Hydrogen Internal Combustion Engines and the Case for Technology Neutral Transport Policy

by Allen Schaeffer (Engine Technology Forum) Why emerging hydrogen engine programs and a growing industrial ecosystem expose the risks of regulating drivetrains instead of emissions outcomes

For much of the past decade, transport policy has been guided by a simplifying assumption: achieving decarbonization requires the wholesale replacement of internal combustion engines (ICE) with battery‑electric or fuel‑cell vehicles. That assumption has shaped regulations, subsidy structures, and public messaging across the U.S. and Europe. Yet in 2026, this framing is increasingly misaligned with engineering reality – particularly in heavy‑duty transport and off‑highway sectors.

Hydrogen internal combustion engines (hydrogen ICEs), once dismissed as a transitional curiosity, are now revealing the limits of policies and regulation based on drivetrain architectures rather than emissions outcomes.

Crucially, this reassessment is being driven not by startups or speculative prototypes, but by established global technology leaders whose business models depend on durability, serviceability, and regulatory clarity.

Decoupling Combustion from Carbon

When fueled by hydrogen, internal combustion engines emit no carbon dioxide at the tailpipe. From a climate perspective, they behave very differently from gasoline or diesel engines, even though they share similar mechanical principles. Yet many regulatory frameworks still treat “combustion” as a proxy for “carbon,” creating blind spots for technologies that separate the two.

This matters because many of the assumptions underpinning transport policy are now being reexamined. EV adoption has slowed in the U.S. and parts of Europe, grid constraints are tightening, and charging infrastructure rollout remains uneven – particularly outside urban corridors. At the same time, heavy‑duty, long‑haul, and off‑highway applications remain difficult to electrify without operational penalties. These pressures have already forced policymakers to revisit earlier positions, including the EU’s effective 2035 ICE ban, which has shifted toward lifecycle‑based emissions logic rather than absolute drivetrain prohibition.

MAHLE: Resolving the Technical Objections

One of the longest‑standing objections to hydrogen combustion has been technical: concerns that such engines cannot deliver diesel‑equivalent torque or comply with tightening nitrogen oxide (NOx) limits. In April 2026, MAHLE Powertrain directly challenged that narrative by demonstrating a heavy‑duty hydrogen ICE operating at diesel‑comparable torque levels while achieving very low NOx output.

This matters because torque is what defines usability in trucks, construction machinery, and generators. MAHLE’s work suggests that modern combustion control, injection strategies, and aftertreatment can reconcile performance with air‑quality compliance.

The implication is uncomfortable but important: regulatory frameworks that exclude hydrogen ICEs on technical grounds are already outdated.

Volvo: Proving Vehicle‑level Credibility

Technical feasibility becomes policy‑relevant only when it translates into real vehicles, and this is where Volvo Trucks has played a decisive role. Volvo is now road‑testing hydrogen combustion trucks in long‑haul configurations, explicitly targeting segments where battery‑electric solutions struggle due to range, refueling time, or infrastructure constraints.

By integrating hydrogen ICEs into truck platforms rather than treating them as experimental side projects, Volvo has reframed the technology as a potential compliance pathway rather than a loophole.

For regulators, this raises a critical question: if a vehicle delivers zero tailpipe CO₂, meets criteria‑pollutant limits, and performs its intended duty cycle, on what basis should it be excluded from eligibility?

Cummins: Scaling Hydrogen Combustion

If MAHLE validates the physics and Volvo validates the vehicle, Cummins validates the system. Cummins has embedded hydrogen combustion into its fuel‑agnostic engine strategy through platforms such as the B6.7H and the X15H. Built on the same core architecture as Cummins’ diesel and natural‑gas platforms, transmissions, cooling systems, service tools, and much of the manufacturing infrastructure can be shared, preserving established manufacturing and service ecosystems, reducing the risk of stranded industrial assets. For OEMs and fleets, this dramatically lowers the cost and complexity of adopting hydrogen.

Cummins has also invested in hydrogen‑specific components, including turbochargers optimized for hydrogen combustion and certified for future Euro VII emissions standards. This ecosystem approach signals long‑term commitment rather than a demonstration project. Cummins’ hydrogen projects – supported in part by government‑backed initiatives such as the UK’s Project Brunel – demonstrate that hydrogen ICEs are moving beyond prototypes into certifiable, supportable products.

FPT Industrial and Caterpillar: The Off‑highway Reality Check

Perhaps the strongest argument for technology‑neutral policy comes from sectors often ignored in passenger‑vehicle‑focused regulation: agriculture, construction, mining, and stationary power.

FPT Industrial has already deployed hydrogen ICE variants of its XC13 engine in off‑road equipment such as snow groomers, where high power density, long operating hours, and rapid refueling make batteries impractical. Caterpillar, meanwhile, has advanced hydrogen combustion in large‑bore engines for power generation and industrial applications, including generator sets capable of running on high hydrogen blends or 100% hydrogen.

These use cases highlight an uncomfortable truth: entire categories of equipment central to food production, infrastructure, and energy security have no realistic all‑electric substitute. In these contexts, excluding hydrogen combustion is not climate‑ambitious – it is climate‑counterproductive.

The final signal comes from Tenneco, a major Tier‑1 supplier, that has expanded hydrogen‑specific testing and materials development for combustion engines, focusing on durability, embrittlement resistance, and high‑temperature tribology. Tenneco’s work suggests that hydrogen ICEs are entering a phase where component standardization, certification, and long‑term service life are credible concerns. That alone should green light regulatory pathways rather than close them.

The Takeaway: H2-ICE is Advancing – Can Our Policies Evolve Too?

Taken together, developments at MAHLE, Volvo, Cummins, FPT Industrial, Caterpillar, and Tenneco point to a simple conclusion: combustion is no longer synonymous with carbon. Hydrogen ICEs will never dominate passenger cars, but in heavy‑duty, off‑highway, and industrial sectors, they offer a realistic path to decarbonization that aligns environmental objectives with operational reality.

Decarbonization is ultimately an outcomes problem, not an architecture problem. Policies that pre‑select technologies risk locking in inefficiencies just as engineering solutions are expanding. Hydrogen internal combustion engines may be uncomfortable for existing regulatory categories – but that discomfort reflects the need to update the categories, not eliminate the option. READ MORE