- By integrating the battery, fuel cell and super capacitors, engineers have designed a carbon neutral mass transport bus that can be used in both normal and peak conditions.
Clean, quiet and emission free – probably not the adjectives one would expect to use when describing an 18-meter-long bus used for public transportation. But thanks to the innovative thinking from the project’s various partners, this is the only way to describe the new hydrogen-based buses now carrying passengers around Cologne and Amsterdam.
A triple hybrid system
The key innovation coming out of the project is a unique drive system that enables the use of hydrogen fuel cells to drive large vehicles in an environmentally-friendly matter. Leaning on over 60 years of experience in system integration of electrical and hybrid buses, Vossloh Kiep – the project’s lead partner – came up with a design that integrates the vehicle’s three power supplies: the battery, fuel cell and super capacitors. Together, this ‘triple-hybrid’ system provides storage for the vehicle’s power supply, generating an output of 240 kW and a range of 300 kilometres.
Using the triple-hybrid system, the battery-powered bus can self-charge during normal operating conditions. To do this, the fuel cell system, which is located in the rear of the bus, constantly supplies the battery with power whenever the bus is being driven.
But what about peak travel times, when the bus must run longer and, often times, faster? During these periods, the energy provided by the fuel cell is not enough to give the bus the necessary level of power to accelerate. Instead, the energy comes from the super capacitors, which coverts kinetic energy generated when the brakes are used into electricity – thus refilling the accumulators.
Jürgen Langwost, Project Coordinator commented, "The fact that the fuel cells have to operate continuously and do not have to cover different performance needs is one of the main advantages of our system. This is the reason why even relatively small cells can be used, which also have a very long service life."
Coming to a road near you
The result is one of the first fully-electric, 18 metre battery-operated buses that run without producing any greenhouse gas emissions or noise pollution. The system is currently being tested via pilot buses in Cologne and Amsterdam.
In addition to providing clean, quiet transport options, the buses also provide secondary benefits. For instance, industrial plants can use the hydrogen generated by the fuel cells as a waste product. As part of the North Rhine-Westphalian’s Hydrogen HyWay initiative, the bus is an important building block in the quest to turn the region into a leading producer of hydrogen fuel cell technology. The know-how acquired within the project will serve as the foundation for turning the region into a smart mobility hub.
Total investment and EU funding
Total investment for the project “Brennstoffzellen Triple-Hybrid-Antrieb – Emissionsfreie und mit Wasserstoff angetriebene Linienbusse im Alltagstest” is EUR 1 812 281, with the EU’s European Regional Development Fund contributing EUR 779 993 through the ERDF North Rhine-Westphalia Operational Programme for the 2007-2013 programming period.