There’s a New Kind of Energy Risk: Cold Winter Mornings

The Texas grid has had two close calls already this week, leading ERCOT, the electricity market that covers about 90% of the state, to ask households, businesses, and government agencies to conserve energy due to high demand. These calls for moderation are nothing new — ERCOT issued several of them issued this summer, when temperatures were over 100 degrees Fahrenheit in much of the state. What’s new is that these calls weren’t coming on sweltering afternoons, but rather on freezing mornings.

Traditionally, we start to get nervous about the electric grid in the summertime around sunset. With air conditioners running and people getting home from work, demand for electricity goes up just as a major source of it (that is, solar power) starts to taper off. This effect is known in California as the “duck curve,” and in Texas as the “dead armadillo curve,” referring to the shape of graphs showing hourly demand on the grid.

The basic issue on very cold days like the ones Texas has been experiencing is that people wake up and start consuming electricity — especially heat, which is largely electric in Texas — before the sun comes up. Solar power provides around a fifth of the state’s electricity in the afternoon, even in winter. But at 7 a.m. on a January morning in Austin, the sun is nowhere to be found. Add on the fact that the rest of the system, especially its natural gas production system and power plants, is at risk of weather-related issues — sometimes literally freezing — and winter, especially winter mornings, become very touch-and-go.

While the Texas grid is unique in its relatively free-market organization and isolation from the rest of the country, it is certainly not unique in experiencing winter — if anything, more of the country may start to look like Texas. Not every decarbonized energy system would be at the mercy of very cold mornings, and batteries for storing excess electricity on the grid can help fill gaps when solar is unavailable. But decarbonization nationwide will necessarily lead to load growth, which means that making it so you can get out of bed and keep your toes warm will put pressure on electricity systems everywhere.

New England’s grid is forecasting that its winter peak demand will increase around 3% per year, three times faster than the summer peak, with some 3,000 megawatts of that 6,000 to 9,000 MW projected increase coming from electrification of home heating. In New York, grid planners expect heating-related demand to double over 30 years, and even surpass summer demand by around 2040 thanks to a combination of electric vehicle adoption and the use of heat pumps for home heating. In Quebec, which features a unique combination of extremely cold winter temperatures and plentiful green energy in the form of hydropower from its massive dams, plus home heating systems that are mostly electric already, demand tends to peak on very cold winter days.

While Texas is unlikely to pursue climate policy as aggressive as New England, New York, or (shudders) Canada, it does have a burgeoning renewables sector and an incumbent electrified home heating system that leaves it vulnerable to weather-dictated swings in demand.

And Texas has been uncommonly cold lately. In Austin, temperatures have remained below freezing since very early Sunday morning, dipping as low as 18 degrees on Monday and Tuesday mornings. In Houston, temperatures got as low as 20 on Tuesday morning. The system burst through its January demand record by 5,000 megawatts early this week, breaking a record set in late 2022 during Winter Storm Elliott.

This time, the grid was able to meet the high winter demand without malfunctioning, unlike during 2021’s Winter Storm Uri, when much of the state’s generation system tripped offline for days, resulting in prolonged blackouts and hundreds of deaths.

Since Winter Storm Uri, advocates and analysts have bemoaned that while Texas does have electrified heating, it tends to be inefficient resistance heat (think electric furnaces and baseboard heating) instead of more efficient heat pumps, which is then called upon to heat homes built with little or sometimes no insulation. At very low temperatures, according to one expert report on Winter Storm Uri, “uninsulated homes cannot be heated effectively.” Texas only adopted a mandatory building code in 2001; last year, the state’s Governor Greg Abbott vetoed a bill that would have updated codes for new buildings in the course of a fight with the state legislature over property taxes.