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AC Transit Unveils New Fuel Cell Hybrid Bus

AC Transit / UTC Power / ISE / Van Hool hybrid fuel cell bus.

AC Transit of Oakland, California has unveiled its new hybrid-electric, hydrogen fuel cell bus at the APTA expo last week.

The AC Transit design, three years in the making, features a UTC Power 120-kW fuel cell power system and an ISE Corporation hybrid-electric drive system installed in a Van Hool (Belgium) bus.

AC Transit, ISE and Van Hool are already working together on a gasoline hybrid-electric fleet of 30-foot neighborhood buses.

The bus is one of four such buses being built for the North American market and is due to enter regular service this fall. As the lead transit agency in this partnership, AC Transit will acquire three of the four buses, with SunLine Transit of Thousand Palms, California acquiring the fourth.

Configuration of the hydrogen hybrid buses under construction for AC Transit and SunLine.

The 120-kW UTC Power system combines oxygen from the air with hydrogen gas stored onboard the bus, at low, near-ambient pressure, removing the need for a compressor and increasing the fuel efficiency and reliability of the whole system.

It also makes the bus very quiet.

The PureMotion 120-kW fuel cell power system represents the culmination of two years of research and development substantially funded by the U.S. Department of Defense through the U.S. Army Tank-automotive and Armaments Command (TACOM) and the U.S. Department of Transportation through the North American Vehicle Consortium.

Sodium Nickel Chloride high-temperature (“Zebra”) batteries can store as much as 53 kWhr of electrical energy and release up to 95 kW of power, enabling efficiency improvements through regenerative braking, while augmenting the 120 kW of power available from the fuel cell. The bus uses dual Siemens traction motors.

We’ve taken this bus up to 70 miles per hour on the freeway, and in our testing phase, we have achieved twice the energy efficiency of diesel.

—Dave Mazaika, President and CEO of ISE

Comparing Emissions and Fuel Consumption
Fuel Cons.
mpgde = miles per gallon diesel equivalent
Source: ISE Corporation
Conventional Diesel 30 0.24 2,200 4 mpg
Conventional CNG 15 0.02 2,500 3.3 mpgde
Hybrid Diesel 13–16 0–0.03 1,700 5–6.5 mpg
Hybrid CNG 2 (?) 0.01 (?) 2,000 3.9 mpgde
Hybrid Gasoline 0.5 0 2,100 3.4–6 mpgde
Hybrid Hydrogen ICE 0.5(?) 0 nil 5 mpgde (?)
Hybrid Drive Fuel Cell 0 0 0 7–10 mpgde

AC Transit engineers worked closely with UTC Power, ISE, and with bus and coach manufacturer Van Hool to design a glider that would accommodate this integrated hybrid system. All parties successfully achieved the fuel cell integration without compromising the features of true low floor transit bus: three wide entrance/egress doors, completely low passenger floor from front to very back of the bus, expansive windows and high ceilings, electric air-conditioning, as well as other features typical to a Bus Rapid Transit operation.

Utilizing the same vehicle design developed by Van Hool, UTC, and ISE for AC Transit, a demonstration bus will be built for the European market to conduct additional testing and evaluation of vehicle performance and to further advance the use of fuel cell hybrid-electric technology.




I guess those are the hydrogen storage tanks on the roof. They must be enormous, to hold enough uncompressed hydrogen for daily use. I wonder how far it goes on a fillup?


A zinc-hybid recently traveled 127 miles in simulated urban service. I'd also like to know the range. The mileage figure of 7-10 equivalent would be close to 5 miles per pound of hydrogen.


The zero CO2 emissions listed in the table must assume non-fossile-fuel hydrogen production, I assume. Is this the actual plan?


That’s just operational data—as is the CO2 data for all the other fuel/drive combinations.

That said, AC Transit’s long term vision is of renewable, solar or wind power-generated hydrogen. Currently, the company operates an electrolysis station in Richmond and is also bringing a small steam methane reforming facility online.


By abmient pressure system they mean the hydrogen is delivered to the fuel cell at normal pressure not that it is stored at such pressures.
Some older fuel cell designs actauly needed a booster to push the hydrogen as it needed to enter always at 2500 psi and thus when you got below that you had to presurize it.


Mike, do you have any updates on this? Any idea which routes (i.e. bus route numbers) this bus is driving on? I'm going to soon move to the area and would love to "test-drive" this bus.


Also from the table on here, one can see that the emissions, as well as fuel consumption, of a hybrid disel bus are lower than those of natural gas buses.
Can someone explain to me why natural gas buses are being promoted as "clean air" buses then? Why aren't we pouring more money into hybrid diesel buses? I also imagine that infrastructure costs would be much lower for such a hybrid bus.


So far, AC Transit has been running its fuel cell buses on the 7, 9, 65, and 67 lines. You might give them a call when you get in the area to see where you might be able to hop a ride. :-)

Bill Bishop

Go to for as free sample of an aero coating that complements this technology by reducing turbulence at the back and sides of almost any vehicle....40 ft coach school buses have recorded mileage increases from 7 mpg to 9.5 mpg! Bill

Shawn Black

Back in November you had an article about a website offering a free sample of an aerodynamic coating
( for vehicles. Since these people were willing to put theier money where their mouth is, I got my free sample. Took 6 weeks to get it but I tried it on my 2005 Magnum Hemi V-8 and it worked as advertised. My highway mileage jumped instantly from 21 mpg to 28+ based both on onboard computer readout as well as claculations based on mpg at the pumps... Shawn

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