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University of Delaware Introduces Series-Hybrid Hydrogen Fuel Cell Bus

The University of Delaware hydrogen fuel cell hybrid bus.

Researchers at the University of Delaware (UD) unveiled a series-hybrid hydrogen fuel cell bus developed in partnership with a consortium that includes EBus, Ballard Power Systems, Electric Power Research Institute (EPRI), Air Liquide Advanced Technologies US, and the Delaware Transit Corp.

EBus adapted its existing 22-foot, 22-passenger chassis and electric drive system to use a Ballard 19 kW Mark9 SSL fuel cell stack as a range extender for a 60 kWh Ni-Cd battery pack. The bus has twin 5,000 psi tanks on its roof that can store 16 kg of hydrogen and has an estimated range of 200 miles.

EPRI provided expertise and software to model and simulate various sub-systems of the vehicle. Air Liquide provided their climate-controlled, high-bay facility to house the bus, and installed a hydrogen station next to the high-bay for refueling the bus.

To the best of our knowledge, this is the first fuel cell powered bus that has such a small stack. If we can demonstrate that it can handle the urban transit drive cycle, it will take us one step closer to commercialization.

—Suresh Advani, George W. Laird Professor of Mechanical Engineering, UD

The fuel cell activates when the battery State of Charge drops below 60%, according to Professor Ajay Prasad. The University of Delaware team will acquire data continuously from all the sensors integrated into the bus during transit operation on campus, including pressure, temperature, humidity, gas and coolant flow rate. The researchers have the flexibility to modify the control algorithm based on the data and to optimize the settings for maximizing performance and stack life. 

Initially, the bus will operate on the University campus. Subsequently, UD will collaborate with Delaware Transit Corp. to perform demonstrations to the general public outside of the University.

Plans are already in place for a second, larger, bus, employing the same consortium of companies, including EBus, according to Professor Prasad.

The hydrogen fuel cell bus project is supported by a $1.7 million grant from the US Department of Transportation’s Federal Transit Administration, matched by private financing from companies working in partnership with the University.



As a range extender running in a constant state the fuel cell PEM will last considerably longer than those in fuel cells in a regular fuel cell vehicle.
I'd love to know what the thinking was behind a Ni-Cad battery. You would think the memory effect would kill it.


I would guess that Chevron Ovionics would not let them use
NiMh !


EBus has been using NiCd's for years, and that's what they like. The memory effect is not really an issue on this bus since we overcharge the batteries by about 25% using a plug-in slow charger.

Interestingly enough, the fuel cell does not run in constant state (yet). Currently, it receives a power request from the vehicle computer that is based on the current SOC and average power usage (traction system, accessories, etc...). Because the SOC changes quite frequently, the power request also changes. So the fuel cell can actually see some significant transient loads. However, it is still much better than a direct drive fuel cell (no batteries).


I like the idea of using nihm batts also, but it seems the memory effect of nicads only happens when you leave them fully charged or at a constant low state. Sounds like this system lets the batteries run through a large range of discharge.


I like this configuration. Series hybrid, smaller chassis and smaller fuel cell stack add up to something that you might be able to cost effectively produce in larger numbers. I believe that local bus transit would be more widely used if you had many more smaller buses to cut down on wait and transfer times.


SJC: I think that it could be a matter of economies of scale, e.g., personnel costs rise with more drivers. I do like the thinking since one size does not fit all.

Would it be more cost effective to use a trailing bus, perhaps more often than is done now for times of peak passenger usage, yet use a smaller bus most of the time when usage is less?


I have no idea, I assume that the urban planners would know, but that might be a misguided assumption. All I know is I would not like riding the bus, because it takes a lot longer to get somewhere. If it is a high use route, you double up on the smaller buses. I would not mind waiting 5 minutes for the next bus, rather than be crammed into a larger one that comes through less often.

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