Pasadena Begins Construction on First Utility-Scale Battery at Glenarm
The 25-megawatt project is expected to begin operating in 2027, bringing new energy storage capacity to Pasadena as questions about cost and safety remain part of the public conversation.
Pasadena Water and Power is building the city’s first utility-scale battery energy storage system at the Glenarm Power Plant in southern Pasadena, a major investment designed to store electricity during the day and make it available when demand rises in the evening.
Construction began in September 2026, and city and state officials gathered for a ceremonial kickoff on October 7. The 25-megawatt project is expected to be completed by summer 2027.
For Pasadena, the battery represents another step toward the city’s goal of obtaining 100% of its electricity from carbon-free sources by the end of 2030. But the project also raises important questions about cost, ownership, emergency preparedness, and its proximity to a local school.
How Pasadena’s New Battery Will Work
The Glenarm Battery Energy Storage System, known as Glenarm BESS, will use lithium iron phosphate batteries capable of delivering up to 25 megawatts of electricity for approximately four hours. That represents 100 megawatt-hours of nominal energy storage capacity.
The concept addresses a challenge facing utilities that increasingly rely on solar power.
Solar generation is generally strongest during daylight hours, but electricity demand often remains high after sunset. Instead of allowing available solar generation to go unused, battery storage can absorb that electricity and release it when customers need it.
Pasadena Water and Power says the project will also improve flexibility and reliability during extreme events and could help restore service following a widespread power system shutdown.
The battery will not generate electricity on its own. Its value comes from storing electricity and making it available at a more useful time.
At the October 7 ceremony, Pasadena Water and Power General Manager David Reyes said the utility is using new technologies to “strengthen and expand the solar investments already serving our community.”
State Senator Sasha Renée Pérez and Assemblymember John Harabedian joined Mayor Victor Gordo, Councilmember Jason Lyon, Interim City Manager Matthew E. Hawkesworth, and utility officials at the event.
A Small Site Near Blair School
The battery will occupy approximately 0.59 acres within the existing Glenarm Power Plant complex. The city’s final environmental documents identify the project site as 72 East Glenarm Street, near the Arroyo Seco Parkway.
The location has drawn attention because of its proximity to Blair School.
According to the city’s environmental review, Blair’s middle and high school campuses are approximately 455 feet east of the project site.
Former Pasadena Mayor William Paparian raised concerns about that proximity in a June 21, 2026 letter to the City Council.
Paparian urged additional environmental and financial analysis before the city awarded its construction contract. His concerns included the potential for battery fires, toxic gas emissions, emergency response planning, and long-term costs associated with battery replacement and disposal.
He also called for an independent safety and lifecycle cost review.
The city had previously completed its environmental review. On March 19, 2025, a Pasadena hearing officer approved the project’s conditional use permit and adopted a Mitigated Negative Declaration, concluding that potentially significant environmental impacts could be reduced to less-than-significant levels through required mitigation measures.
Those measures include an emergency response and action plan developed with Pasadena Water and Power and approved by the Pasadena Fire Department.
The plan must address fire detection, emergency procedures, evacuation planning, and public communication. It also calls for coordination with nearby schools, businesses, residents, and transportation agencies.
The City’s environmental documents recognize that battery systems can present fire and toxic gas risks. The determination was that those risks could be mitigated, not that they were impossible.
The City Council subsequently approved the construction contract on June 22, 2026.
What Will the Glenarm Battery Cost?
The project’s financial structure involves more than one agreement.
In June 2024, the Pasadena City Council authorized a 15-year energy storage service agreement with Glenarm BESS LLC. The agreement establishes a service rate of $12.18 per kilowatt per month, with a total contract ceiling of $55.31 million, including contingency funds.
That agreement is separate from the construction contract.
On June 22, 2026, the council approved a construction contract with Baker Electric & Renewables LLC for up to $8.39 million, including contingency funds.
Pasadena Water and Power has also received a $9.66 million grant through the California Energy Commission’s Distributed Electricity Backup Assets program to help offset eligible construction expenses.
The arrangement gives Pasadena access to the storage system without requiring the city to purchase the battery equipment immediately.
Glenarm BESS LLC was originally established by San Jose-based EPC Energy Inc. In December 2025, the City Council considered and approved agreements associated with a change of control after Infinite Grid Capital LLC acquired full ownership of Glenarm BESS LLC.
The city retains ownership of the land, while the private project company is responsible for owning and operating the battery under the storage agreement unless Pasadena exercises a purchase option.
The original agreement included an estimated purchase price of approximately $47.1 million if the city acquired the system when commercial operations began, with lower prices available later in the contract term. That figure dates to 2024 and should not be interpreted as an updated purchase quote.
If Pasadena purchases the facility, the monthly storage service payments would stop under the agreement.
For electricity customers, Pasadena Water and Power estimated in 2024 that the project’s incremental effect on the average electric system rate would be approximately 0.32 cents per kilowatt-hour.
That projection assumed other rate components remained unchanged. It was not a comprehensive forecast of future electricity bills.
Why the Project Matters for Pasadena’s Energy Future
The battery arrives during a broader transition in Pasadena’s electricity supply.
Pasadena Water and Power plans to end its participation in the Intermountain Power Project in Utah in June 2027. The utility has been planning a mix of replacement resources, including renewable energy purchases and local energy storage, to maintain reliability while reducing dependence on carbon-emitting electricity.
The Glenarm battery is one part of that strategy, not a complete replacement for the city’s existing power resources.
Locating storage within Pasadena’s own electrical system also gives the utility more direct operating flexibility as it adds renewable energy and prepares for changing electricity demand.
What Residents Can Expect Next
Pasadena Water and Power says construction will generally take place on weekdays between 7 a.m. and 5 p.m., with efforts to limit disruptions to surrounding streets, residences, and businesses.
The utility currently expects the battery to be completed in summer 2027.
For residents, the project’s long-term significance will come down to several questions: whether it improves reliability as planned, whether it delivers the expected financial value, and how effectively its safety requirements are implemented.
For now, a relatively small section of the historic Glenarm Power Plant is becoming part of a much larger effort to reshape how Pasadena stores and uses electricity.
FAQ’s
When will Pasadena’s Glenarm battery begin operating?
Pasadena Water and Power currently expects the 25-megawatt Glenarm battery system to be completed in summer 2027. A specific commercial operation date has not been confirmed.
How much electricity can the Glenarm battery store?
The system is designed to deliver up to 25 megawatts for approximately four hours, equivalent to 100 megawatt-hours of nominal storage capacity.
How close is the Glenarm battery to Blair School?
The City of Pasadena’s environmental review identifies Blair’s middle and high school campuses approximately 455 feet east of the battery project site. The project is subject to fire safety and emergency response planning requirements.
Sources
1. “City of Pasadena, October 8, 2026 construction kickoff announcement” (https://www.cityofpasadena.net/city-manager/news/state-officials-join-pasadena-water-and-power-to-kickoff-construction-of-glenarm-battery-energy-storage-system/)
2. “Pasadena Water and Power, Glenarm Battery Energy Storage System project information” (https://pwp.cityofpasadena.net/glenarm-battery-energy-storage-system-bess/)
3. “Pasadena City Council, June 17, 2024 energy storage agreement report” (https://ww2.cityofpasadena.net/2024%20Agendas/Jun-17_24/AR%2012.pdf)
4. “Pasadena City Council, December 8, 2025 ownership and financing report” (https://ww2.cityofpasadena.net/2025%20Agendas/Dec_08_25/AR%201.pdf)
5. “Pasadena City Council, June 22, 2026 construction contract report” (https://ww2.cityofpasadena.net/2026%20Agendas/Jun_22_26/AR%205.pdf)
6. “City of Pasadena, Glenarm environmental review and responses to public comments” (https://www.cityofpasadena.net/planning/wp-content/uploads/sites/30/Glenarm-BESS-Project-Response-to-Comments.pdf)
7. “City of Pasadena, Glenarm mitigation monitoring and reporting program” (https://www.cityofpasadena.net/planning/wp-content/uploads/sites/30/Glenarm-BESS-Project-Mitigation-Monitoring-and-Reporting-Program.pdf)
8. “William Paparian’s June 21, 2026 letter, included in official City Council correspondence” (https://ww2.cityofpasadena.net/2026%20Agendas/Jun_22_26/AR%205%20SUPP%20CORR.pdf)