Peterbilt displayed a Euro-style high cabover truck, a demonstrator model powered by a prototype hydrogen-fueled internal combustion engine, at the recent American Trucking Associations annual management conference in Austin, Texas.

There it was on the convention floor, parked between a red Peterbilt Model 579 UltraLoft with Epiq Max aero package and a white-and-blue Model 579EV, a DAF XF from Paccar’s European subsidiary, DAF Trucks.

The DAF XF was equipped with a modified version of the Paccar MX-13 engine, producing 295 hp and 1,250 lb.-ft.

A hydrogen-powered engine requires spark ignition, which means it’s not entirely zero emissions — there is a small amount of NOx produced.

There are some questions as to whether that NOx will preclude hydrogen combustion engines from being classified as zero emissions. White said the U.S. Environmental Protection Agency currently recognizes it as zero emissions, but the California Air Resources Board is another story.

Modifications had to be made to the pistons and heads, as well as the fuel system, explained Jacob White, director of product marketing. There’s a different compression ratio, with a lower amount of pressure than that of a diesel.

The four 90-liter hydrogen tanks look similar to CNG tanks, but the hydrogen is under slightly higher pressure.

Pros and Cons of Hydrogen Combustion Engines

Using hydrogen to power a combustion engine rather than using it for a fuel-cell-electric truck would have several advantages, White said:

• Lower acquisition cost because the truck is less complicated than an FCEV.

• The fuel cost would likely be lower, because an internal combustion engine can run on a less-pure version of hydrogen than a fuel-cell-electric powertrain that has to run the H2 through an electrolyzer to turn it into energy.

• Extending range is a matter of adding fuel tanks

• The operation is similar to compressed natural gas trucks, which is more familiar to fleets.

Asked about drawbacks, White said, the energy density of hydrogen is lower than that of diesel. That means it needs more fuel to go the same distance as a diesel-powered truck.

The most obvious negative, of course, is a lack of hydrogen fueling infrastructure. Right now, Europe is ahead of the U.S. in developing the hydrogen infrastructure for H2 ICE or FCEV trucks, WhIte said.

“It will take time and investment,” he said.

Demonstrating What's Possible

It was the first U.S. outing for the truck, which nearly two years ago received the 2022 Truck Innovation Award from the International Truck of the Year program.

“The real purpose of this is to show it’s possible,” White said. “There’s a lot of conversation around EVs, FCEVs, but we need longer range.”

There’s still a lot of work to do before a production version, he added, but “it’s definitely on the product road map.”