Hydrogen ‘Inevitable’ for Commercial Vehicles

With battery charging infrastructure still spotty and corporate carbon-reduction targets looming, the commercial-vehicle sector increases interest in low-carbon fuels.

Example layout of hydrogen storage tanks in a Class 8 tractor. (Faurecia)

With the perception of diesel engines as bad actors in the worldwide transportation-emissions crackdown, the commercial-vehicle sector is racing to identify and develop propulsion technologies that will simultaneously reduce its emissions “profile” and help OEMs and engine makers achieve new and ambitious carbon-reduction targets. Most industry players would like battery-electric propulsion to be the ultimate solution, but for now, many commercial-vehicle duty cycles and an unforming recharging infrastructure mean battery-electric propulsion for many types of medium- and heavy-duty vehicles isn’t a workable solution.

Cummins B6.7 engine is designed to be “fuel-agnostic,” which includes accommodating hydrogen. (Cummins)

New low-carbon fuels – and particularly hydrogen – are the answer until batteries and the charging infrastructure get better, concluded most panelists speaking in the “Heavy & Medium-Duty Technologies” panel session at SAE International’s 2024 Government/Industry Meeting in Washington, DC in January 2024. But even “clean” liquid fuels and hydrogen face steep adoption curves, a chief reason being their own nascent supply and refueling networks.

John Pendray, Cummins senior technical advisor – technology development. (SAE/Bill Visnic)

The industry’s OEMs and suppliers need propulsion technology that can “allow customers to succeed regardless of infrastructure status,” said John Pendray, Cummins senior technical advisor for technology development. He said the CV sector doesn’t want to wait a decade for battery EV maturity – “any fuel that anyone can bring to the table that’s low-carbon” is an actionable option, he claimed.

Low-carbon fuels and hydrogen, many panel speakers said, enable the use of existing internal-combustion engines that are capable of satisfying medium- and heavy-duty truck duty cycles – and ideally can be “drop-in” substitutes for diesel and gasoline, meaning the new fuels could use the existing universal refueling infrastructure. Hydrogen, meanwhile, can fuel either modified IC engines or fuel-cell electric trucks.

“Hydrogen is inevitable,” asserted Mohammad Fatouraie, director of system engineering in the Bosch Powertrain Solutions division. “Hydrogen is going to happen. But for it to become competitive is going to take a while.” A current problem for hydrogen, he said, is “having it available at a place that it’s needed for fleets.”

Holistic approach to hydrogen

Mohammad Fatouraie, director of system engineering, Bosch Powertrain Solutions division. (SAE/Bill Visnic)

“We need to think a little differently about the paradigm we design from,” Fatouraie added. He said that Bosch has developed a vehicle energy-management case study based on a fully

loaded medium-duty pickup truck. The goal is the same range and performance for a zero-emissions variant when compared to one with a conventional ICE powertrain.

The exercise, he said, is to force a process that embraces a holistic engineering approach rather than focusing on optimizing individual systems. The study intersects powertrain, thermal management and “powernet” – a link to ADAS (advanced driver-assistance systems) and infotainment systems – and at their intersection derives Vehicle Energy Management, or VEM.

Fatouraie said the approach led to better understanding of the real tasks involved in achieving a no-compromise zero-emission vehicle. For a FCEV variant, for example, he said that heat dissipation at high loads “is a key enabler.”

Agarshna Murari Muthukannapiran, manager at FEV Consulting, said his company also has developed a powertrain modeling tool that helps customers to quickly identify a “best-fit” powertrain based on a variety of criteria. The powertrain selection tool uses inputs for duty cycle, payload and other variables – including a target total cost of ownership – to suggest the best powertrain based on operation in six regions and seven powertrain options.

The FEV tool determined that for a battery-electric approach, some 80% of Class 4 to Class 8 CVs require around 2 kWh per mile from a battery pack and that pack sizes would range from 60 kWh capacity up to 1 MWh. To reach parity with conventional powertrains, he said, an IC engine fueled by compressed natural gas (CNG) or CNG hybrid offers the “quickest” approach.

Muthukannapiran said BEVs currently can make a strong business case in some applications, particularly if hydrogen fueling infrastructure lags. He said that the company’s modeling determined that BEVs are a better total-cost solution if the price of hydrogen is $10 per kilogram or more. He added that BEVs aren’t likely to be an effective option for high-load vehicles such as cement mixers.

ICE remains in play

Auxiliary heaters can more-efficiently provide cabin heat for electrified transit buses, for example, preserving valuable energy from the vehicle’s onboard battery pack. (Dometic)

For commercial vehicles of almost all types and classes, internal combustion is going to continue in a long transitional phase, most speakers at the SAE conference asserted. And just as in the passenger-vehicle sector, hydridization is a central part of the discussion.

“One of the delightful things about hybrids is that the ICE can do what it does best,” said Cummins’ Pendray. He said that IC engines still “will be around in the 2050 timeframe,” but they are not going to have the role they have today.

Bosch’s Fatouraie said blending IC and BEV attributes in a range-extender layout–, such as the one Stellantis is preparing to deploy for the light-duty Ram pickup – may be a good solution as the propulsion transition evolves. Range-extender setups can take the pressure off “the immutable need for charging infrastructure,” he said.

In another strategy to ease the transition from ICE to EV, David Mountford, product manager for Dometic, briefly detailed his company’s work on a modulating, variable-cycle/output auxiliary heater for EVs and other electrified vehicles. A common application, he said, is for electrified transit buses, where the auxiliary heater is a more-efficient solution for providing cabin heat than using valuable energy from the vehicle’s onboard battery pack.

[Mountford said drawing electric cabin-conditioning heat from the vehicle batteries has an outsized detrimental effect on driving range. Every kilowatt of heat output, he explained, equates to a driving-range reduction of approximately 1 km (0.6 miles).

“Let’s get the net gains now,” Mountford said, of options such as using low-carbon fuels and other “blended” propulsion strategies rather than focusing solely on EVs. He said encouraging a variety of technologies that can produce meaningful carbon reductions now is preferable to “waiting for perfect.”