Pairing renewable energy generators with energy storage, particularly batteries, is increasingly common as the cost of energy storage continues to decrease. 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. This 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 a variety of benefits. One of the most critical is 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 curtail renewable generation and allows the energy to be deployed during periods of high electricity demand.
Although the most commonly reported application for batteries co-located with renewable sources is storing excess energy, the majority of batteries serve more than one function. Frequency regulation, which helps maintain the grid’s electric frequency on a second-to-second basis, is the second-most common use for batteries co-located with renewables. Batteries can also provide transmission and distribution support, helping to smooth out energy flows. The ability to support the integration of renewables into the grid’s current infrastructure, in addition to other ancillary services that they perform such as frequency regulation, are primary drivers in the growth of battery-renewable pairings.
Currently, more than 90% of the total operating hybrid (renewable generator plus energy storage) capacity in the country is located in just nine states. Texas alone has 46% of the current total. Hybrid capacity in the United States is concentrated at a few large sites, and 10 facilities account for more than half of total operational capacity. Installation as part of a hybrid system is common for batteries but not for renewable generators such as wind and solar. 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. One anticipated projected in Nevada called 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. By the end of 2023, average renewable capacity at proposed U.S. facilities will more than double from 34 megawatts (MW) to 75 MW, and average battery capacity will grow from 5 MW to 36 MW.
Principal contributors: Maxwell Hayes, Sara Hoff