Cummins, other hydrogen ICE proponents hoping for zero-emission status

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Updated Jun 24, 2022
Cummins 15-liter hydrogen engine
Cummins recently revealed its 15-liter hydrogen engine at the Advanced Clean Transportation Expo in Long Beach, Calif.

At a time when fleets are looking at all-electric and fuel cell as their only zero-emission options, hydrogen internal combustion may have a shot at joining that elite club – though, getting past gatekeepers in the U.S. and Europe will be anything but easy.

General Manager of Cummins' Hydrogen Engine Business Jim Nebergall told reporters at a recent press event at Cummins’ headquarters in Columbus, Indiana, that hydrogen combustion "would likely be recognized as ZEV" in Europe.

“It’s huge,” Nebergall said of the possibility.

When CCJ asked if lawmakers in the U.S. might follow Europe's lead should hydrogen combustion be designated as zero emissions, Nebergall said, “How does EPA and CARB view the technology? Will they follow a similar approach? They should.”

The reason for a zero designation, Nebergall explained, rests on the capability of hydrogen internal combustion engines (ICE) to drastically cut carbon, a growing requirement championed regularly by influential investment groups and legislators around the globe who seek to control climate change.

“It’s an extremely low reduction in carbon,” Nebergall said of Cummins’ recently announced 6.7- and 15-liter hydrogen engines. “There’s basically no carbon. It’s just NOx.”

And it’s not much. As Nebergall explained in a recent CCJ story, Cummins’ hydrogen engines will “easily see a 75% reduction in NOx from today’s standards.” Steady state cruising on highway delivers “almost no NOx at all,” Nebergall continued.

The numbers look good long before hydrogen makes its way to the engine. From a well-to-wheels perspective, a June 15 data chart released by California Air Resources Board (CARB) shows hydrogen’s carbon intensity dropping to -150, making it a carbon negative fuel.

[Related: Cummins hydrogen engine offers more capability, lower cost over electric]

Cummins hydrogen engine presentationCummins general manager of hydrogen engine business Jim Nebergall talked with reporters recently at the company's headquarters in Columbus, Indiana.Tom QuimbyTo help ensure low carbon intensity scores, Cummins produces renewable or green hydrogen through electrolysis, a growing method that uses electricity from renewable energy sources like solar, wind and hydroelectric to produce hydrogen from water.

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Hydrogen can beat all-electric’s carbon intensity scores, particularly when the grid is powered by fossil fuel sources like coal and natural gas – which tends to be the case across the country. In 2021, 61% of the electricity in the U.S. was produced by fossil fuels according to the U.S. Energy Administration.

It's this kind of carbon-cutting performance that has drawn support for hydrogen combustion in medium- and heavy-duty trucks from legislators in the European Union, CCJ confirmed. But no matter the EU's leanings, CARB and the EPA, both of which have not yet tested either of Cummins' hydrogen engines, are not impressed.

While it's true that carbon reduction is seen by climate protection advocates as a win in reducing damage to the ozone layer and thus stemming climate change, tailpipe emissions of any kind are regarded as a potential problem for local air pollution in communities, especially those in truck-heavy areas like ports.

“Our definition of ZEV only includes vehicles that have zero emissions of any criteria pollutant, precursor to a criteria pollutant, or a GHG,” CARB spokesman Alberto Larios explained. “So, even if the H2 fuel became 100% renewable, the criteria pollutant emissions from the internal combustion engine would still be a problem and preclude it from counting as a ZEV.”

The EPA so far has also nixed the idea.

“Commercial trucks that use hydrogen combustion engines do not count as zero emission vehicle status,” said EPA spokesperson Taylor Gillespie. “This is because the heat and pressure of combustion, combined with nitrogen in the air, produce NOx emissions, and urea-SCR emission controls are still needed (as they are on diesel-fueled engines.)” 

Building the case

When it comes to considering hydrogen ICE as a zero emission option in the U.S. and abroad, Cummins is not alone. Thomas Korn, engineer and founder of hydrogen engine company Keyou in Munich, Germany, supported the idea during the height of the COVID pandemic.

“As a large proportion of the vehicles currently being produced still have combustion engines, the engine itself must become an essential means of combating the climate crisis,” Korn wrote in a June 2020 article posted on, a scholarly publication focusing on scientific, technical and medical topics.

“This has been recognized by the EU, which classifies vehicles with combustion engines as zero-emission vehicles if their emission levels are below 1 g CO2/kWh,” Korn continued. “This is possible by using modern hydrogen combustion engines.”

Achates opposed piston diesel Peterbilt 579 WalmartNearly two months after revealing its near-zero 10.6-liter opposed-piston diesel engine inside the engine bay of a Peterbilt 579 operated by Walmart, the San Diego based company announced that it would be testing hydrogen next.California-based Achates Power, which recently announced the formation of the Hydrogen Opposed Piston Engine Working Group, also expressed optimism in reaching increasingly tough emissions goals with hydrogen combustion.

“It is possible that a hydrogen opposed piston combustion engine would be placed on par with a ZEV powertrain in terms of criteria emissions and net CO2,” said Achates Chief Commercial Officer Laurence Fromm. “The opposed-piston engine would likely have advantages – potentially large advantages – in lower cost to purchase and longer service life.

Fromm cautioned against dismissing internal combustion, the world's long-standing workhorse, as legislators and major manufacturers around the globe increase the pace of emissions reduction. 

“Until, as a society, we’ve established there are capable, practical, cost-effective and durable solutions we would be foolish to abandon any potential solution,” Fromm continued. “It will be a great advance for the world if we have capable, practical, cost-effective and durable battery electric and/or fuel cells solutions that use sustainably sourced, affordable energy in large volumes around the globe.  But until we do, we need to consider solutions that will get much closer to our goals much faster.”

The European-based Hydrogen Engine Alliance, which counts Cummins, Daimler Truck, Isuzu, Webasto, BorgWarner and Bosch among its growing membership, sees hydrogen combustion as a viable option for cleaning up emissions in Europe.

“Indeed the European Commission acknowledges hydrogen engines for [medium and heavy-duty] as zero CO2 emission vehicles given the use of green hydrogen,” said Hydrogen Engine Alliance founding board member Dr. Marco Warth. “A draft for legislation has been prepared, but not yet ratified.”

Fighting the good fight

No matter the progress, convincing legislators to place hydrogen ICE in the mix with zero-emission all-electric and fuel cells has not been easy since they still emit pollutants, albeit at reduced numbers versus conventional diesel and gasoline engines.

Last week, the European Union voted to nix hydrogen and other green ICE fuels in its quest for zero emission cars. CCJ reached out to the EU for comments on hydrogen combustion in commercial trucks but had not heard back by deadline.

In the meantime, decision makers at CARB will continue considering hydrogen combustion one engine at a time.

Cummins 15-liter hydrogen engine driver side rear“The EPA and CARB haven’t processed this technology fully to understand it,” Cummins general manager of hydrogen engine business Jim Nebergall said. “Do they want to call it a ZEV? Do they want to classify it as that? Or is it a partial ZEV? They’re working through that. I think the industry would benefit if they did classify it as [ZEV]."Cummins“Hydrogen combustion vehicles are novel, still emit combustion by-products, and face a range of durability and performance questions, among other policy matters,” CARB Executive Officer Craig Segall told CCJ. “There is an acute need to move towards true zero emission vehicles, though CARB would carefully evaluate any hydrogen combustion vehicles.”

CARB does have a history of extending compliance to some hydrogen engines, though it didn’t exactly go as planned.

“In prior light-duty ZEV regulations, we have allowed internal combustion engine H2 fueled vehicles to earn credits towards compliance, but they were still not counted as actual ZEVs,” Larios explained.

“Our rationale was that a population of such vehicles would be able to run on a more renewable fuel (assuming a future where H2 is produced through a better process to be considered renewable/clean energy) and that they could bolster the demand for H2 infrastructure along with fuel cell electric vehicles,” Larios continued. “No manufacturer ever really used these provisions.”

Cummins, which announced its membership in the Hydrogen Engine Alliance last week, is making its journey to zero emissions by 2050 with a variety of powertrains which in addition to hydrogen ICE include fuel cell, all-electric, propane, natural gas and gasoline.

Cummins has a long history of working with regulators — which in the U.S. includes the EPA and CARB — to help develop tough, clear and enforceable standards that lead to a cleaner, healthier and safer environment,” said Katie Zarich, Cummins director of on-highway communications. “With respect to hydrogen ICE, we continue to share our perspective regarding how this practical zero-carbon technology can help accelerate the adoption of zero greenhouse gas emissions solutions in fleets, which find the familiarity and relative affordability of Hydrogen internal combustion engines very appealing."