Is there enough electricity to keep air conditioners running in the Texas summer heat?
The Electric Reliability Council of Texas, which operates Texas’s power grid, asked Texans to conserve energy on Monday afternoon due to record high demand driven by triple-digit temperatures.
ERCOT asked people in the state to turn up their thermostats a degree or two and postpone running major appliances or pool pumps between 2 to 8 p.m. Monday. ERCOT has issued conservation appeals more than four dozen times since 2008 to manage grid operations. This notification is issued when projected reserves may fall below 2,300 MW for 30 minutes or more.
The “projected reserve capacity shortage” is because of extreme hot weather, ERCOT said. Hot temperatures were forecast for Monday, with highs hitting 102 degrees, according to the National Weather Service in Fort Worth. An Excessive Heat Warning and Heat Advisory is in effect for most of the region through 9 p.m. Tuesday.
The heat is not going away anytime soon — with 100-degree days in the forecast for Fort Worth well into next week, according to the weather service. This means demand for power to run air conditioners can only spike.
Forecast demand is 79,671 MW, ERCOT said, more than the peak summer demand of 77,317 MW that ERCOT forecast in its Seasonal Assessment of Resource Adequacy.
“At this time, we do not anticipate (rolling blackouts) happening. We are not in an emergency situation at this time,” an ERCOT spokesperson told the Star-Telegram.
“Our control room officially issued a watch, but we are not in an emergency/Energy Emergency Alert status,” the statement said. “We have asked for a voluntary reduction of use at this time. ERCOT is encouraging Texans to voluntarily reduce electric use this (Monday) afternoon from 2 p.m. - 8 p.m., when safely able to do so. Tips can be found on the Public Utility Commission’s Power to Save Texas website.”
How does the Texas power grid work?
President Franklin D. Roosevelt passed the Federal Power Act in 1935, regulating electric companies operating across state borders. To avoid federal regulation (namely the Federal Energy Regulatory Commission), Texas decided to operate independently from other states.
During World War II, the 10 independent power grids in Texas merged, creating the Texas Interconnected System. ERCOT was formed in 1970, and the state’s electricity market was deregulated in 1999.
Thus, Texas is the only state with its own power grid, while the rest of the U.S. runs on two power grids, either the Western Interconnection or the Eastern Interconnection. That’s possible thanks to Texas having the highest energy production in the country — and two time zones to serve, meaning two peak times of demand each day.
The Electric Reliability Council (ERCOT) serves as the grid operator for 90% of the Texas population. The grid operator connects more than 46,500 miles of transmission lines and more than 650 power generation facilities, providing electricity to more than 26 million customers. ERCOT schedules and dispatches electricity on a daily basis, coordinating power plants and electric utility companies (TDUs) in the state, according to Quick Electricity. While not subject to federal regulation, ERCOT is subject to the Public Utility Commission of Texas (PUCT) and the Texas Legislature. Power plants are concentrated in Houston, San Antonio and Dallas-Fort Worth, and the Public Utility Commission of Texas has to give approval before a new power plant is connected to the grid.
The Texas power grid is composed of three parts, per Quick Electricity:
Power generators sell electricity in a wholesale market, wherein prices are determined by supply and demand.
Retail electricity providers buy energy in bulk and resell it to homes and businesses, offering various electricity plans including fixed-rate, variable-rate, indexed-rate and prepaid.
Transmission and distribution utilities manage the grid, controlling power lines and transformers. There are six transmission and distribution utilities: AEP Texas Central, AEP Texas North, CenterPoint Energy, Oncor, Texas-New Mexico Power, and Sharyland Utilities. Each territory in Texas is assigned a TDU, which means you cannot choose your utility company.
Neighboring grids Western Electricity Coordinating Council, Southwest Power Pool and Southeastern Electric Reliability Council, which cover small areas of Texas, are subject to the FERC because they operate across multiple states, according to Quick Electricity.
Deregulation has helped Texas keep its electricity rates below the nation’s average, per Quick Electricity, but the power grid cannot draw power from neighboring states during an emergency. In 2011, following rolling blackouts statewide, Texas imported some power from Mexico.
Because of its isolation, the Texas grid depends on internal resources to provide electricity, making it vulnerable to events like the February 2021 winter storm. Because of the extreme cold weather, natural gas production was cut and wind farms went offline. Since natural gas and wind are the main power sources in Texas, providing 52.3% and 19.6% of the state’s electricity, there were rolling blackouts across the state.
This time around, ERCOT is again dealing with low wind resources. Wind generation is currently generating significantly less than what it historically generated in this time period, ERCOT said. Current projections show wind generation coming in at 8% of its capacity.
What are rolling blackouts and why do they happen?
As demand increases, grid operators have to keep up. Failing to meet that high demand, or an outage happening at plants or power lines, means risking a blackout, according to Choose Texas Power.
These are some of the most common causes of blackouts, according to Quick Electricity:
Having malfunctions at one or more power plants, reducing the electricity supply below the consumption level. As more megawatts of power plant capacity are taken offline, the risk of blackouts increases.
Having a higher consumption than expected in homes and businesses, exceeding the available generation capacity. This is often the result of poor planning, and a blackout can occur even when all power plants are working properly.
Having an electrical fault that affects the grid, which disconnects power plants from consumers. Electricity cannot be delivered to the point of use in this case, even when there is enough generation capacity.
Rolling blackouts are used as an emergency measure when the ERCOT grid is incapable of keeping up with demand. ERCOT uses rolling blackouts to reduce demand when the grid’s operating margin falls below the safety limit of 1,000 MW. ERCOT uses an Energy Emergency Alert system to inform the public about the current condition of the grid and decide if blackouts are necessary.
If projected reserves do fall below 2,300 MW for 30 minutes or more, ERCOT will declare a Level 1 Energy Emergency Alert and may import up to 1,220 MW from neighboring electric grids. At Level 2, when the operating margin decreases below 1,750 MW and is not expected to recover within 30 minutes, ERCOT will start disconnecting large consumers who have an agreement to be switched off during emergencies.
If operating reserves drop below 1,000 MW and are not expected to recover within 30 minutes, ERCOT moves into a Level 3 EEA. ERCOT may then instruct transmission companies to reduce demand on the electric system through controlled outages. These electricity service interruptions are called rolling blackouts because different parts of the grid are switched off by turns and temporarily, normally from 10 to 45 minutes, according to Quick Electricity. They prevent an uncontrolled system-wide outage and are used to bring operating reserves back to a safe level and protect the integrity of the grid, ERCOT says.
ERCOT has initiated blackouts four times: Dec. 22, 1989: 500 MW; April 17, 2006: 1,000 MW; Feb. 2, 2011: 4,000 MW; Feb. 15-18, 2021: 20,000 MW.
ERCOT’s Summer 2022 assessment indicates a low risk (6% probability) of declaring a Level 1 Energy Emergency Alert during peak hours, from 6–8 p.m. The overall daily risk is lower than for Summer 2021, which was at 12% risk.
What is ERCOT doing to prevent rolling blackouts?
The summer is when the Texas power grid reaches peak demand and energy reserves often run low, since air conditioning systems consume lots of electricity. Generally, ERCOT can meet summer demand by planning new power plant additions and grid upgrades in advance, according to Quick Electricity.
With the record-high temperatures Texans are experiencing, that’s creating even more demand than usual, making Texans worry about whether the grid can keep up.
The North American Electric Reliability Corporation, in its 2022 Summer Reliability Assessment, warns that Texas, along with the central and upper Midwest and Southern California, faces an increased risk of power outages this summer from extreme heat, wildfires and extended drought.
“A combination of extreme peak demand, low wind, and high outage rates from thermal generators could require system operators to use emergency procedures, up to and including temporary manual load shedding,” NERC says.
The NERC report cited incidents in May and June 2021 when Texas experienced solar farm shutdowns, which disrupted power plants, interfered with grid recovery operations and caused outages of power units.
Experts at Quick Electricity say ERCOT must do three things to achieve a reliable power supply: forecast energy consumption accurately, have enough power plants and transmission lines to meet demand and keep the grid in optimal condition. That can be done with regular maintenance and grid infrastructure upgrades. Developing an adequate mix of power generation systems is also very important.
ERCOT said Sunday in its appeal for conservation that it continues to use all tools available to manage the grid effectively and reliably, including using reserve power and calling upon large electric customers who have volunteered to lower their energy use.
How to track electricity demand
View daily peak demand forecast, current load, and available generation at http://www.ercot.com.
Follow ERCOT on Twitter (@ERCOT_ISO) and Facebook (Electric Reliability Council of Texas).
Sign up for the ERCOT mobile app (available for download at the Apple App Store and Google Play).
Subscribe to the EmergencyAlerts list on http://lists.ercot.com.
Call Public Utility Commission of Texas Hotline for assistance at 1-888-782-8477
