In electric power, energy storage: a facility capable of absorbing energy directly from the Grid or Distribution System, or from an RE Plant or from a Conventional Plant connected to the Grid or Distribution System and storing it for a time period, and injecting stored energy when prompted, needed to ensure reliability and balanced power system
ESS technologies shall include, but not limited to:
2.11.1. “ESS Battery Energy Storage System” or “BESS” – capable of storing electric energy electrochemically from which it is able to charge or discharge electric energy;
2.11.2. “Compressed Air Energy Storage” or “CAES” – uses electric energy to inject high-pressure air containers. When energy is required, the pressurized air is heated and expanded in an expansion turbine driving a generator for power production;
2.11.3. “Flywheel Energy Storage” or “FES” – uses electric energy to accelerate a rotating mass, called a “rotor”, to store kinetic energy. Energy is extracted from the system by drawing down the kinetic energy from the rotor; and
2.11.4. “Pumped-Storage Hydropower” or “PSH” – uses electric energy t pump water from a lower elevation reservoir to a higher elevation reservoir. When required, the water flows back from the upper to the lower reservoir, powering a turbine with a generator to produce electric energy [Section 2.11, DOE Department Circular No. DC2023-04-0008, Prescribing the Policy for Energy Storage System in the Electric Power Industry]
In energy resources, hydrogen: a facility capable of absorbing energy directly from the Grid or Distribution System, from an RE Plant, or from a Conventional Plant connected to the Grid or Distribution System, storing it for a period of time, and injecting stored energy when prompted in order to ensure a reliable and balanced power system; ESS technologies shall include, but not be limited to Battery Energy Storage System (BESS), Compressed Air Energy Storage (CAES), Flywheel Energy Storage (FES), and Pumped-Storage Hydropower [Section 4(d), DOE Department Circular No. DC2024-01-0001, Providing a National Policy and General Framework, Roadmap, and Guidelines for the Hydrogen in the Energy Sector]
In renewable energy: a facility capable to absorb and store electric power directly from the Grid or Distribution System, or from an RE Plant or from a Conventional Plant connected to the Grid or Distribution System, and, when prompted by the System Operator, inject the stored electric power into either the Grid or Distribution System, as the case may be, as needed to ensure reliability and balanced power system. ESS technologies include, but are not limited to, Battery Energy Storage System (BESS), Compressed Air Energy Storage (CAES), Flywheel Energy Storage (FES), and Pumped-Storage Hydropower [Section 3(r), Implementing Rules and Regulations of Republic Act No. 9513, as amended by Section 1, DOE Department Circular No. DC2025-09-0014, Prescribing Amendments to Department Circular No. DC2009-05-0008 Titled “Rules and Regulations Implementing Republic Act No. 9513, Otherwise Known as the ‘Renewable Energy Act of 2008’”]