Although numerous factors contributed to the polar vortex-induced energy crisis in Texas, the central role of natural gas — or lack thereof — was becoming increasingly clear Friday as temperatures began to rise and power was restored.

Ercot generation

The unprecedented cold snap drove Texas power demand to new winter peak records rivalling peak demand figures in the summer, which is normally when the state sees the biggest surge in consumption, said International Energy Agency (IEA) analysts Keith Everhart and Gergely Molnar. 

In a report published Thursday, the authors highlighted three main factors contributing to the extended power outages that left residents without heat and water, in some cases for days: much higher electricity demand, lower natural gas production and power generation equipment outages.

They highlighted that 60% of Texans use electricity for heating, and natural gas is the leading generation source.

High temperatures in Dallas were minus 9 C last Monday (Feb. 15), Everhart and Gergely said, 25 C below the February average. Electricity prices in turn hit the cap of $9,000/MWh set by the Public Utility Commission of Texas in response to the crisis.

The cold weather also drove a 20% drop in natural gas production in the South Central region of the country.  “As a result, there wasn’t enough to supply the system’s gas generators,” the researchers noted.

The scarcity of natural gas in turn “resulted in gas generators declaring their resources unavailable (for a total of up to 31 GW),” they said.  Frozen wind turbines also led to available wind capacity being cut by 2.5 to 3 GW, “although low wind was a more significant issue.”

Coal plants, meanwhile, were operating at 40% below rated capacity as of Thursday (Feb. 18), while one of the state’s four nuclear facilities was shut down because of the weather-related loss of feed water pumps.

“Texas has a power shortage because it has a gas shortage,” Everhart and Gergely said. “Given the key role gas-fired generation plays in many power systems today, resilient power systems depend on resilient natural gas systems. For the future, system planners will need to take account of increasingly extreme weather that is both hampering the supply of power and fuel and driving up demand.”

With cold temperatures gripping much of the country, gas demand in the Lower 48 rose by more than 15% between Feb. 6 and Feb. 15, Everhart and Molnar said, which also contributed to the shortfall in Texas.

30 GW Mismatch

The Electric Reliability Council of Texas (ERCOT), which oversees most of the state’s power grid, supplying power to more than 26 million customers, ended emergency conditions on Friday as temperatures began to warm and electricity supply was restored.

The U.S. Energy Information Administration (EIA) post-mortem analysis on the Texas crisis was similar to IEA’s. 

Electricity net generation fell below ERCOT’s day-ahead forecast demand shortly after midnight on Feb. 15, a trend that continued through Feb. 18, according to a note issued Friday by EIA.

“The mismatch between demand and day-ahead forecast demand quickly grew to at least 30,000 MW on Feb. 15 before eventually narrowing to slightly less than 20,000 MW by Feb. 17,” said EIA researchers led by Mark More. The extent of the mismatch could be estimated by comparing actual demand against ERCOT’s demand forecast issued before it started implementing rotating power outages at midnight on Feb. 15.

ERCOT received only a small amount of power supply from outside the region, according to EIA, as the grid operator is a tightly controlled network with few connections outside the state.

As the leading electricity source in ERCOT, natural gas was at the center of the chaos, with prices skyrocketing amid failing infrastructure and scarcity of the molecule.

The cold snap drove a record plunge of roughly 20%, or 16 Bcf/d in U.S. dry natural gas supply during the week, according to Morgan Stanley Research. Analysts in a note said supply fell to around 75 Bcf/d, citing that the Texas and Gulf Coast regions are especially susceptible to freeze-offs since wellhead infrastructure generally is not winterized.

“This is primarily due to freeze-offs that occur when water and other liquids in the raw natural gas stream freeze at the wellhead or in gathering lines, blocking the flow of gas,” analysts said.

EIA’s researchers noted that “gas wells in the region have been affected by freezing temperatures that have disrupted production, and pipeline compressors have lost power, which have both reduced deliveries.” Gas accounts for more than 40,000 MW of ERCOT electricity supply during peak periods. 

EIA data showed “that natural gas-fired power generation fell sharply once ERCOT began implementing rotating outages at midnight on Feb. 15. Output from coal-fired plants, a nuclear facility and wind farms all fell near midnight on Feb. 15 and remained at the lower level.”

Market observers including Wood Mackenzie’s Eric Fell, senior natural gas analyst, also weighed in this week. He suggested that the inclusion of a capacity market in ERCOT, in which generators would have been paid for keeping spare capacity on standby instead of only for generation, could have mitigated the disaster.

Investigations Ahead

FERC Chairman Richard Glick said Thursday via Twitter the Commission “must get to the bottom of what happened” and “assess how these outages can be prevented the next time extreme weather occurs. And, with the climate changing, there will be a next time.”

Challenges posed to the grid such as wildfires, hurricanes and extreme cold “will only grow starker [and] more immediate,” he continued, adding, “We must do what it takes now to prepare the grid to face the threats from climate change.”

The Federal Energy Regulatory Commission and the North American Reliability Corporation announced a joint inquiry this week to investigate the power outages in ERCOT, as well as the Southwest Power Pool and Midcontinent ISO grids, Glick added.

Texas Gov. Greg Abbott said Thursday he also was asking the state legislature to investigate what happened at ERCOT during the leadup and response to the cold weather system, and “to mandate the winterization of generators and the power system” to prevent a similar catastrophe from occurring again.

House Speaker Nancy Pelosi (D-CA) also said Thursday a panel would investigate the causes of the crisis in order to prevent a repeat of the calamity.