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Hydrogen Internal Combustion Engines: A Contender in the Race for Green Transport

20 Sept 2023

In the ever-evolving landscape of sustainable transportation, the debate between battery-electric vehicles and hydrogen-powered technology has been at the forefront. While batteries appear to be leading the charge for passenger cars, the resurgence of hydrogen internal combustion engines (H2ICEs) has captured the attention of advocates for the traditional internal combustion engine (ICE).

A New Player in the Sustainability Game

The Latin adage "Inter duos combatentes, tertius vincit" - meaning "between two combatants, the third wins" - has come to life in the automotive world. As battery-electric enthusiasts spar with proponents of hydrogen fuel cells, the unexpected third player, H2ICEs, has emerged, intriguing many in the industry.

The Fuel Cell Conundrum

As the automotive world witnesses the ascent of electric propulsion, Toyota remains steadfast in its commitment to hydrogen technology for passenger cars. However, this pursuit faces challenges, as incremental advancements in fuel cell technology have yet to deliver the expected leaps. Rivals like Volkswagen and Mercedes-Benz have notably shifted their focus away from fuel cells in passenger vehicles.

Heavy-Duty Transport: The Overlooked Challenge

While the spotlight shines on passenger cars, the heavy road transport sector - comprised of large trucks, buses, and various industrial vehicles - largely relies on big diesel engines, contributing significantly to transportation pollution. This sector seeks rapid solutions for converting these vehicles into low-emission alternatives.

The Case for H2ICEs

Hydrogen internal combustion engines present an intriguing proposition for heavy-duty vehicles. Unlike fuel cells, H2ICEs don't require the complex infrastructure for storing and transporting pure hydrogen, making them a more immediate solution. While not achieving zero-emissions status, they promise a substantial reduction in emissions, comparable to e-fuels.

Investment and Benefits

The European Commission has modified CO2 emissions standards for heavy-duty vehicles, granting zero-emissions status to H2ICEs that use genuinely carbon-free hydrogen. This development opens the door for established carmakers to extend the life of ICE vehicles beyond 2035, provided they run on e-fuels. The investment-to-benefits ratio for H2ICEs in heavy-duty transport is increasingly compelling.

Promising Developments

Projects like the EU-funded H2Engine initiative and innovations by companies like KEYOU, which converts conventional diesel engines into hydrogen-compatible versions, offer practical solutions. German firm KEYOU, for instance, delivers 18-tonne trucks equipped with hydrogen engines that meet Euro VI standards and the EU's CO2 requirements, exempting them from tolls.

Cummins' Contribution

American corporation Cummins offers heavy-duty vehicles equipped with hydrogen internal combustion engines, such as the X15H hydrogen engine for trucks up to 44 tonnes. These engines provide robust performance while addressing emissions.

A Transitory Solution

While H2ICEs appear to be a promising short-to-medium-term solution for slashing emissions in heavy-duty transport, they should be regarded as transitional. The ultimate goal is to pave the way for fuel cells and a greener hydrogen infrastructure.


Hydrogen internal combustion engines may not be the final answer, but they provide a vital bridge towards cleaner heavy-duty transport. Recognizing their potential as a transitory solution will be crucial in the journey towards decarbonization. The time has come to bid farewell to the traditional internal combustion engine and embrace the technologies of tomorrow.

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