British bus manufacturer Alexander Dennis is expanding its product line, adding a double-decker model powered by a fuel cell drive. This new model is also equipped with ZF's AxTrax AVE electric drive axle to prevent local emissions. ZF also provided additional hardware and software for optimum performance.

An initial prototype was said to be "impressive, operating at high efficiency during field testing".

The bus, designed by ADL, is based on its Enviro400 model line. This configuration comprises a secure system that uses hydrogen to generate electricity, which, in turn, drives two electric wheel-hub motors in the electric portal axle. As fuel cells do not use fossil fuels, they produce no hazardous emissions, only steam.

ADL spent two years developing this hydrogen-driven double-decker bus with ZF selected as a partner right from the start. During field testing, the prototype operated along real bus routes in several cities throughout the United Kingdom.

In addition to the AxTrax AVE, ZF also provided the inverter, the EST 54 electronic control unit and the appropriate control software. In this complete system, the supplier optimally aligned performance, efficiency and the service life of the drive. Providing a complete system helped reduce the test and homologation costs for ADL.

The British manufacturer has already presented the prototype of the new fuel cell double-decker to the public as well as several fleet operators.

The AxTrax AVE was introduced in 2012 and has since been sold worldwide. The electric drive axle can be used in a wide array of possible applications as it can also be used with hybrid powertrains or purely electrically with lithium-ion batteries.

In addition to drive performance – 250 kW up to a maximum axle load of 13,000kg – the compact design also appeals to vehicle makers. Since neither a conventional unit nor a universally jointed shaft is necessary for transmitting power, manufacturers now have more freedom to design the passenger area the way they want. They can add seating and standing room, for example, or provide for step-less entry and exit or a completely flat passageway.