Hydrogen Fuel Cell Bus Technology State of the ... - NEXTHYLIGHTS

Hydrogen Fuel Cell Bus Technology State of the Art Review
4. There is no mechanism to capture the kinetic energy dissipated when the bus
operator applies the brakes.
In the light of these problems, all of the main fuel cell bus developers have now moved
to a fully hybridised mode, with the fuel cell operating in a series hybrid configuration 6 . In
a hybrid mode, all of the above problems can be overcome, as the energy store buffers
peak loads and allows regenerative braking (Figure 4, below). In these „next generation‟
fuel cell buses, developers are still experimenting with the energy storage device, which
can be batteries, ultra capacitors, or a combination of both 7 .
Figure 4 Layout of the hybrid drivetrain configuration for hybrid fuel cell buses. The
drivetrain can include either a battery system or ultra-capacitors or a combination of
both.
6 One of the earlier public demonstrations of hybridised FC buses was performed by Toyota and
Hino under the Japan Hydrogen and Fuel Cell program (JHFC) in 2002. Hybridised designs,
however, became the dominant choice only from 2005. The largest fleet demonstration ever
programmed started in occasion of the 2010 Winter Olympic Games in British Columbia,
Canada, performing 20 hybridised buses. Today, every demonstration of fuel cell buses is based
on hybridised architectures.
7 For example, the new Evobus Citaro hybrid uses batteries only, the new Wrightbus hydrogen
bus for London will only use ultra-capacitors and the APTS bus for Amsterdam and Cologne will
use a combination of both.
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