The U.S. Energy Information Administration’s (EIA) latest inventory of electric generators shows that the number of solar and wind generation sites co-located with batteries has grown from 19 paired sites in 2016 to 53 paired sites in 2019.
The trend is expected to continue: according to planned installations reported to EIA, another 56 facilities pairing renewable energy and battery storage will come online by the end of 2023.
Combining energy storage with renewable technologies such as wind and solar provides several benefits such as the ability to store energy as it is generated and then redistribute it when needed, rather than as it is produced. This ability reduces the need to limit renewable generation and allows the energy to be deployed during periods of high electricity demand.
The most commonly reported application for batteries co-located with renewable sources is storing excess energy, however the majority of batteries are multi-functional. Frequency regulation is the second-most common use for these batteries. Frequency regulation helps maintain the grid’s electric frequency on a second-to-second basis. Batteries can also provide transmission and distribution support, helping to smooth out energy flows.
More than 90% of the total operating hybrid capacity the United States is located in only nine states. Texas alone has 46% of the current total. Hybrid capacity in the U.S. is concentrated at a few large sites. Ten facilities account for more than half of the total operational capacity.
EIA notes that although nearly 25% of total U.S. battery capacity is installed as part of a hybrid system, only 1% of total wind capacity and 2% of total solar capacity is part of a hybrid system.
Reported data show that future projects will be much larger in scale than currently operating projects. A project in Nevada, Gemini Solar, is expected to add more than one gigawatt of combined renewable and storage capacity.
The U.S. Department of the Interior approved the Gemini Solar project on May 11, 2020, and the first phase of construction is expected to begin in 2021.
In approving the project, the Trump Administration said the Gemini Solar project would be the largest solar project in United States history. U.S. Secretary of the Interior David Bernhardt signed the Record of Decision (ROD) for Solar Partners XI, LLC to construct a 690-MW photovoltaic solar electric generating facility and ancillary facilities about 30 miles northeast of Las Vegas. The estimated $1 billion Gemini Solar Project could be the eighth-largest solar power facility in the world when finished.
The project has a 25-year power purchase agreement with investor-owned NV Energy. The project will include an onsite substation that will connect to NV Energy’s transmission facility located near the site and a 380-MW solar-powered battery system able to store and deploy over 1,400 megawatt hours.
By the end of 2023, average renewable capacity at proposed U.S. facilities is expected to grow from 34 megawatts (MW) to 75 MW, and average battery capacity will grow from 5 MW to 36 MW, EIA said in its report.
Pairing wind and solar power with battery storage can result in cost savings and fetch premiums in wholesale power markets, but those premiums could potentially be higher for generation and storage facilities that are not co-located, according to a recent report from Lawrence Berkeley National Laboratory.
Public power utilities pursue solar plus storage projects
Several public power utilities have pursued solar plus storage projects.
The Los Angeles Department of Water and Power Board of Commissioners in September unanimously voted to approve power purchase agreements for the Eland Solar and Storage Center.
In November, Arizona public power utility Salt River Project announced investments in two new solar energy plus battery storage plants.
And in December the Glendale, Calif., City Council adopted a resolution to enter into a 25-year power sales agreement with the Southern California Public Power Authority for a 12.5% share of the renewable solar energy, battery energy storage products, and associated environmental attributes from the Eland 1 Solar and Storage Center in Kern County, Calif.