Reducing Ground Support Emissions

New electric or electric conversions of GSE have helped minimize the ground support fleet’s contribution to carbon emissions at airports throughout the world. Hydrogen-fueled internal combustion engines offer one other less publicized way...


New electric or electric conversions of GSE have helped minimize the ground support fleet’s contribution to carbon emissions at airports throughout the world. Hydrogen-fueled internal combustion engines offer one other less publicized way.

Technology for GSE developed by Canada’s Can-Am Modev, for example, had its beginnings in 2002, but wasn’t seriously considered until 2003. And it didn’t reach the in-service test stage until 2010, and those tests continue today at Montréal-Pierre Elliott Trudeau International Airport (YUL) on a fleet of hydrogen-powered tractors.

The company first paired its engine technology with another power source – fuel cells – before settling its energy on a hydrogen-fueled internal combustion engine. By 2004, the Canadian government considered for the first time to fund a study of three types of hydrogen-powered ground vehicles for the so-called “H2Port” project:

  • Baggage tractors
  • Transit buses
  • Taxi cabs

For a few years, the project spent more time derailed than on track, before contracts for a number of baggage tractors were finally issued in 2009. The other two vehicles failed to make the cut.

The reputation for dependability and safety in aviation-related equipment comes from data-driven designs. No airline or ground operation would consider equipment unless it had been proven in testing or by use in a similar application elsewhere. Recognizing this, the Canadian government funded the test case at YUL. Air Canada continues to run the test.

The plan was for these tractors to gather usage data for fuel consumption, fueling cycle, maintenance, utility, ease of use, and other items. This data may give airlines and baggage handling operations a clearer picture of this alternative technology.

Currently, three baggage tractors have been converted to use hydrogen at YUL. Operating data continues to be collected and the results will eventually be shared with airlines and baggage handling companies. Approval from the Canadian Ministry of Transport is the next step.

One unexpected benefit, however, is already apparent. Internal combustion engine-powered tractors are not permitted inside the airport terminal building due to emissions.

Currently, such tractors are unhooked and electric-powered tractors are connected to complete the transfer of baggage from the ramp to the baggage conveyor. The time required to move baggage between aircraft and conveyor is obviously increased.

Since hydrogen-fueled tractors emit only water vapor, they can proceed directly to the conveyor from the ramp. It is estimated each test tractor saves 1.3 hours per day in unnecessary hooking/unhooking.

 

THE CONVERSION PROCESS

Since hydrogen is less dense than other fuels, storing it takes up more room and special provisions had to be made for on-vehicle storage. Can-Am Modev selected two Dynetek high-pressure vessels, locating them behind the seats and in front of the hitch pin. Fuel piping and delivery to the engine had to be designed for the new fuel, but the company adapted fuel injection control schemes used for gasoline engines. There were other differences, such as injectors and sensors.

Other than the new fuel system for the tractor, the company says the conversion is very similar to an engine replacement for a worn-out engine. The engine bolts directly to most tractor transmissions with no adaptations, since, in most cases, the block is the same as what came from the tractor manufacturer. The “gas” pedal is electronic rather than mechanical, just as in many cars today. The engine controller mounts to the firewall or inside fender, depending on the tractor manufacturer.

The company says finding a zero-NOx operating point and staying there under variable loads and speeds took a fair amount of work. The engines themselves were higher compression than for unleaded gasoline, but nothing that required new science.

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