A California utility is seeking permission to have a company build the world’s largest battery, joining a growing list of power companies investing in storing electricity.

Pacific Gas & Electric Co., part of PG&E Corp. , detailed plans for four storage projects totaling nearly 570 megawatts in a Friday filing to regulators, including a 300-megawatt battery installation at a natural-gas-fired power plant owned by Vistra Energy Corp.

That battery, the largest installation of its kind, would be owned by Vistra, and it would be capable of running for four hours while putting out the same amount of power as a small natural gas plant.

In addition, the utility is seeking approval for a 182.5 megawatt system built by Tesla Inc. that would be owned by PG&E, as well two smaller projects. The California Public Utilities Commission must approve the storage projects.

Cost estimates for all of the projects were not immediately available.