It’s getting hot in Texas. Forecast highs for Tuesday are 89 degrees Fahrenheit in Houston, 92 in San Antonio, and 90 in Dallas. ERCOT, which operates the energy market that covers around 90% of the state, issued an “extreme hot weather event” warning and a “weather watch” due to “unseasonably high temperatures” — and “high levels of expected maintenance outages.”
The whole country, but particularly Texas, is playing chicken with its existing fleet of natural gas-powered electricity infrastructure. While the weather-dependence of solar and wind are both obvious and well-known, gas, too, can be susceptible to nature’s fluctuations. High temperatures mean high demand, while very low temperatures can literally freeze whole gas production, distribution, and generation system, with catastrophic consequences.
Natural gas powers around 60% of Texas’ electricity. While Tuesday’s is far from the hottest weather the state will face this year, it comes at what can be a fragile time for the grid. This is the end of the spring maintenance season, when power plant operators have a window to schedule outages necessary to perform maintenance after winter and ahead of summer, when electricity demand spikes again — what ERCOT calls the “shoulder seasons.”
But weather increasingly does not conform to the plans of market regulators, with temperatures rising earlier in the year and falling later, impinging on that shoulder space. In April, ERCOT had to ask power plants to delay outages they had already planned due to high temperatures in parts of the state.
Shutting down a natural gas power plant can be fraught in Texas, where authorities are wary of destabilizing the grid. Other than 2021’s Winter Storm Uri, which caused days of blackouts and hundreds of deaths, one of the state’s worst-ever blackouts happened in April 2006, when high temperatures coincided with — you guessed it — planned outages for maintenance. Texas is not the only place that gets hot in the summer, of course, but its grid is both isolated from the rest of the country and is dealing with substantial growth in power demand, which means it’s more likely to bump up against its limits.
“We’ve had a couple of pretty hot days and have more hot weather this week,” University of Texas professor Hugh Daigle told me. “What’s happening is that we’ve been operating close to the limit of available supply at peak demand.”
While the grid in Texas has remained stable so far this spring — albeit with some wild price spikes at times — delaying planned outages risks future unplanned power failures if operators fall behind on maintenance. Those failures are most likely to occur during the summer months, when high demand from air conditioning adds to stresses caused by the heat and ERCOT is less likely to allow the plants to come offline. In the best case scenario, a strained grid “only” results in electricity prices spiking. In the worst, it leads to blackouts and deaths from extreme heat.
Along with three of his University of Texas colleagues, Joshua Rhodes, Aidan Pyrcz, and Michael Webber, Daigle recently published a paper showing that as Texas warms, the times when it’s “safe” to have a large number of planned outages may shrink.
Average temperatures in the state rose 0.8 degrees Celsius from 1895 to 2021, and are projected to go up another whole degree by 2036. While that may sound like a small change, this would increase the number of 100 degree Fahrenheit days — which often mean record-breaking electricity usage — by some 40%.
While it may seem like a warming trend could have a symmetric and offsetting effect on the grid — hotter summer days that lead to record air conditioning demand but also warmer winter days that create less strain on electric heat — the researchers found that instead, the shoulder seasons were getting impinged on both sides. Compared to the 1950s, mild spring weather has been starting and ending earlier. At mid-century, spring started near the beginning of March; now it’s closer to the beginning of February. The start of fall, meanwhile, slid from the beginning of November later toward the middle of the month.
If maintenance in the spring shoulder season can just occur just from March to May, “maintenance periods will no longer coincide with periods of low expected demand,” Daigle told me. And if it’s just in the fall season, which could shrink to October and November, “it may be unreasonable to expect power plants to be able to forgo spring maintenance.”
“If you look at climate models and how average temperatures change,” Daigle said, “those two periods” — before the cold of winter and the heat of summer — “could merge into a single period in December and January.”
Just one shoulder season introduces extreme risks, Daigle explained. “We still do get winter storms. It’s December and January and you have a lot of stuff down for planned maintenance, and something like Uri comes through — we’re up a creek.”
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