Hydrogen engine retrofits: feasible or fairy tale?

The question of whether hydrogen can be credibly retrofitted to existing marine propulsion plants has, for much of the past decade, attracted more aspiration than engineering substance. That picture is beginning to change.

Maritime technology startup Newlight Marine Technologies has completed Factory Acceptance Testing (FAT) of a hydrogen retrofit package applicable to both two- and four-stroke main engines, conducted under the supervision of class society RINA. The results indicate that the transition from prototype to shipboard installation is now a matter of engineering execution, rather than a theoretical possibility.

Using the Newlight system, existing diesel engines can operate on a blend of hydrogen and conventional fuel, reducing carbon emissions without replacing the entire engine. The technology is positioned as a retrofit plugin rather than a powertrain replacement, deploying an engine control unit that monitors operating conditions in real time and optimises the hydrogen-diesel mixture dynamically across varying load profiles.

Co-founder and CEO, Haran Cohen Hillel, is direct about the operational intent: "We designed the system for enginerooms, and the package is ready to move from the factory floor to vessels. Users will immediately see less fuel per nautical mile and lower emissions without any downtime or sacrificing performance."

The FAT programme was conducted over four days and exercised the full operating sequence of the hydrogen injection system end-to-end, covering safety layer architecture, control and monitoring logic, electrical integration, and engine behaviour under representative duty profiles. The package was validated against the International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels and assessed against RINA class rules for hydrogen-fuelled ships.

Co-founder, Evyatar Cohen, described the engineering discipline behind the safety architecture: "From the moment the system vents to the moment it injects, every step is validated, logged, and recoverable. Operators get straightforward modes, dependable changeover to conventional fuel, and a retrofit that drops into existing machinery without the need for any vessel modifications."

“The package is ready to move from factory floor to the vessels”

A four-stroke engine operating as a genset was tested at a shore-based facility and a two-stroke engine was configured as main propulsion during an open-water sea trial. The dual-cycle scope is significant: slow-speed two-stroke engines dominate deep-sea commercial tonnage, while four-stroke medium-speed engines are ubiquitous across both propulsion and auxiliary generating plant. A validated retrofit solution that addresses both architectures within a single package has considerably broader commercial application.

Demonstrated capabilities included precise hydrogen-blend injection timing, load tracking under open-water conditions, continuous thermal and emissions monitoring, and seamless changeover between conventional fuel and hydrogen, with no engine downtime.

Workshop trials conducted ahead of the Lomarlabs collaboration demonstrated fuel consumption savings of up to 30%, with average reductions of 20% anticipated across in-service operational profiles. Stated performance metrics include CO2 reductions of 15-20% per voyage, with a typical retrofit installation window of two weeks.

Newlight now moves into Harbor Acceptance Testing under RINA supervision, coinciding with the commissioning of the first commercial vessel installation. Engineering integration work covering interfaces, pipework routing, and commissioning procedures has been completed in collaboration with the naval architectural firm Aurelia, while Lomarlabs has provided access to operational vessels and maritime expertise to accelerate the shipboard transition.

The broader question this development poses is one of supply chain readiness. The combustion-side engineering challenge is evidently tractable. The harder constraint, as hydrogen-blend operation moves toward commercial scale, will be the availability, bunkering infrastructure, and cost trajectory of marine-grade compressed hydrogen at the ports where ships operate.