In Escondido, a city in San Diego County not far from San Diego itself, the utility SDG&E, in partnership with the Virginia-based company AES Energy Storage, recently unveiled a California milestone: the largest lithium-ion energy storage installation in the world. The 30 megawatt (MW) facility contains 400,000 AES Advancion® batteries, similar to ones found in electric vehicles. The batteries are installed in nearly 20,000 modules and placed in 24 containers. In addition, the Escondido facility is alleged to be 50 percent larger than the next-largest such installation. The same utility also just launched a smaller energy storage facility of 7.5 MW at El Cajon, California. Thus, the two arrays combined provide 37.5 MW of power and can service 25,000 homes with power for four hours. They can also serve as a 75 MW flexible resource to the grid.
As a SDG&E press release asserts, the facility “will provide reliable energy when customers need it most, and maximize the use of renewable resources such as solar and wind.” Josh Gerber, Project Director at SDG&E, said at the launching of the installation, “On a day [like this], which is nice and sunny, but also cool, demands for energy in the middle of the day aren’t very high but production is. So we’d be storing solar in the day and releasing it at 6:00–7:00 tonight after everyone’s home from work and school and home with their families. It’s a tool that we can use to make the integration of solar and wind much more reliable and better matched to the times when our customers need it most.”
Unusually, the project took only about six months to come online, rather than the customary timeline of a year or more. In October 2015, a methane leak occurred at the Aliso Canyon gas storage facility outside Los Angeles, considered the worst such leak in U.S. history. The facility was shut down, which reduced fuel supplies for area power plants. The California Public Utilities Commission (CPUC) responded by ordering Southern California investor-owned utilities (IOUs) to fast-track additional energy storage options to maintain energy reliability. As it happened, a previous CPUC order compelled the utility to procure 165 MW of energy storage in its service territory by 2020. Thus, SDG&E was already looking into energy storage when the order that resulted from the methane leak was issued.
“We had gone through an evaluation of firm bids from AES and others and that actually started about 10 days before the [Aliso Canyon] resolution came out,” Randy Nicholson, SDG&E’s policy manager for advanced technology, said. “So we were getting to know each other really well when the resolution hit and that allowed us to move really quickly.”
The agreement between SDG&E and AES was reached in August 2016. However, when the online publication Utility Dive visited the site in October 2016, it was little more than an empty lot adjacent to a substation with some wooden frames constructed on it. By mid-November, however, construction was well underway at Escondido, and the site was completely ready for the launch in late February. The gas crisis and the speedy installation of the Escondido facility, according to some executives, may help prove that energy storage can serve the needs of the power system, potentially replacing natural gas peaker plants.
“It’s a little too early to tell if storage is going to replace all peakers going forward,” Nicholson said. “This project in particular is going to help us answer that question, to determine whether, going forward, if you want to start moving the mix in another direction.”
Most utility-scale batteries in the U.S. are utilized for shorter storage functions, such as frequency response. Brian Perusse, vice president for international market development at AES, said that AES perceives this project as an “inflection point,” not just for bigger batteries, but for ones of long duration, four to six hours, like the ones at Escondido.
Said Perusse, “A lot of people have been saying the same thing… it’s a four to six hour duration product to help serve the peak and improve reliability and it’s the first project of its size. You said four hours is coming? It’s here. So that’s really changed.”
Photo by SDG&E.