A proposal by Pacific Gas & Electric (PG&E), one of California’s three main investor-owned utilities (IOUs) to deploy large-scale energy storage to replace peaking natural gas plants has been approved by the state’s regulator.

Last week, the California Public Utilities Commission (CPUC) issued its approval of three capacity contracts and one power purchase agreement (PPA) for 567.5MW of energy storage capacity to be built across four large-scale battery storage systems. Significantly, each will store energy for four hours, making them viable capacity resources to replace gas plants.

PG&E submitted its proposal to the commission in late June and said the selected projects had been awarded from more than 100 options from around 30 submitted proposals with the solicitation launched to address local voltage issues as well as capacity deficiencies in specific sub-areas of the utility’s service area.

As reported by Energy-Storage.news at that time, the winning projects will be delivered by Dynegy-Vistra Energy, Hummingbird Energy Storage LLC, Micronoc Inc and Tesla.

The two largest are the Dynegy-Vistra project (300MW / 1,200MWh) and the Tesla (182.5MW / 730MWh). PG&E will own and operate the Tesla system, while capacity from the other three will be purchased by the utility through the aforementioned capacity agreements.

Read more: Energy Storage News