Currently under trial in Germany, regenerative brakes could reduce locomotive emissions while increasing efficiency.
Slowing down and stopping motorized vehicles requires the conversion of kinetic energy, movement, into another form of energy. The energy is usually converted to heat resulting from friction, i.e. from the brake pads on your car. Essentially, the energy is wasted.
MTU, a division of the engine, propulsion, and power systems company Tognum Group, has recently developed a braking system capable of harnessing and reusing the energy expended by trains when braking. This would allow the excess kinetic energy, which is usually wasted, to be converted and stored by the train for future use in starting or slowing the train’s motion.
The new regenerative braking system aims to reduce consumption from the train’s ‘external’ energy sources, such as their current electric and diesel engines. The system is currently being used on a trial basis for a train running between Aschaffenburg and Miltenberg, Germany. The train in question, a Siemens Desiro Classic VT 642 locomotive, is now the first hybrid train in the world.
Since MTU installed their braking system, which consists of a pair of 315 kilowatt hybrid power packs and batteries, to work in conjunction with the existing 275 kilowatt diesel engines, the train has seen a 25% decrease in fuel consumption and carbon emissions.
Currently, approximately half the trains in Europe are electric powered. This new proposed hybrid system would not only make for a smooth transition for the other 50% of locomotive transport, it could also help make existing electric trains more efficient by reducing their consumption.
The German State Secretary, Rainer Bomba, has already called for ‘new mobility and vehicle concepts for an environmental friendly future.’ A key component of this project is that the German Federal Ministry of Transport is helping to fund ‘a whole host of projects nationwide for the transport of people and goods.’
Potentially, all the trains in Europe could be hybrids. However, there are still a few hurdles to overcome.
Namely, while the system is more efficient, it is, like most new technology, a greater investment to develop. Additionally, it is unclear whether Tognum’s system is reliable enough to withstand the wear-and-tear experienced by rail systems from their frequent start-and-stop motion. This has resulted in the trial currently being limited to trains with high energy losses, but could be expanded to encompass more trains if found successful.