GERMANY: Mannheim tram operator MVV and Bombardier have completed four years of trials with a Mitrac Energy Saver which uses double-layer capacitors to store regenerated braking energy (RG 7.06 p405).

Long-term results showed that the tram's traction power consumption was reduced by 30%. Overall power needs including doors, air-conditioning and lighting were cut by a total of 20%, and the long-term reliability of the technology has now been demonstrated. The capacitors also enabled the vehicle to run with its pantograph lowered, and during testing the 1 kW/h capacitor unit was able to power the tram over 500 m making multiple stops.

The SuperCap package has now been removed for an assessment of how production trams will have the roof-mounted equipment integrated into the vehicle design. The test tram remains in service as a conventional vehicle.

As a result of the successful trials, Rhein-Neckar-Verkehr has decided to include the SuperCap system on 19 trams ordered last October under a €52m option on a 1998 contract. They have been ordered at the instigation of the city of Heidelberg, which wishes to avoid erecting wires through a university campus on a planned extension to Neuenheimer Feld. The city expects that the additional €270 000 cost per vehicle will be recovered over the first 15 years of the vehicle life.

According to Bombardier, negotiations are now underway with other operators.