Once considered a niche environmental play as the automotive industry focused on battery-electric and fuel cell vehicles, hydrogen internal combustion engines have gained renewed attention as a green vehicle technology.
A pending European Union regulatory change would classify heavy-duty trucks using the engines — which burn hydrogen to push pistons — as zero-emission vehicles. That could spark an echo in pickups and smaller vehicles in other markets.
“It was a light-switch moment,” said Jim Nebergall, general manager of Cummins Inc.’s hydrogen engine business.
EU regulators have proposed changing their zero-emission definition to ensure that buses and heavy-duty trucks equipped with hydrogen internal combustion engines qualify. They said such vehicles should be included because hydrogen is a fuel with no carbon content. The proposal is passing through the legislative procedure in the European Parliament and Council of the European Union. The vehicles would produce a low level of nitrogen oxides emissions, but the regulators’ focus is on carbon emissions.
“If anything, it poses a compelling example of what could be done and how it could be regulated,” Johan Lunden, senior vice president at Volvo Group’s Project and Product Strategy Office, told Automotive News.
The pending EU change creates a business case for using hydrogen combustion engines in large vehicles across much of Europe. That would help build the volume manufacturers need to make the investment in the engines and vehicles worthwhile, according to the companies.
Stephan Olsen, Kenworth’s general sales manager, also said the move gives the technology a push. DAF, the brand’s European sibling, is already testing a prototype 13-liter engine.
“Hydrogen combustion presents a fuel source and energy source that is understood in a piston engine that we all know how to operate and service as an industry,” Olsen said.
Paccar, which owns the Kenworth and Peterbilt brands, believes it could get a hydrogen-burning truck “extremely close” to zero tailpipe emissions.
Volvo has a similar assessment.
“The hydrogen internal combustion engine will be an attractive and competitive choice because it doesn’t require complex, expensive batteries or a complex fuel cell stack,” Lunden said.
It will need fuel tanks, which are pressurized, making them more complicated than gasoline or diesel counterparts. Still, those are already under development for fuel cell vehicles and could be shared, according to Volvo and Cummins.
Nonetheless, much of what’s needed for hydrogen combustion is less costly than other forms of green transportation because piston engine technology is so well developed and understood, said Nathan Niese, a partner and global topic leader for electric vehicles at Boston Consulting Group.
Cummins, which supplies diesel engines across the automotive spectrum, wants a 15-liter hydrogen combustion engine in production in 2027. It also is working with Indian automaker Tata Motors on a 6.7-liter hydrogen combustion engine that would produce up to 290 hp. That’s the type of engine that would work in pickups.
Daimler Truck also is considering the technology.
“When we talk to regulators, we see and hear that they more and more understand the chances related to this because the emissions are really negligible, and there could be significant benefits for our customer,” said Andreas Gorbach, Daimler’s head of truck technology.
Although much of the industry considers hydrogen internal combustion technology viable, some hurdles remain.
There’s a debate about whether liquid or gaseous hydrogen is the best way. Toyota Motor Corp., also developing the technology, said liquid hydrogen holds greater energy density and provides a longer range. But both the storage and fuel pump technology must function at minus 253 degrees Celsius.
Gaseous hydrogen requires pressurization and more extensive fueling infrastructure but doesn’t have the same temperature constraints.
Hyundai, another automaker developing hydrogen-fueled vehicles, believes the challenges can be overcome.
“There’s technology needed on the injectors to burn at a higher rate and technology needed on the combustion chambers because the displacement is higher for the same amount of horsepower,” said Ken Ramirez, head of the global commercial vehicle business division for Hyundai Motor Co. “But this is going to come.”
There are more problems to solve before hydrogen-burning trucks and other vehicles are on U.S. roads or elsewhere.
At the top of the list — there’s almost nowhere to fuel them. A Department of Energy tally shows 57 hydrogen stations in the U.S. — all in California. That compares with more than 50,000 public BEV charging stations, according to the government. There are more than 145,000 gasoline stations across the country, according to the American Petroleum Institute.
And while hydrogen looks to be a green fuel in future years, it is mainly produced through a process that requires burning fossil fuels, negating any carbon savings.
Not all regulators will follow the EU’s lead.
The California Air Resources Board intends to block internal combustion engines in almost every use.
“For passenger vehicles and cargo trucks, there is a zero-emission option [in fuel cell and battery-electric vehicles], and that transformation has begun,” Hector De La Torre, a board member, told Automotive News. “Why would we allow for pollutants in addition to greenhouse gases when we don’t have to have them?”
CARB Executive Officer Steve Cliff urged the EPA at a May 23 hearing to “not promote competing technologies like hydrogen internal combustion engines” out of concern for nitrogen oxides emissions.
According to the board, at least seven states plan to follow California’s lead for heavy-truck emissions.
Another problem is hydrogen’s expense.
The cost of hydrogen in California, where it is sold for passenger vehicles, ranges from $12 to $16 per kilogram, according to S&P Global Mobility. In other regions, the price can be higher.
That’s why Toyota is providing buyers of its Mirai fuel cell car complimentary fuel for six years or a credit for $15,000 in fuel, whichever comes first.
Jamie Fox, an analyst at Interact Analysis, said prices of $10 per kilogram should be achievable soon if trucking industry economies of scale are achieved. Interact Analysis forecasts $5 per kilogram in 2030.
The Energy Department wants to jump-start hydrogen production by spending $7 billion from the Bipartisan Infrastructure Law to create six to 10 clean hydrogen regional hubs. The department said it hopes the hubs can help lower the cost of green hydrogen to $1 per kilogram a decade from now.
Fox analyzed the total cost of ownership for long-haul trucks with different powertrains purchased new this year, driven 600,000 miles and resold in 2029.
A battery-electric truck yields the best result — a total cost of $560,000. The conventional diesel rig is next best, at $666,000. The hydrogen options are about double the cost, at $1.2 million for a fuel cell vehicle and $1.4 million for a hydrogen combustion truck. That’s mainly because of the fuel expense.
The battery-electric truck needs just $150,000 in electricity.
The diesel truck requires $400,000 in fuel. Hydrogen will cost $760,000 for the fuel cell tractor and $1.2 million for the combustion version — the difference between the two results from efficiency. A fuel cell operates at 55 percent efficiency, Fox said. But the hydrogen combustion truck yields 35 percent efficiency, requiring much more fuel.
Fox estimates that the cost of hydrogen would have to fall to $3 per kilogram to make the combustion truck viable economically.
Manufacturers expect to see lower hydrogen prices. They believe hydrogen combustion technology will provide an attractive option for situations in which vehicles would benefit from forgoing heavy battery packs or complex technology.
“We see it for regional haul trucks, long-haul trucks and a variety of vocational applications — dump trucks, heavy-haul trucks — anywhere there is a need for a 15-liter engine with almost zero emissions,” said Kenworth’s Olsen.
Although European regulations could give hydrogen combustion technology new tail winds, the transportation industry has toyed with the idea for years.
“This has gone in waves,” said Boston Consulting’s Niese.
“We are in a new wave of curiosity, and if that curiosity translates into real investment and belief, the technology still has some years to play out.”