Nearly 1.3 million electric customers in the Baltimore Gas and Electric Company (BGE)—a member of PJM Interconnection (PJM), a subsidiary of Exelon Corporation, and the largest electric and natural gas utility in Central Maryland—territory were bracing for a blackout, after the transmission facility in Anne Arundel County serving the coal-fired Brandon Shores and oil-burning H.A. Wagner power plants—owned by Talen Energy—failed in the early hours on August 4, 2025. Though, in the end, only an estimated 4,000 customers in Howard County were without power for around 30 minutes.
At 3:52 pm, electricity demand briefly exceeded the current capacity of the local transmission system, according to PJM Interconnection, which runs the utility grid serving Maryland. So PJM gave BGE a load shed directive to help reduce electricity flow on overloaded lines. Shortly after the directive, BGE reported that the portions of the transmission system that were inoperable for most of the day had been restored. PJM cancelled the directive 30 minutes later, as they were able to bring enough power into the Baltimore area.
The local power plants experiencing an unplanned disconnection from the BGE electric system, caused the outage. This led to Brandon Shores Units 1 and 2 automatically shutting down. Wagner’s two units and Brandon Shores Unit 2 could only start producing electricity again once they went through the start-up process, if PJM Interconnection, the region’s grid operator, requested it.
By the same evening, BGE asked its customers to conserve power by taking steps such as turning off nonessential appliances and using less air-conditioning, including by closing their blinds and turning on ceiling fans. It also urged ratepayers to set aside supplies of food and water, and charge critical electronic devices, in case a larger outage took place.
The Brandon Shores and Wagner plants were scheduled to shut down in May 2025. But amid rising demand for power, regulators compelled the facilities to stay open through May 2029 using a “reliability must-run” agreement. Ratepayers are footing the $180 million annual bill. The Maryland Office of People’s Counsel has argued that ratepayers are essentially paying twice for the must-run agreement, since the two plants were excluded from a key energy auction held in 2024, raising prices considerably. The People’s Counsel is pushing federal regulators to return $5 billion in auction proceeds to customers as a result.
The first of Brandon Shores’ units cannot contribute power to the grid until BGE repairs the infrastructure, though the second unit was available for power generation upon completion of the start-up process in the afternoon. The same was true for the nearby Wagner plant, which is served by the same transmission infrastructure.
An internal investigation into the Brandon Shores plant disconnection is underway. Such ‘trip’ events can be caused by transformer overloads, weather damage, human error, or generation units falling out of sync with the grid — but are especially disruptive when grid capacity is already tight.
BGE has electric customers in Baltimore City, in Baltimore, Harford, Carroll, Howard and Anne Arundel counties, and parts of Montgomery and Prince George’s counties. The affected BGE substation has been repaired, though continued reliable operation of the local transmission system will depend upon the operability of the transmission facilities that tripped.