MISO initiated an hourslong load shedding event in greater New Orleans over Memorial Day weekend with nuclear power outages appearing to play a role.
The RTO said on X that it ordered Entergy and Cleco to drop about 600 MW on the evening of May 25 to “maintain the reliability of the bulk electric system.”
“High temperatures in Louisiana led to higher-than-expected demand, and with planned and unplanned transmission and generation outages, MISO needed to take this action as a very last resort. MISO is coordinating closely with Entergy and Cleco to restore power as quickly as possible,” MISO wrote at the time.
Entergy New Orleans and Entergy Louisiana reported they initiated the rolling blackouts on MISO’s orders around 5 p.m. CT. Entergy said the “last resort” actions were to “prevent a more extensive, prolonged power outage that could severely affect the reliability of the power grid.”
“MISO is directing actions to be taken to restore the system to normal operations as quickly as possible and will direct Entergy to stop these outages as soon as the power shortfall no longer threatens the integrity of the rest of the electrical power system,” Entergy said in a press release at the time. Later that day, the utility issued a second release announcing MISO canceled further periodic load shed. Entergy said it would work with MISO to understand the sudden load shed directive.
Local news outlets reported that more than 100,000 customers around New Orleans were impacted by the controlled outages. Entergy said it restored power around 8 p.m. CT. Entergy and Cleco’s territories in Orleans, Jefferson, St. Tammany, St. Bernard and Plaquemines parishes reportedly were affected.
Cleco also confirmed it instituted rolling outages on MISO’s instructions.
“If the power supply cannot meet the demand, periodic power outages could be needed to protect the stability of the power grid and prevent widespread lengthy outages,” said Jennifer Cahill, director of corporate communications. “This was the case yesterday when we took the unprecedented step, as directed by MISO, to force outages to some customers in St. Tammany Parish.”
In a statement to RTO Insider, MISO again emphasized the temporary, periodic outages were its only remaining option to maintain reliability in MISO South. The grid operator did not disclose additional information on the incident.
“We will conduct a thorough assessment of the event and provide additional information once complete,” MISO spokesperson Brandon Morris said.
MISO’s real-time market notifications don’t list any emergency steps that might have preceded the event.
The outage could be the result of hot weather and nuclear power unexpectedly going offline. Entergy declined to comment on whether the nuclear outages contributed to demand exceeding supply.
But Louisiana Public Service Commissioner Davante Lewis said Entergy’s 974-MW River Bend Nuclear Station in St. Francisville, La., tripped offline May 25 as Entergy attempted to restore it to service. The unexpected outage reportedly occurred at the same time Entergy’s Waterford nuclear plant in Killona, La., was on a scheduled outage. The Nuclear Regulatory Commission listed both reactors as offline before the holiday weekend.
Meanwhile, temperatures around New Orleans registered at about 90 degrees Fahrenheit.
Lewis told local station WWL-TV that the simultaneous scheduled and unscheduled outages should not have risen to a load shedding event. “That means there’s more to the story — either bad forecasting, bad modeling or higher demand than was projected,” he said.
Fellow Commissioner Eric Skrmetta said the load-shed orders arrived less than three minutes before action was required so utilities didn’t have the option to cut interruptible industrial customers first in an attempt to reduce demand. He said the notification time was “unacceptable” and said upcoming commission meetings would focus on appropriate notification times from RTOs before delivering load shed instructions.
Until now, MISO had directed load shedding just once in the past 17 years, ordering about 700 MW offline in MISO South during Winter Storm Uri in early 2021.
