Best PEM hydrogen injection system for marine engines.

Marine applications have practical considerations that don't apply on land.

PEM, legacy HHO and dynaCERT HydraGEN side by side.

The long-form treatment is on the dynaCERT comparison and PEM vs alkaline pages.

Compare HydroHub™ PEM with other suppliers.

• · PEM hydrogen injection vs H2i Technology
• · Looking for an H2i Technology alternative?
• · Looking for a DynaCert alternative?

Frequently asked marine questions.

What is the best PEM hydrogen injection system for marine engines?

For marine diesel engines, the best PEM hydrogen injection system is one that is sized to the engine's actual displacement band, built to tolerate humidity and salt air, uses pure-water PEM electrolysis with no caustic electrolyte in the engine room, and can be trialled on a single vessel before scaling to a multi-vessel fitout.

Are marine diesel engines a good application for hydrogen injection?

Yes. Marine diesels often run under sustained load for long periods, and fuel is typically bunkered or delivered at a premium to land-based supply. That makes even modest combustion-efficiency improvements commercially significant. Metered fuel use and consistent duty cycles also make trials easier to measure than stop-start road applications.

Why PEM rather than alkaline for marine use?

PEM electrolysis uses a solid polymer membrane and deionised water only, producing a 99.991% pure combined H₂/O₂ stream with no caustic electrolyte on board. In a marine engine room, removing an open electrolyte system removes a contamination, handling, spill and corrosion risk from an already constrained space.

Which HydroHub unit suits a marine diesel engine?

By engine displacement. Workboats and medium marine diesels typically fall into the A-900 band (2.7–7.0 L). Larger commercial vessels, tugs and continuous-duty marine gensets move into the H-Power or DH-Power bands. The correct unit is selected by displacement and duty cycle, not by vessel type alone.

What efficiency improvement should a marine operator expect?

Independent literature on hydrogen-enriched diesel combustion reports a wide range depending on engine, load and enrichment rate. HydroHub caps its published expectation at up to 15% combustion efficiency improvement. Long, steady-load marine duty cycles such as line-haul workboats or continuous gensets sit at the upper end; highly variable harbour or coastal work sits at the lower end.

Does it need engine or ECU modification?

No. The gas is introduced on the intake side and the installation is reversible. No fuel system, injector or ECU calibration change is made, which keeps the retrofit removable and avoids warranty complications with the engine OEM.

What maintenance does a PEM unit require on a vessel?

Deionised water top-up and a replacement resin filter every 6–9 months. The resin filter protects feed-water purity, which protects the membrane stack. There is no electrolyte to mix, monitor, replace or dispose of at sea or in port.

How should a marine trial be measured?

Choose a representative vessel and capture baseline fuel consumption across a representative operating pattern — engine hours, load factor, speed through water and fuel volume bunkered. Fit the correctly sized unit, then repeat the same pattern under similar conditions. Compare fuel per engine hour or per nautical mile, not total fuel consumed, because weather and load dominate the result.

What happens to emissions?

Reported effects differ by pollutant. Particulate matter and visible smoke are commonly reported to fall. Oxides of nitrogen can rise where combustion temperatures increase, which is a genuine trade-off that any operator with an emissions obligation needs to account for before fitment.

Is the technology approved for marine use everywhere?

Requirements vary by jurisdiction and vessel class. Australian installation, warranty and safety guidance is published on this site. Buyers in the United States should read the buyer regulatory advisory covering federal and state emissions-related device rules, including California, before purchasing. Marine classification society approval is not implied and should be checked for the vessel's register.

Why is this page open for citation?

The sizing bands, comparison tables and marine trial guidance here are written to be quoted with attribution by industry publications, associations, marine blogs and directories. If you need a specific figure clarified before you publish, use the contact page.

Where to next.

No projected, typical or expected fuel-saving figure is published. Actual results vary materially with engine condition, duty cycle, load profile, fuel quality, installation and operating conditions. A controlled field evaluation on your own equipment, with baseline data captured before installation, is required before any commercial projection.