Green Energy Powered Texas When Gas Power Plants Failed

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 lawmakers protesting its intermittency and unreliability, Texans relied on green energy to keep their electricity flowing all summer long. On multiple days, solar and wind kept the lights on when "dispatchable" thermal plants tripped offline because of the heat. And yet, Texas electricity rates remained some of the lowest in the US, according to PowerChoiceTexas.org.  

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 Demand From Extreme Heat

Hot Texas summer temps aside, 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, and that’s an increase of 48%. 

No wonder ERCOT scrambles each year to meet summer demand.

Green Energy's Share of the Load

Federal and state tax incentives helped spur this past year's utility-scale renewables building 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. To cover it, ERCOT planned to have over 97,000 MW of total available generator capacity. But the reality of generator capacity is that no matter if they’re green or thermal, generators are not always available.

Reliable Green Energy

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 grid sections. Limiting a powerline's transmission load cuts this risk, but it can reduce supply and raise customer prices.

Thermal generators, like natural gas, coal, biomass, and nuclear, use heat to make power. ERCOT’s SARA estimated it had 65,091 MW of thermal generation capacity. But extremely hot weather can trip these plants offline more easily. For that reason, ERCOT needed to cover 5,034 MW or more of it going offline. 

Green energy’s reliance on sun and wind makes their output capacity intermittent and variable. But, their output usually stays within a predictable seasonal range. 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 1/4 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%.

In the summer, wind and solar easily cover midday, but solar output dwindles as the sun sets. That’s a problem since the big demand period starts about 5 p.m. 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. If evening wind and battery storage don’t come up fast enough, it can leave a hole for grid-planners to fill in with thermal plants. Or so it seemed.

Just In Time Supply

Natural gas plants mostly handled the first record peak of 80,828 MW that hit on June 27. But, on June 28, 9,600 MW of thermal plants couldn't take the heat. Wind and solar covered it, generating 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 summer, renewables kept shouldering sizable chunks of the ERCOT load. The Institute for Energy Economics and Financial Analysis observed that for 91 of 93 days from June 15 to September 15, solar consistently met 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

ERCOT issued 12 voluntary conservation notices during this past summer. The only Energy Emergency Alert came on September 6 when a transmission line carrying energy from wind farms in south Texas to Dallas overloaded. In short, the only grid emergency came from too much available green energy and not enough capacity to deliver it.

To be sure, its decades-long investment in green energy is what saved Texas this summer. However, future grid reliability remains debatable. ERCOT's long term planning projects summer peak demand in 2032 to be 90,978 MW; an increase of 6.45184%. Yet, a conservative estimate of data from the Texas Demographic Center, projects the population to hit 34,894,429 by 2030; an increase of 16.3148%

Certainly, 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.

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