Nova Power Bank
Nova Power Bank / MenifeeCA
How do you turn a decommissioned gas plant into one of the largest energy storage projects in the world?

Mortenson was chosen as the Engineering, Procurement, Construction (EPC) contractor for both the battery storage and substation scopes for Calpine Corporation’s Nova Power Bank energy storage project in Menifee, California. The 680-megawatt project, slated to be one of the largest in the industry, is being built on the site of a decommissioned gas plant. 

Previously known as the Inland Empire Energy Center, the natural gas-fired generators were decommissioned and removed so the site can be transformed into an energy storage project. Major portions of the existing facility, including foundations, structures, and electrical infrastructure are contributing to a highly sustainable transformation which will better serve the state’s peak power demand. 

The project is a facility that will provide instantaneous, flexible power and grid reliability for the people of California. Repurposing existing assets comes with design and construction challenges but is a responsible and effective way to bring energy storage to those that can benefit from it the most. 

The site uses more than 1000 BYD Cube Pro battery enclosures which will be connected to Southern California Edison through three 500kV substations on site. The project can power as many as 680,000 California homes for four hours. 

At peak, nearly 200 union craftworkers have been on site, including members of IBEW Local 440, Operators local 12, LIUNA local 1184, Ironworkers local 433, Lineman local 47, and Carpenters local 951. 

The project is performing multiple community engagement activities throughout the life of the project, including donations to multiple local charities. 

Construction for the project began in May 2023 with phased turnovers starting less than 12 months after breaking ground. The first phases of the project are coming online in 2024 and is expected to be fully completed in 2025. 

Facts And Figures

680 megawatts energy storage

3x 500kV substations 

Completion: 2025

Delivery Methods


The Team