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.

Oddly enough, Texas electricity rates remained some of the lowest in the US, according to PowerChoiceTexas.org. The reason is that solar and wind kept the power flowing when reliable, “dispatchable” thermal generators couldn’t stand the heat. In spite of what lawmakers in Austin thought, they and other Texans relied on green energy to keep their AC units humming all summer long.

Data Source:
•  TX Population by year from: https://www.macrotrends.net/states/texas/population

• Peak Demand data from ERCOT:  https://www.ercot.com/static-assets/data/news/Content/a-peak-demand/records-yearly-archive.htm

Extreme Heat, Extreme Demand, Extreme Load

Texas summers are always hot. But the sheer volume of electricity customers drove energy demand this summer. According to TexasElectricityRatings.com, an average Texas home uses well over 1,000 kWh in the summer. That’s a lot of houses when you consider the state’s population growth in the past 20 years. US Census data shows that the population surpassed 30 million in 2022. So, 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 and it’s an increase of 48%. 

No wonder ERCOT scrambles each year to meet summer demand.

Green Energy’s Share of the Load

Over the past year, federal and state tax incentives helped launch the utility-scale renewables boom in Texas. 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. ERCOT planned to have over 97,000 MW of total generator capacity available. But the problem with generators is that no matter if it’s green or thermal, they’re not always available when you need them.

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 this risk, it limits supply and raises prices.

Thermal generators, like natural gas, coal, biomass, and nuclear, use heat to make power. ERCOT planned to have 65,091 MW of thermal capacity available. But, thermal plants are more prone to go offline during extremely hot weather. So, ERCOT planned to cover 5,034 MW or more of it going offline. 

Green energy’s reliance on sun and wind makes their capacity intermittent and variable. But, their output usually stays within a predictable seasonal range, making green energy very 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 planned for about 1/4 of its installed capacity; around 10,000 MW. For solar, ERCOT planned for an output of 12,264 MW of 15,659 MW of installed capacity; about 80%.

While wind and solar easily cover midday, solar output dwindles as the sun sets. That’s a problem because the biggest summer demand period starts at about 5 p.m. 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. So, if evening wind and battery storage can’t take over fast enough, it can leave a hole that grid-planners need to fill with more expensive thermal plants. Or so it seemed.

Just In Time Supply

Natural gas plants tackled the first record peak of 80,828 MW that hit on June 27. But, when 9,600 MW of thermal plants failed in the heat on June 28, wind and solar jumped in with 31,468 MW. The EIA reports that for the next two days, renewables covered 55% of total generation all day and handled 43%–47% in the evening peak load hours of 4:00–8:00 p.m.

For the rest of the summer, renewables kept shouldering sizable chunks of the ERCOT load. The Institute for Energy Economics and Financial Analysis found that for 91 of 93 days from June 15 to September 15, solar consistently covered 10% to 16% of peak demand from 5 – 6 p.m. And this includes the white knuckle period from August 29 – 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 when a transmission line carrying energy from wind farms in south Texas to Dallas threatened to overload. In short, ERCOT’s only summer’s grid emergency was due to too much 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 debate. Consider that ERCOT’s long term planning projects the summer peak demand to be 90,978 MW in 2032; an increase of 6.45184%. But 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.