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According to the state climatologist, summer 2023 was the second hottest on record. With most days hitting 105°F or more, ERCOT set 10 new peak demand records and an all-time high peak demand record on August 10 of 85,464 MW.
Yet, in spite of lawmaker’s finger pointing in the statehouse over intermittency and reliability, Texans relied on green energy to keep their electricity flowing all summer long, all while Texas electricity rates remained some of the lowest in the US, according to PowerChoiceTexas.org. On multiple days, solar and wind kept the lights on when “dispatchable” thermal plants in Texas tripped offline from the heat.
Extreme heat, extreme demand
Even absent the extreme heat this summer, the sheer volume of electricity customers drove energy demand. According to TexasElectricityRatings.com, an average Texas home uses well over 1,000 kWh in the summer. That’s not worrisome until you consider how fast the state’s population grew over the past 20 years. US Census data shows that the state’s population surpassed 30 million in 2022. Between 2000 to 2022, the state gained 9,085,073 residents — a 43.4% jump.
That 43% increase correlates with increases in summer peak demand. ERCOT data shows that peak demand in August 2000 grew from 57,606 MW by nearly 40% to 80,148 MW in July 2022. Add in this summer’s 85,464 MW, an increase of 48%.
No wonder ERCOT scrambles each year to meet summer demand.
Green energy’s share of the load
Luckily, Texas was in the midst of a utility-scale renewables building boom this year. One reason comes from federal and state tax incentives that can cover building costs by a third or more. The EIA reported that between September 2022 and May 2023, ERCOT added more than 4,000 MW of wind and solar. This brought the total installed green capacity to nearly 40,000 MW.
In May, ERCOT’s Summer Seasonal Assessment of Resource Adequacy (SARA) predicted a peak summer demand of 82,739 megawatts, 4% higher than in 2022. All told, ERCOT planned to have over 97,000 MW of total capacity available. But the problem with available capacity is that no matter if it’s green or thermal, it’s not always available.
Reliable green energy sources
It’s a dead certainty under the Texas sun that stuff overheats, breaks, or burns out. Generators and transmission lines are no different.
Transmission lines get hot from the sun and the electricity they carry. The hotter they get, the more they resist moving current — which makes them hotter. If they sag into tree tops, they can short out and shut down whole sections of the grid. Though limiting a powerline’s transmission load cuts the risk for failure, it can cause supply problems where the power is needed.
Since natural gas, coal, biomass, and nuclear all use heat to make power, extremely hot weather can trip them offline more easily. So, the SARA’s estimated 65,091 MW of thermal capacity included the need to cover 5,034 MW or more of it going offline.
For green energy, its reliance on sun and wind makes their output capacity intermittent and variable. However, their output usually stays within a predictable seasonal range. And it’s this property that keeps green energy reliable.
In summer, wind speeds usually fall during the day and rebound at night. Although Texas has over 37,000 MW of wind power, ERCOT ‘s SARA planned for about one fourth of its installed capacity, around 10,000 MW. And summer sun meant ERCOT could plan for output of 12,264 MW of 15,659 MW of solar installed capacity, about 80%.
Texas’ biggest summer demand period falls at about 5 p.m. That’s because wind and solar easily cover midday, but solar output dwindles as the sun sets. Plus, after the Summer Solstice (usually June 20 or 21), solar output wanes earlier and earlier. In early July, sunset is at about 8:30 p.m. By September 15, it’s at 7:26 p.m. And if evening wind and battery storage couldn’t rebuild output fast enough, it can leave a hole that grid-planners need thermal plants to fill. Or so it seemed.
Just in time supply
The first record peak of 80,828 MW that hit on June 27 was handled mostly by natural gas plants. But, on June 28, wind and solar generated 31,468 MW, covering 9,600 MW of thermal plants that couldn’t take the heat. The EIA reports for the next two days, renewables covered 55% of total generation all day and handled 43% to 47% in the evening peak load hours of 4:00 to 8:00 p.m.
And for the rest of the summer, renewables kept shouldering sizable chunks of the ERCOT load. One key observation from the Institute for Energy Economics and Financial Analysis shows for 91 of 93 days from June 15 to September 15, solar consistently covered 10% to 16% of peak demand from 5 to 6 p.m. And this includes the white knuckle period from August 29 to 30 when 11,200 MW of thermal generation failed.
Texas’s future relies on green energy
This summer, ERCOT issued 12 voluntary conservation notices. The only Energy Emergency Alert came on September 6 when ERCOT curtailed an overloading transmission line carrying energy from wind farms in south Texas to Dallas. In short, the summer’s only grid emergency came from too much available green energy and not enough capacity to deliver it.
To be sure, green energy saved Texas this summer. And that happened because Texas relied upon its decades-long investment in green energy. However, future grid reliability remains mired in short-term goals. Consider that ERCOT’s long term planning projects the summer peak demand to be 90,978 MW in 2032; an increase of 6.45184%. That’s worrisome because even with a conservative estimate of data from the Texas Demographic Center, the population is projected to hit 34,894,429 by 2030, an increase of 16.3148%.
It’s a near certainty the state’s population will keep booming under an increasingly brutal summer sun. The Texas grid will need to be free to invest in cheaper and more reliable energy capacity for all Texans. And that means green energy.
