Flywheels store energy as kinetic motion in a massive rotor; a flywheel is basically a large “kinetic battery”. Flywheels use motor-generators to accelerate their rotors at very high speeds to store or generate electricity on demand. The rotor spins in a vacuum and hovers on magnetic bearings to reduce friction and maximize round trip system efficiency.
Battery energy storage systems use chemical reactions to store and generate electricity. There are a variety of commercial batteries available in the market today that are capable of providing grid-scale services. Traditional batteries are typically comprised of two metal terminals (electrodes), an anode and a cathode, where chemical reactions take place. Electrolytic material allows for the flow of electrical charge between the terminals. Some types of batteries that are in use today include:
- Lithium ion
- Lead acid
- Sodium sulphur
- Sodium nickel chloride
Flow batteries use redox (chemical oxidation and reduction) reactions to store energy. Unlike solid state batteries, flow batteries pump charged electrolytic material through a closed circuit. The electrolyte from one tank is pumped past electrolyte from another tank. Redox reactions occur at a specially designed membrane that allows electrical charge to move between analytic and catholytic material to store energy.
Compressed Air Technology
Compressed air energy storage (CAES) technologies store energy as pressure and heat in underground reservoirs. When air is compressed, a substantial amount of heat is generated and, if not captured, this heat and associated energy is lost. Conversely, when compressed air is expanded a substantial amount of heat must be added to retain the potential energy released during the expansion. In traditional compressed air energy storage projects, the heat generated during compression is released into the atmosphere and the compressed air is released through a gas turbine. Heat is then reintroduced through the burning of natural gas and the reheated air is used to drive a turbine. NRStor is working with technology suppliers that have invented and developed CAES technology which can capture heat and eliminate the need for any additional fuel. This process allows for a highly efficient system that requires no natural gas and produces zero carbon emissions.