The Digital Displacement Rail Transmission with Flywheel Energy Storage project, which will commence in the second half of this year, aims to provide an environmentally-friendly regenerative braking solution combined with an onboard mechanical energy storage system that will save fuel and reduce costs.

The system will be first rail application of the Artemis Digital Displacement hydraulic pump-motor and Ricardo’s Kinergy flywjeel high-energy density storage system, which is already being evaluated in commercial bus operations. The rail solution is intended to be retrofitted to existing rolling stock as well as new vehicles. Bombardier will provide a wheelset for the testing programme, which will take place on a dynamometer rig at Artmesis’ facility near Edinburgh. A follow up programme is anticipated during which the system will be installed and tested on an operating train.

The consortium says that the new system will be designed to suit various operating philosophies including alteration of the engine demand enabling closer operation to optimum brake-specific fuel consumption, saving fuel and reducing CO₂ emissions. The system may also be configured to use stored energy to augment the peak acceleration of the train, increasing the operational flexibility of older rolling stock.