Brazos Electric Power Co.

Operative filed for Chapter 11 after racking up an estimated $2.1 billion in charges which the states Grid Operator, known as Market said went unpaid.

Brazos, which supplies electricity to more than 660,000 consumers across the state, is one of dozens of providers facing enormous charges stemming from the deep winter freeze.

The company said the fallout threatens utilities and power marketers, which collectively face billions of dollars in blackout related charges.

Unusually high frigid temperatures knocked out nearly half of the state's power plants in mid February, leaving 4.3 million Texans without heat or light for days and bursting water pipes that damaged homes and businesses.

Brazos and others that committed to provide power to the grid and could not were required to buy replacement power as prices soared.

ERCOT triggered the squeeze when it pushed up spot market rates to $9000 per megawatt hour over more than four days and levied huge fees for services.

Pre storm prices were less than $50 per megawatt hour, according to market data.