ERCOT & Rotating Outages
ERCOT’s use of Energy Emergency Alerts
Electric Reliability Council of Texas (ERCOT) has a progressive series of emergency procedures that may be used when operating reserves drop below specified levels. These procedures are designed to protect the reliability of the electric system as a whole and prevent an uncontrolled system-wide outage.
Per ERCOT Protocols and North American Electric Reliability Corporation (NERC) requirements, the grid operator is required to declare an Energy Emergency Alert (EEA) when operating reserves drop below 2,300 MW or system frequency cannot be maintained above certain levels and durations. There are three levels of EEA, depending on the amount of operating reserves that are available to meet the electric demand on the system.
When ERCOT issues an EEA, it is able to take advantage of additional resources that are only available during scarcity conditions. Resources include demand response that is procured specifically for these types of conditions (Emergency Response Service and other demand response from Transmission Operators); use of resources that are normally set aside to provide operating reserves (including mandatory load reduction from some industrial facilities); additional generation or imports from neighboring regions; and voluntary conservation by consumers.
If all of the EEA tools listed above are insufficient, rotating outages are required to help preserve the reliability of the system as a whole. However, rotating outages have only been implemented four times in the history of ERCOT.
Energy Emergency Alert Levels
EEA Level 1
When operating reserves drop below 2,300 MW and are not expected to recover within 30 minutes, grid operators can call on all available power supplies, including power from other grids, if available.
EEA Level 2
When operating reserves are less than 1,750 MW and are not expected to recover within 30 minutes, ERCOT can reduce demand on the system by interrupting power from large industrial customers who have contractually agreed to have their electricity turned off during an emergency. ERCOT can also use demand response resources that have been procured to address tight operating conditions.
EEA Level 3
An EEA Level 3 is declared if operating reserves cannot be maintained above 1,375 MW. If conditions do not improve, continue to deteriorate or operating reserves drop below 1,000 MW and are not expected to recover within 30 minutes, ERCOT will order transmission companies to reduce demand on the system.
What is a rotating outage?
Rotating outages are controlled, temporary interruptions of electrical service implemented by utilities to reduce demand and preserve the reliability of the electric system as a whole. Utilities are required to shed load based on their percentage of historic peak demand. Rotating outages are only used as a last resort to bring operating reserves back up to a safe level and maintain system frequency.
Rotating outages primarily affects residential neighborhoods and small businesses. Each transmission company is responsible for determining how they will shed their portion of the load on the system.
ERCOT has initiated system-wide rotating outages four times in the history of ERCOT (Dec. 22, 1989, April 17, 2006, Feb. 2, 2011 and February 15, 2021).
What is a statewide power emergency?
ERCOT issues a Power Emergency, or Energy Emergency Alert Level 3, when there is not enough electric generation available to keep up with consumer demand. When an EEA Level 3 is issued, ERCOT instructs utilities to begin rotating outages according to predetermined emergency curtailment procedures. When ERCOT issues such an order, the Lower Colorado River Authority (LCRA) follows ERCOT’s instructions to reduce power consumption by instituting rolling outages within its service territory.
Why is my power off?
How long will my power be off?
My power was off earlier today or yesterday in a rolling outage. Am I safe for the next one or could it go off again?
Why was my house or business chosen to be part of the outage?
The power outage has caused a life-or-death emergency in my home or business. What do I do?
How often has ERCOT initiated system-wide rotating outages?
ERCOT has instituted system-wide rotating outages four times in the history of ERCOT (Dec. 22, 1989, April 17, 2006, Feb. 2, 2011 and Feb. 16, 2021.)
How can I help conserve power?
You can help by turning off all unnecessary lights and electrical appliances and delaying laundry and other activities that consume electricity. Read other conservation tips from the Public Utility Commission of Texas.