The Distributed Kinetic Energy Recovery System (D-KERS) is the brainchild of Transnet engineer Mr Andreas Pyper and allows the capture and storage of waste energy generated by braking applications on the unpowered axles of freight wagons.

The D-KERS unit is installed inside the bogie which means each wagon can be fitted with up to four units. The Energy Storage Solution (ESS) fitted to the wagon is charged during braking and discharged when applying motoring traction to the axles.

Pyper says D-KERS is not limited to a specific ESS, although a high-speed flywheel is the preferred option because there are no conversion losses and a long service life with almost no degradation.

Simulations based on data for two diesel-operated routes revealed fuel savings of up to 24% could be achieved.

Cash flow analysis shows D-KERS could cover its initial capital cost within five years, or 20-25% of the service life of the unit, with a 30% internal rate of return.