Typical energy storage capacity compared to typical discharge duration for various geologic and nongeologic energy storage methods

Figure 3 from USGS Fact Sheet 2022-3082. Graph of typical energy storage capacity compared to typical discharge duration for various geologic and nongeologic energy storage methods. Oval sizes are estimated based on current technology. Modified from Crotogino and others (2017) and Matos and others (2019). Btu, British thermal unit.

Energy production and consumption in the United States is undergoing a transition from primarily fossil fuels to a mixture that includes greater shares of renewable sources and nuclear energy. Battery storage installations have a short start-up time to deliver power along with relatively short duration and small capacity. In comparison, geologic energy storage methods can retain vastly greater quantities of energy over much longer time periods (fig. 3), although power start-up times are not as fast (Aneke and Wang, 2016). An electrical grid that uses long duration energy storage projects with over 100 hours of stored power could result in the greatest reduction in electricity costs (Sepulveda and others, 2021). Geologic energy storage is a practical solution that can store 100 or more hours of energy. Batteries are primarily designed for storing electrical energy, but geologic storage methods have an advantage of being able to store chemical and thermal energy (for space heating, for example) directly without conversion to electricity. In addition, chemical and thermal energy storage would not depend on critical minerals used in batteries, which may be in short supply. All these characteristics make geologic energy storage an important approach for an energy transition in the United States.