Which engine technology – diesel, battery-electric, or hydrogen-fuel-cell – will dominate longhaul trucking in 2030? That was the question behind a spirited debate hosted by Mobility Impact Partners, and moderated by North American Council for Freight Efficiency (NACFE) executive director Mike Roeth.

The debate featured: In diesel’s corner, Allen Schaeffer, executive director of the Diesel Technology Forum; representing battery-electric, Colin Murphy, deputy director of the U.S. Davis Policy Institute; and speaking for hydrogen, Toyota’s Craig Scott.

Schaeffer, Mr. Diesel, made the case for the incumbent fuel driving longhaul trucking. He said recent advancements have made diesel much cleaner than in the past, and that about half the commercial vehicles on the road today are now using the newest generation technology.

He argues diesel will remain the dominant future fuel of longhaul transport because it’s widely available, and performs well. Diesel-fueled trucks will cost less to purchase than those running alternative fuels, they offer fleets the flexibility needed to cover a full range of applications, and they command the greatest resale value.

“Diesel checks a lot of boxes other alternatives are going to find very difficult to meet,” Schaeffer said.

Even in California, the most aggressive jurisdiction in pushing zero-emissions transport, Schaeffer noted only 40% of Class 8 trucks sold will have to be zero emissions by 2035, meaning most new trucks sold there will still be diesel-powered.

And while some well-known mega-fleets are early to adopt battery-electric trucks, Schaeffer noted the vast majority of trucks belong to small fleets with 20 or fewer trucks who will be more risk-averse.

But, countered Colin Murphy, from the battery-electric corner, Diesel cannot ever be a zero-emissions option, and climate change demands transport emissions be fully – not partially – eliminated, as soon as possible.

“Climate change is no longer a future problem,” he argued. “It’s no longer something we can figure out, when is the right time to absorb the cost?”

Murphy said electrification “has the best pathway to get to zero [carbon].”

He pointed to early adopters of battery-electric trucks who are proving its viability today. “The technology is not speculative,” he said. “It’s actually in use and growing rapidly.”

While battery costs remain high, electricity itself is cheap, Murphy said. And batteries are heavy, yes, but the weight gain is countered by removing the diesel engine, transmission and other components, and most trucks rarely run at maximum payloads anyways.

“Because electric is the quickest, cleanest best possible way of getting to zero, it’s ultimately going to win this fight,” Murphy argued.

Craig Scott entered the ring from hydrogen’s corner. He said fuel cells are “very scalable and easily adapted to different applications.”

The cost of hydrogen has come down significantly over the past decade, he said, noting it’s less expensive than premium gas in the Los Angeles area. He also touted the $300 billion in new investments being injected into the sector by 2030.

Scott said hydrogen fuel cell trucks are running today, hauling 80,000-lb. loads, with 50,000 on-road miles.

“I’d venture to guess that’s more than any other fleet of zero-emissions trucks in the world,” he said of the trucks built by Paccar with Toyota for use at U.S. West Coast ports. “It’s not a science experiment, it’s ready today.”

Other advantages of hydrogen include refueling times that rival diesel, and a 500-mile range with diesel-type performance in any weather condition.

Mr. Battery-Electric, Murphy, countered that those trucks have bulky hydrogen tanks on the rear of the cab where a sleeper would be needed for longhaul routes.

“That box behind the cab is entirely filled with hydrogen tanks and batteries,” Murphy said. “What’s the value proposition when they get long range, but sacrifice the space used for a sleeper? I don’t know that a 500-mile truck without a sleeper cab is all that useful.”

Scott countered that a sleeper can still be accommodated on a hydrogen fuel cell truck. When facing criticism about the long fuel times required by battery-electric trucks, Murphy said there are battery swap-out stations in China, where a depleted battery pack can be replaced with a fully charged one in two minutes.

From the hydrogen corner, Scott noted start-up Better Place tried that concept, and has since converted a failed location into a car wash.

“Battery swapping is a silly idea that’s never going to go anywhere,” he quipped.

Mr. Diesel, Schaeffer, also took some shots at hydrogen. “Hydrogen has always been right around the corner,” he said. “As long as I can remember, for 30-plus years, it has always been right around the corner. There’s plenty happening there, but we are not going to be there yet [in 2030].”

Schaeffer said there are 52 hydrogen filling stations in California, but only one in New York City, and none in Georgia or Pennsylvania, “which are pretty big trucking places, last I checked.”

Turning his attention to battery-electric, Schaeffer questioned whether the power grid can support widespread electrification.

“If we don’t decarbonize the grid, none of this matters,” acknowledged Murphy. “That’s essential to having any sort of solution to climate change.”

But he said most of the cost related to decarbonizing the grid will fall on peak demand users. “Most people don’t need to refuel their trucks precisely in that four-hour slot,” he said.

Murphy also took a shot back at diesel. “What is the internal combustion engine’s pathway to zero?” he asked. “There is no way petroleum can get to zero. And there’s no way to produce enough biofuels that are zero carbon.”

Schaeffer, backed against the ropes, responded “That premise is the thing that gets us into trouble – we assume these changes are going to happen overnight. It’s not going to happen that way. The change doesn’t happen overnight. To suggest we will get rid of diesel because of some fractional level of carbon emissions is not realistic. By 2030, this technology is still going to be there.”

Mr. Hydrogen, Craig, acknowledged “the 2030 time frame [being debated] makes it difficult to argue against you.”

But he also questioned whether drivers, who are in short supply, will agree to drive diesel-fueled trucks in the future when alternatives give them a better driving experience, with less noise and vibration.

“How does the industry recruit drivers in the world of diesel when they’re expecting more comfort?” he asked.

Instead of changing the fuel, Schaeffer replied, industry should look to how else it can become more efficient.

“Having autonomous trucks may be more valuable to the industry than trying to change all the fuels and technologies in the next 10 years,” he said.