of electricity on the Texas power grid spiked more than 10,000% on Monday. [NGA/]

The cold snap has led to production disruptions and shutdowns in oil refineries and natural gas facilities across Texas.[REF/OUT]

Power grid operator Southwest Power Pool, which coordinates electricity supply across a vast swath of the country, on Monday declared an “Energy Emergency Alert Level 2” due to energy shortages.