Battery storage for renewable energy is becoming more important in California, although most projects, so far, are small. Battery technology allows the capture and storage of energy during times of reduced demand for use during times of high demand. That saves costs for the user when supply is low, for example, when the sun is not out or the wind does not blow.

On Dec. 1 Pacific Gas & Electric Co. filed plans withe California Public Utilities Commission to buy stored power from six new projects totaling 165 megawatts.

One of those is a new 50-megawatt battery storage project in Fresno that would be one of the state’s largest stand-alone lithium ion facilities.

PG&E plans to buy battery storage power to be delivered back to the grid during times of peak demand when its system is congested.

The utility has an agreement to connect to three facilities in this part of the state, all located in Central and Northern California, including the largest one in the Fresno area. That is the 50-megawatt Kingston project.

All three are owned by Enel, an Italian energy firm.

Also contracted will be the 25-megawatt Cascade project in Stockton and the 10-megawatt Sierra project in Jamestown.

The projects are developed with Sovereign Energy Storage, an independent developer of large-scale utility battery energy storage projects, and are expected to be operational by 2023, pending review and approval by the California Public Utility Commission as well as local and regulatory agencies.

The three projects will contribute to the expansion of Enel’s energy storage portfolio, which includes both stand-alone battery storage systems as well as projects combining storage with both thermal and renewable sources.

The California Public Utility Commission has a stated goal of adding 1.3 gigawatts of energy storage by 2024.

Storage plays an increasingly important role for California energy companies as they work to achieve the state’s ambitious clean energy goals. By the end of 2017, PG&E forecasts that about 33 percent of its retail electric deliveries will come from renewable sources. Energy storage will help integrate many of those resources, such as wind and solar, which are intermittent or provide peak output during times of low demand.

Energy storage has been a part of PG&E’s power mix for decades, starting with the Helm Hydro-Electric Facility and continuing with pilot projects such as the 2-megawatt Battery Storage Pilot at the Vacaville Substation and the 4-megawatt Yerba Buena Battery Energy Storage System located on the property of Silicon Valley storage technology company HGST.

Battery storage gained notoriety when California suffered the worst natural-gas leak in U.S. history, resulting in a low volume of gas for peak power generation around Los Angeles and San Diego. Responding to the emergency, the state deployed 100 megawatts of storage at several sites in only six months, developed by Tesla.