Risky Behavior

HYDROGEN PM

Matthew Riley, fleet support engineer for fuel cell maker UTC Power, a division of United Technologies, visits SunLine regularly to help train technicians and monitor the performance of the VanHool fuel cell "SunBus." On a recent stop at the SunLine maintenance department, Riley explained the basics of fuel cell PM:

"The PM tasks themselves are not particularly novel compared to a regular bus," he explains. "They include things such as changing air filters, checking and changing filters in the water system. Other things would include fluid change-out and flushes of the water system as well as the water ethylene glycol (WEG) coolant system. So the filters themselves might be a little bit different-shaped, and some of the fluids might be different, but the type of preventive maintenance that's required is very similar to other buses or automotive products.

"In this case, some of the PM tasks I've been doing are a little bit ahead of schedule, because we're going through the various steps for the first time with this bus, and also this bus is operated in the Coachella Valley, which, because of the high amount of dust and sand, is a more of a severe operating environment… so we're keeping an early eye on things. As far as checking a filter or a similar task, it's a fairly quick task. You spend more of your time removing a panel or a grate to get to the filter.

"With a fuel cell, particularly with the fuel cells designed and operated by UTC, it has a more significant water system, and the water system helps manage the temperature of the fuel cell and water produced by the fuel cell reaction between hydrogen and oxygen. So you've got a lot of areas within the fuel cell where you've got water going through there.

"The fuel cell produces DC electricity that goes through to the power management system on the bus, and the power is then diverted to either the traction motors to move the bus or can be diverted to the batteries for storage, as well as running other auxiliary equipment, such as the heating or air conditioning system.

"This is a hybrid drive system in that it combines a primary power source with a secondary storage system for power and an electric drive system, rather than a standard transmission. The fuel cell operates at just a little above ambient pressure, which helps keep the fuel cell operation very quiet.

"Because of transit agencies' close relationships with the public, most are probably quite interested in exploring new technologies. Particularly at SunLine and AC Transit (a fleet in Oakland, CA, running three other UTC fuel cell buses), you've got a lot of people from maintenance supervisors, engineers, to managers, who are very interested in both exploring new technologies and exploring environmentally-sound policies.

"With all of the PM tasks, such as changing filters, we try to make sure that those parts are reasonably accessible, i.e. near the outside of the system, so they can be changed out easily. In some cases we might use a quick connect fitting, rather than a threaded fitting, to help make removal and reinstallation a little bit quicker.

"My role is technical support, training, and troubleshooting. I also spend a lot of time taking the data we produce operating the fuel cell in the real world, and I go through that and try to make improvements to the existing system as well as looking for the possibilities of improvements in future generations of product."