ExxonMobil took its Joliet, Illinois, refinery out of service after a power interruption triggered safety systems and a general shutdown of the facility.
Power supply was lost around 3:30 PM on Sunday, September 13, and was restored near 7:00 PM, but the refinery remained out of operation while its units were being stabilized.
The facility has a processing capacity of approximately 264,000 barrels per day and can produce nearly 11 million gallons per day of gasoline and diesel, fuels that are primarily distributed in the U.S. Midwest.
ExxonMobil continues to assess the plant’s condition and investigate the cause of the power interruption. IIR Energy estimates that operations could normalize by the end of this week.
When electricity becomes a process variable
In a modern refinery, electricity is not merely an auxiliary service. It powers motors, pumps, compressors, control systems, instrumentation, and other equipment essential for maintaining processes within their operating conditions. Therefore, a loss of supply can trigger a sequence of protections and trips that end up affecting multiple units simultaneously.
That is precisely what happened at Joliet. The interruption activated the safety flare, the flare system designed to manage hydrocarbons and gases in a controlled manner during abnormal conditions, and the facility subsequently experienced a general shutdown.
The presence of the flare, therefore, should not be interpreted simply as a visual sign of the incident: it is part of the refinery’s safety response to a process disturbance.
The episode shows why electrical reliability is part of process reliability. Refining infrastructure functions as an integrated electromechanical system: when an essential condition disappears, protection systems can remove equipment from service to prevent an electrical disturbance from evolving into mechanical damage, overpressure, or unsafe conditions.
Restoring power does not mean restarting the plant
Power supply returned approximately three and a half hours after the incident, but production did not recover immediately. This difference is technically significant.
A refinery cannot be treated as a facility that simply turns back on after a blackout. Following a general shutdown, units must be stabilized, equipment conditions checked, auxiliary services restored, and the necessary conditions progressively recovered to reintroduce feedstock and bring each process back to its operating regime.
Exxon itself noted that it was assessing the facility’s status, while IIR Energy reported that the units were in the process of stabilization. The precedent also demonstrates that the duration of the electrical event and the duration of the industrial shutdown can be very different: in 2024, another power interruption left multiple Joliet units out of service for several days.
For reliability engineering, this difference is fundamental. The recovery time of a complex facility can become a more important indicator than the duration of the failure that caused the shutdown.
ExxonMobil: 264,000 bpd temporarily taken out of the circuit
The industrial scale of Joliet explains why a localized disturbance can transcend the plant’s boundaries.
ExxonMobil indicates that the refinery can process up to 275,000 barrels of crude per day in its current configuration, while Reuters reported a capacity of approximately 264,000 bpd for this incident. The facility produces around 11 million gallons per day of gasoline and diesel and supplies Midwest markets.
The potential effect gains greater relevance because the U.S. fuel market is currently experiencing a tight supply situation. Reuters reported that the national average price of diesel exceeded $6 per gallon last week, while international disruptions and exports maintain pressure on domestic inventories.
Additionally, local reports indicate that gasoline prices in Chicago began to increase while Joliet remained out of operation, although it is still too early to attribute any regional movement exclusively to the ExxonMobil shutdown.
SOURCE: https://www.reuters.com/
PHOTO: ExxonMobil
