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

Hydrogen Fuel Cell Bus Technology State of the Art Review
Each of these problems will need to be overcome if fuel cell buses are to occupy the
„environmental bus technology‟ space currently occupied by diesel hybrid buses.
Electric buses have a number of apparently fundamental limitations which will prevent
their widespread adoption. In particular:
The slow recharging time for the buses
The high power demand for charging- which will increase the cost of charging
infrastructure at bus depots
The high weight of the batteries
Limited range – below that required for a typical cycle
These limitations would rule out a fully autonomous battery powered bus, providing, for
example, an 18 hour route. There are however new options being developed which
could include more limited battery capacity (or super capacitors) with fast charging at
bus stops or layover areas (Figure 24, below). These could include inductive charging or
small plug-in stations for short bursts of charge. Such technologies have still to be
extensively tested in commercial applications and hence it is not possible to perform a
comparison with fuel cell buses at present.
Figure 24 Examples of an ultra-fast charging station for ultra-capacitor-powered buses
(left) and a fast charging stations for battery-powered buses (right). Ultra-fast charging
points recharge the buses in few seconds at each bus stop, whilst fast charging points
recharge the buses at the route end only. Sources: http://ceramics.org ;
http://www.proterraonline.com.
Finally, it is possible to remove the batteries all together and move to a trolley bus
architecture. Trolley bus systems offer a highly reliable zero emission solution. However,
the drawback is the high cost of the overhead cabling infrastructure (approx. €400,000 -
€1,000,000 per kilometre including substations) and the fact that the trolley bus will be
fixed to particular routes limiting operational flexibility. The trolley bus architecture is
therefore mainly deployed on short, heavily used inner city routes.
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