Texas’s largest and oldest electric power cooperative on Monday filed for bankruptcy protection in federal court in Houston, citing a disputed $1.8 billion bill from the state’s grid operator. Brazos Electric Power Cooperative Inc is one of dozens of electricity providers facing enormous charges stemming from a severe cold snap last month. The fallout threatens utilities and power marketers who collectively face billions of dollars in blackout-related charges, executives said. Unusually frigid temperatures knocked out nearly half of the state’s power plants in mid-February, leaving 4.3 million people 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 at high rates […]