The iconic two-seat Porsche 911 Carrera reaches 60 mph in just 3.4 seconds and tops out at 182 mph. Ford’s brawny F-450 pickup tows cargo weighing as much as 20 tons. The two vehicles couldn’t be more different, and yet both may end up keeping their internal combustion engines as the industry pivots to electrification — if refiners can perfect a new carbon neutral fuel.
Porsche, Stellantis, Ferrari, BMW and other automakers are taking a hard look at e-fuel, a replacement for gasoline and diesel. E-fuel combines carbon dioxide taken from the atmosphere — or captured at the source, such as at a refinery — and hydrogen obtained from water through electrolysis.
The lure of e-fuel is that, with no changes to the engine, fuel injectors, other components or emissions systems, it enables an internal combustion vehicle to run nearly as cleanly as an EV.
“We will take the approach that it’s e-fuels for engines, not engines for e-fuels, meaning that we are not going to change the hardware to accommodate them,” said Micky Bly, Stellantis’ head of global propulsion systems, at a panel discussion in April at the SAE International conference. Stellantis tested and is validating e-fuel in 28 gasoline and diesel engine families dating back nearly a decade.
While automakers say e-fuel works in today’s engines, refiners have to figure out how to manufacture it at a cost close to gasoline. E-fuel could cost more than $11 per gallon if it were available now, according to a recent study by the International Council on Clean Transportation. Shell, Exxon, Aramco and several smaller refiners are developing e-fuels.
Domestic automakers in North America are relying on the hefty profits generated by supersize pickups and SUVs to fund the electrification of the rest of their lineups. But a battery-electric powertrain in such big trucks — other than niche vehicles — is a nonstarter because it can’t deliver the same kind of towing and hauling capability and driving range on a charge as piston-powered drivetrains.
In Europe, automakers such as Porsche and Ferrari are looking at e-fuel to preserve the character and performance of the sports cars and exotic cars they have perfected over decades — vehicles for which heavy battery packs, short driving ranges and long recharging times would erode their appeal.
The MG Cyberster EV roadster coming this year, for example, weighs 4,800 pounds — about 1,700 pounds more than the lightest Porsche 911.
Two General Motors SUVs illustrate the advantage internal combustion has over electric drivetrains in large vehicles, the Chevrolet Suburban and the GMC Hummer EV.
The Suburban’s turbodiesel six-cylinder engine is EPA-rated at 26 mpg on the highway. Its 28-gallon fuel tank gives it a range of 728 miles between fill-ups, which often take five minutes or less. The GMC Hummer EV can travel 314 miles on a charge. It takes nearly an hour to recharge a Hummer using a DC fast charger.
Connect a trailer and both vehicles lose range, but the effects of hauling extra weight are more severe in an EV.
No automaker has committed to building electric heavy-duty pickups. A recent test of a Ford F-150 Lightning by AAA shows one reason electric powertrains don’t compare favorably to combustion engines in big trucks: “When loaded with 1,400 pounds of sandbags, 110 pounds shy of its maximum capacity, the Lightning’s range dropped from 278 miles to 210 miles, a reduction of 24.5 percent,” AAA reported.
Just this year, GM announced the next generation of its venerable small-block V-8, a new generation of internal combustion-powered heavy-duty pickups and the next generation of its internal combustion-powered big SUVs — the Chevrolet Suburban, GMC Yukon and Cadillac Escalade — investments totaling nearly $2 billion spread across four plants. Someday, these vehicles might burn e-fuel instead of gasoline or diesel.
“We believe that low-carbon and net-zero carbon fuels can play an important role in reducing carbon emissions from all vehicles,” said GM spokesperson Phil Lienert. “GM supports the research, development and use of these fuels to help mitigate climate change as part of a broader set of solutions for the industry as we work towards electrifying the new light-duty fleet.”
To be sure, e-fuel won’t be coursing through nozzles at public stations anytime soon. Refiners have a lot of work to do in perfecting high-volume methods to produce e-fuel in enough quantity and at a comparable cost to gasoline. And there are other issues, too.
For example, producing e-fuel requires a lot of water, which is a scarce commodity in many parts of the world. It also requires electricity from renewable sources.
Bentley CEO Adrian Hallmark told Britain’s Autocar magazine that progress developing e-fuels is exciting, but that it won’t change the brand’s plans to replace internal combustion engines.
“There’s no road map for industrialization at the scale that would be needed for e-fuels to replace fossil fuels,” Hallmark said. “The tech is there, and you could mix regular fuels with e-fuels to reduce CO2, but our view is there would be no chance in the foreseeable future to reach net zero within an acceptable time scale.”
Porsche, on the other hand, invested $75 million in a company that produces e-fuels in Chile.
But one of the biggest obstacles — the compatibility of e-fuels with fossil fuels — appears to already be in automakers’ rearview mirrors. Automakers say e-fuel is a direct, drop-in replacement for gasoline. It does not require automakers to modify engines, fuel system components or emissions systems, a notion that Greg Davis, a mechanical engineering professor at one of the nation’s largest schools for auto engineers, Kettering University, agrees with. Davis has studied alternatives to gasoline, including hydrogen and e-fuel.
“It can be a drop-in replacement that would require very few changes, maybe just a bit of a calibration change,” Davis told Automotive News. “I don’t anticipate any changes to the emissions system or the catalytic converter.”
That’s massively important as the transition to EVs swallows up the majority of product development funds for traditional powertrains.
Speakers at the SAE International panel in Detroit agreed that an internal combustion vehicle running e-fuel could be nearly as clean as a battery-electric vehicle.
But that doesn’t mean pure air — with no CO2, nitrogen oxides and other greenhouse gases — comes out of the exhaust pipes of vehicles burning e-fuel. Far from it, and this where things get complicated. E-fuel is intended to be a carbon neutral fuel, meaning that the CO2 it produces must equal the CO2 required to make and transport it.
To do that, the electricity required to separate hydrogen from water must come from a renewable source, such as a wind turbine, solar panel or a hydroelectric dam.
Using e-fuel in a gasoline or diesel car requires about five times more renewable electricity than running a battery-electric vehicle, according to a 2021 paper in the Nature Climate Change journal, Reuters reported.
There is another potential clean fuel that works in an internal combustion engine that also eliminates nearly all harmful emissions — gaseous hydrogen produced using renewable sources.
Davis, who has tested gaseous hydrogen in an engine, said an internal combustion engine can burn it without having to be heavily modified. The downside, he said, is that like batteries for EVs, hydrogen’s energy density is far lower than that of fossil fuels.
At SAE International, Dan Nicholson, GM’s vice president of global electrification, controls, software and electronics, said hydrogen is very much in the future for large trucks. But not for fueling internal combustion engines.
“We believe the fuel cell is going to win out in the end,” he said. “GM has homegrown technology in both fuel cells and battery-electric technology. We think [fuel cells] work in the over-8,500-pound class for towing applications. It makes sense in three-quarter-ton pickups for a lot of customers who need towing applications.”
As CO2 will be heavily regulated in North America, Stellantis’ Bly said affordable mobility is essential. “I think that the internal combustion engine is going to have a long-term place,” he said. “And we have to prepare for that to switch, whether it’s ethanol or it’s synthetic or e-fuels.”
