During the week before Feb 15th, ERCOT attempted to regain some of these generators by issuing an Operating Condition Notice (OCN) calling for their return. ERCOT also relaxed emissions restrictions to keep older, more polluting plants from being sidelined by emissions caps during this emergency event.
Some of these units on outage were likely unable to secure gas on such short notice as the weekend’s gas prices rapidly increased from $7 per mmBTU on Thursday to $150 per mmBTU by the weekend due to supply concerns around freeze-offs and heating demand. Unlike in the summer months, during extreme winter peaks gas is diverted for residential heating, decreasing availability for power plants. Additionally, unlike colder markets, ERCOT’s gas fleet has a low percentage of dual-fuel generators that can switch to distillate or fuel oil.
Whether due to gas shortage or unresolvable maintenance issues, despite ERCOT’s best efforts thermal generation on outage totals remained at 14 GW into Monday morning. Plants are not penalized for ignoring ERCOT’s OCN. Instead of returning units into winter’s strongest demand peak, over the span of four hours Monday morning, outage totals more than doubled to 32 GW, far surpassing ERCOT’s highest thermal outage level recorded in the last nine years. Freezing rain and cold temperatures decimated coal, natural gas, and nuclear power plants alike, with emergency equipment failures, broken sensors, frozen coal piles and more issues slashing ERCOT’s thermal generation capacity from 70 to 45 GW in the span of a few hours.
The freezing temperatures also took their toll on gas production. We estimate that on Tuesday, about 18.7 billion cubic feet per day of gas production was lost because of freeze-offs. That is equivalent to about a fifth of total US output.