attract attention in connection with attempts to improve energy security in nations that rely on imported petroleum, but have or can develop large sources of renewable or nuclear electricity, as well as to deal with possible future declines in the amount of petroleum available to import. Because the transport sector uses the energy from petroleum very inefficiently, replacing petroleum with electricity for mobile energy will not require very large investments over many years. Reliability Virtually all devices that operate on electricity are adversely affected by the sudden removal of their power supply. Solutions such as UPS (uninterruptible power supplies) or backup generators are available, but these are expensive. Efficient methods of power storage would allow for devices to have a built-in backup for power cuts, and also reduce the impact of a failure in a generating station. Examples of this are currently available using fuel cells and flywheels. See also Battery electric vehicles Battery-to-grid Cost of electricity by source Distributed generation Energy demand management Energy storage Energy storage as a service (ESaaS) Fuel-cell vehicle Grid-tied electrical system Hybrid electric vehicle Hydrogen economy List of energy storage projects Off-peak Power-to-X Rechargeable battery Solar vehicle Solar-powered boats U.S. Department of Energy International Energy Storage Database, a list of grid energy storage projects Vanadium redox battery, dispatchable grid energy storage Vehicle-to-grid Virtual power plant Wind farm References Saving For a Windless day by Sean Davies in The E&T Magazine Vol 5 Issue 9 from the www.IET.org Further reading External links UK Government report on the Benefits of long-duration electricity storage (Aug 2022) A large grid-connected nickel-cadmium battery Stationary Energy Storage…Key to the Renewable Grid Electricity Storage FactBook Power engineering