Warship Technology: January 2020
A flywheel-based energy storage system based on Le Mans motor sport technology has been developed by GKN and DSTL to demonstrate an energy storage option for the Royal Navy. The project has demonstrated the ability to manage the energy demands of novel future capabilities such as the Dragonfire Laser Directed Energy Weapon (LDEW), which is being developed by DSTL and industry.
The Flywheel Energy Storage System (FESS) uses innovative high-speed and lightweight flywheels to provide high-power electrical pulses that future systems such as Dragonfire will require, reducing the impact of these systems to the rest of the ship, while avoiding the widely reported safety concern around battery-based systems.
The electrical demand profile of LDEW-like systems is a high-power pulse load. This has implications for the operation of naval power systems, specifically related to the capability of the system to supply the LDEW while maintaining continuous supply to the rest of the power system on a vessel.
A flywheel installed on a naval platform might support this kind of high power pulse load demand, but the LDEW is not the only type of high power pulse load expected to be retrofitted to existing and future naval power systems. Other equipment that may have a similar load characteristic include rail guns, ballistic missile defence sensors, future electronic warfare systems and electromagnetic unmanned aerial vehicle launchers.
Flywheel energy storage lends itself to high power applications over a short duration, in the order of seconds or milliseconds. In comparison to other energy storage technologies, flywheels can be considered as operating between capacitor and chemical cell technologies, providing higher power than chemical cells and longer duration than capacitor technologies.
This ‘mid-location’ in the energy storage spectrum makes them suited to applications like the LDEW.
Other attributes associated with flywheels that make them suited to naval applications include the fact that they need minimal routine maintenance compared to chemical cell technologies and the fact that they are not degraded by environment, depth of charge, or number of use cycles in the way that cell technologies can be. They can also be completely turned off with no residual charge during periods when they are not required, such as during peacetime operation, and are modular self-contained units for capacity scaling, redundancy, and for containing mechanical failures.
