BP and GE Together to Develop Hydrogen Power Plants and Technologies
Peabody and Rentech Partner to Develop Major Coal-to-Liquids Projects in the US

Azure Dynamics to Produce Series Hybrid Shuttle Buses with StarTrans

The new hybrid shuttles will use the HD Senator bus body, shown here in a conventional application.

Azure Dynamics Corporation has signed a Memorandum of Understanding (MOU) for the production of hybrid shuttle buses with StarTrans, a business division of Supreme Corporation and one of North America’s leading commercial bus manufacturers.

Under the proposed terms of the MOU, Azure will provide StarTrans with a hybrid cab-chassis—a derivative of Azure’s series-hybrid chassis (earlier post) integrated with a newly developed cab—on which StarTrans will assemble their shuttle bus body.

StarTrans intends to utilize its HD Senator Series model line of shuttle buses.

The current series-hybrid chassis—as applied in Azure’s Citibus shuttle bus line— uses a 4.8-liter gasoline-fueled GM Vortec engine as the genset combined with a 110 kW induction motor and a NiMH battery pack. The shuttle has a top speed of 65 mph, and an all-electric range of 1.5 miles.

NOx 0.01
PM 0.0
HC 0.12
CO 0.61

Azure’s systems have demonstrated nearly a 50% reduction in fuel consumption on a mile per gallon basis in city driving, compared to conventional chassis. Azure’s hybrid chassis also significantly reduces vehicular emissions, achieving reductions in hydrocarbon, carbon monoxide and nitrogen oxide emissions of up to 83%, 91% and 53% respectively.

Azure and StarTrans plan to jointly market the hybrid shuttle bus via the StarTrans dealer and distributor network.


allen Z

Is this any better than the GM hybrid bus already in service? Perhaps its small size may come in handy, but the fact of having competing designs based on vehicles of the same company smells like a new take on Pontiac vs GMC vs Saturn.


There is the reason why they employ gasoline engine and not diesel: diesel engines, even in hybrid buses, have troubles to meet extremely high emission requirements for city buses in US. CNG buses with SI stoichiometric engines are meeting these requirements, but suffer from low range per refueling.

There is one very interesting possibility, thought. Most of diesel engine manufacturers currently have engine models converted to run on CNG in high-compression lean SI mode. Thermal efficiency is comparable to diesel engine, engine wear is half of regular diesel, and oil change intervals are doubled. The trick is to support very tight fuel/air ratio below detonation limit, but above lower combustion limit. Emissions are very low due to very lean combustion, with lambda more then 2. Gasoline fuel can not be used in these engines, because even small rich spot in combustion chamber around not completely evaporated/imperfectly mixed gasoline droplet will serve as source of detonation. NG is critical for such engines. The problem is that it is very hard to control proper operation at sharp changes of power output.

Dropping such engine in series hybrid solves all problems. Engine is always working at stable (or slowly changing) output, and range is greatly increased due to diesel-like engine efficiency and because of hybrid driivetrain.


Do these thing really need a 4.8 L engine to get 110kW. If it is a series hybrid they could do it with half that and add turbo charging for improve efficiency, operating in a fairly narrow rpm load band and shallow cycling the battery to act as the transmission.

That would be starting to get close to what we need. Add in the hi comp si NG factor as an alternative where infrastructure is practical and you have a pair of really nice products.



John Ard

Why wouldn't a system like this work in a passenger car or pickup truck? It could be an EV with an onboard generator for if an outlet isn't handy.


Pure series hybrids tend to be more expensive and suffer from lower fuel economy in steady state driving, like on the freeway, so they tend to go with series-parallel such as the Toyotas or just parallel like the Hondas to make them more affordable and able to meet the expectations of commuters.

The comments to this entry are closed.