Sustainability is also a top priority in the Netherlands. The expansion of lines through new residential areas and the resulting increase in electricity demand pose a particular challenge for the Rotterdam transport operator RET.

Kruch is part of a small tram sensation! 

Rotterdam’s public transport operator RET (Rotterdamse Elektrische Tram) is currently testing a “power bank”, a kind of large energy storage unit that stores the energy generated when the trams brake and makes it available for reuse. 

These improvements could only be calculated and modelled using Kruch’s energy flow simulation (EFS) measurements. This allowed meaningful data to be collected, demonstrating the efficient use of braking energy by the Power Bank. As a result, RET was able to significantly increase capacity and save resources in the long term. 

Initial scenario 

Electric trams are supplied with electrical energy from the substations. When the tram brakes, electrical energy is produced via the electric motor in generator mode and fed back into the grid. This energy can only be used if another consumer is in the immediate vicinity and can absorb a large proportion of the energy. 

The ideal situation would therefore be another vehicle that starts at the same time and can thus be driven by the recuperated energy of the braking vehicle. This timing is difficult, requires enormous synchronisation effort and has an impact on the timetable and electrical grid stability. Therefore, in practice, this braking energy is often dissipated by braking resistors located on the vehicle and converted into heat. 

This energy converted into waste heat is lost and can no longer be reutilised. RET was therefore looking for a solution that would utilise the energy fed into the tram network from the substations as efficiently as possible. 

Optimal utilisation of braking energy 

The idea: a “power bank” that stores this energy and makes it available for the next tram. It acts like a transformer station without a power connection. A transformer station that uses batteries and modern high-performance electronics to store electricity and make it available again at the right time. 

RET had the concept calculated and simulated by the Austrian company Kruch Railway Innovations. A recently constructed turning loop in Rotterdam with high vehicle frequency is an ideal place to test this power bank. The modelling carried out by Kruch using energy flow simulation (EFS) shows that a power bank would be a solution here. This allows RET to significantly increase capacity without having to build a new substation. 

Would you like to know more about the EFS energy flow simulation? You can find all the information and further reference examples here.