Infrastructure and Systems
The only grid in the continental U.S. that operates as an island. How it works, why it stands alone, and what is changing.
The Island Grid
The continental United States has three major power grids. The Eastern Interconnection covers everything from the Great Plains to the Atlantic coast. The Western Interconnection covers the Rocky Mountain states to the Pacific. And then there is Texas.[1]
The Electric Reliability Council of Texas, known as ERCOT, manages the flow of electricity to about 27 million customers, representing roughly 90 percent of the state's electrical load.[2] The remaining 10 percent, including El Paso, the upper Panhandle, and parts of East Texas, connects to the Eastern or Western grids through other utilities.
This arrangement is deliberate. During the 1930s, Texas utilities realized that if they kept their transmission lines within state borders, they could avoid oversight from what would become the Federal Energy Regulatory Commission. During World War II, those utilities linked their systems together to power wartime manufacturing, forming the Texas Interconnected System. In 1970, that system was reorganized as ERCOT.[3]
The grid is not completely sealed off. ERCOT has two direct-current ties to the Eastern Interconnection and three ties to Mexico. These connections can move limited amounts of power during emergencies, but they cannot transfer enough to offset a major shortfall.[4] During Winter Storm Uri in February 2021, those ties proved far too small to prevent catastrophe.
How ERCOT Fits
Grid operator, not utility
ERCOT balances supply and demand in real time and oversees the wholesale market. It does not own power plants, transmission lines, or sell electricity to consumers.
State-regulated, not federal
The Public Utility Commission of Texas oversees ERCOT. Because the grid does not cross state lines, most federal electricity regulation does not apply.
Deregulated retail market
Most Texas consumers choose their electricity provider from competing retail companies. Prices fluctuate with wholesale market conditions, which can create both savings and risk.
Limited outside help
The DC ties to other grids and Mexico can move some power in emergencies, but far less than what is needed during a grid-wide crisis. Texas must generate nearly all of its own electricity.
Generation
Natural gas remains the backbone of ERCOT, accounting for roughly 44 percent of electricity generation from 2021 through 2025.[5] Gas-fired plants provide the dispatchable generation that keeps the grid balanced when demand spikes or when wind and solar output drops.
The shift in the generation mix has been dramatic. Solar's share grew from 4 percent to 12 percent between 2021 and 2025, and the U.S. Energy Information Administration projects that solar generation in ERCOT will surpass coal for the first time in 2026.[5] Wind and solar together met 36 percent of ERCOT demand in the first nine months of 2025.[6]
Battery storage has grown even faster. Texas entered 2026 with 13.9 gigawatts of grid-scale battery capacity, nearly double the 7.8 gigawatts at the start of 2025.[7] Batteries help balance the grid during tight conditions, absorbing excess solar during the day and discharging during evening peak hours. Most current systems are limited to one to two hours of duration, which helps with daily peaks but cannot sustain power through a multi-day event.
Natural gas
~44%
of generation, 2021-2025 average. Still dominant, but its share is gradually declining as renewables grow.
Wind + Solar
36%
of demand met by wind and solar in Jan-Sep 2025. Solar alone grew from 4% to 12% since 2021.
Battery storage
13.9 GW
operational entering 2026. Doubled in a single year. Most systems limited to 1-2 hours of discharge.
Coal
13%
down from 19% in 2021. Expected to fall below solar output for the first time in 2026.
Demand
ERCOT had the fastest electricity demand growth among U.S. grids between 2024 and 2025. Demand in the first nine months of 2025 rose 5 percent over the same period in 2024, and 23 percent above the same months in 2021.[6]
The drivers are industrial. Data centers, semiconductor manufacturing plants, large-scale electrification in the Permian Basin oil fields, and continued population growth are all pulling more power from the grid.[8] As of late 2025, ERCOT was assessing more than 233 gigawatts of large-load interconnection requests. More than 70 percent of those requests came from data centers.[9] For context, ERCOT's all-time peak demand record is 85,508 megawatts, set in the summer of 2023.[8]
A winter peak demand record of 80,525 megawatts was set in February 2025, a demand level typically seen only in summer, driven by electric heating loads during cold weather.[8] The gap between summer peaks and winter peaks is narrowing, which means the grid faces stress in both directions.
27M
Customers served by ERCOT, roughly 90% of Texas
ERCOT
85.5 GW
All-time peak demand record, set summer 2023
ERCOT CEO testimony, March 2025
233 GW
Large-load interconnection requests in the queue, 70%+ from data centers
ERCOT Board, Dec 2025
+23%
Demand growth in ERCOT from Jan-Sep 2021 to the same period in 2025
EIA, Oct 2025
After Uri
Winter Storm Uri in February 2021 pushed the ERCOT grid to the edge of total collapse. Generators froze, gas supply lines failed, and controlled rolling blackouts left millions without power for days in subfreezing temperatures. Nearly 250 people died.[10] An uncontrolled, full grid collapse would have been far worse, potentially requiring weeks of black-start procedures to restore power.
The legislative response came quickly. Senate Bill 3, signed in 2021, required weatherization of power plants and natural gas facilities and strengthened coordination between the gas and electric systems. The Legislature expanded the Public Utility Commission of Texas from three to five commissioners. All three commissioners who served during Uri were replaced.[11]
In November 2023, Texas voters approved the Texas Energy Fund, a constitutional amendment authorizing up to $10 billion for grid investment. The bulk of the funding, $7.2 billion, supports low-interest loans and completion bonus grants for new dispatchable generation facilities within ERCOT. Another $1.8 billion funds microgrids and backup power for critical facilities. One billion dollars goes to grid modernization and weatherization for the portions of Texas outside ERCOT.[12]
What Changed
Weatherization standards (SB 3, 2021)
Power plants and gas facilities must now meet weatherization requirements. ERCOT has conducted over 3,362 inspections since 2021 to enforce compliance.[8]
Texas Energy Fund ($10B, 2023)
Voter-approved constitutional amendment funding new dispatchable generation, microgrids, backup power, and grid modernization. First loan agreement signed June 2025. First project completed April 2026.[12]
Expanded oversight (SB 2154, 2021)
PUCT expanded from three to five commissioners. Complete leadership turnover since Uri.[11]
Firm Fuel Supply Service
New program providing backup fuel options to generators during extreme cold, addressing one of Uri's root causes: gas supply failures to power plants.[8]
Transmission investment
Planned transmission spending expected to reach $7.5 billion in 2026, nearly double the $3.97 billion spent in 2025, to connect new generation and serve growing demand.[13]
What to Watch
Isolation in a crisis
The DC ties to other grids remain small. If generation falls short across ERCOT during a major weather event, there is no large neighboring grid to import from. This is a structural feature of the Texas system, not a bug that can be patched with policy.
Demand outpacing supply
The queue of large-load interconnection requests dwarfs current capacity. Not all will be built, but even a fraction could strain the grid. ERCOT anticipates 8.8 gigawatts of new gas generation by 2029, but supply chain constraints and equipment costs may limit additions.[14]
Intermittency at scale
With wind and solar providing over a third of generation, the grid depends more on weather conditions. Battery storage helps smooth daily cycles but cannot yet sustain power through multi-day events like a prolonged winter storm or extended cloud cover.
What This Means for Your Household
If you live in ERCOT territory, your household depends almost entirely on in-state generation. The reforms since Uri are meaningful, but isolation remains a structural reality. That shapes decisions about backup power, generator sizing, and how many days of self-sufficiency to plan for. The energy preparedness guide covers all of it.
Energy preparedness guideFailure Events in Texas
Winter Storm Uri, 2021
The grid failure that killed nearly 250 people and brought Texas within minutes of total collapse. The defining event in modern ERCOT history.
Disaster History: Winter Storm Uri
The full disaster history, covering the storm's meteorology, the cascading failures, the human cost, and the long recovery.
This is the Texas profile in the Power Grid series.
How the U.S. Power Grid Works (national overview) ↑Sources