PEM Hydrogen Injection System
A PEM hydrogen injection system splits purified water into hydrogen and oxygen on demand and feeds the mixed gas into the engine's intake air. It is not a fuel replacement: the gas is a combustion promoter introduced at a small fraction of the total charge, generated only while the engine is running.
Technical explanation
The core of the system is a proton-exchange-membrane stack: a solid polymer electrolyte sandwiched between catalyst-coated electrodes. Direct current from the vehicle's 12 V or 24 V supply drives water splitting at the anode; protons migrate through the membrane and recombine with electrons at the cathode to form hydrogen. Because the electrolyte is a solid polymer, there is no potassium hydroxide bath, no caustic liquid on the vehicle and nothing to decant or dispose of.
Water quality is the limiting variable. Deionised or distilled water is circulated through an inline resin filter that holds conductivity low and protects membrane life; the filter is a service item replaced every six to nine months. Gas production is interlocked to engine operation by a vibration sensor, so no hydrogen is stored anywhere in the installation and output stops the moment the engine stops.
Combustion effects
Hydrogen has a laminar flame speed roughly an order of magnitude higher than diesel vapour and a far wider flammability range. Present as a minor fraction of the intake charge, it seeds ignition across more of the cylinder volume and shortens combustion duration, so a greater share of the fuel burns near top dead centre where it does useful work rather than late in the expansion stroke.
The consistently reported outcomes are reduced unburned hydrocarbons, reduced carbon monoxide and lower smoke opacity at mid to high load, with improved brake thermal efficiency in most bench work. The trade-off is NOₓ: higher peak temperature can increase NOₓ formation depending on load and injection timing, so operators in NOₓ-regulated duty must measure rather than assume.
Application-specific notes
- Output is matched to displacement: 450–900 ml/min covers 1.0–7.0 L, heavy-duty units serve larger engines
- Installation is non-invasive — no injector, ECU or fuel-system modification, and fully reversible
- Compatible with DPF, SCR, EGR and urea after-treatment
- Steady-load duty cycles show the clearest, most repeatable results
What Is PEM Hydrogen Injection? — Combustion Enhancement Overview
Explainer covering pure-water PEM electrolysis, on-demand H₂/O₂ generation and how the gas is introduced upstream of combustion in a diesel or petrol engine.
Specify a HydroHub™ PEM system for your engine
Hardware-only supply, free worldwide delivery (DDP), and output matched to engine displacement. Buy the unit and run your own trial — no evaluation contract required.
Questions.
Does a PEM hydrogen injection system store hydrogen?
- No. Gas is produced on demand from purified water and consumed immediately in the intake stream. There is no pressurised hydrogen vessel in the installation.
Does the engine need a remap?
- No. The gas is introduced upstream of combustion and fuel delivery and engine management are left untouched, which is what makes the installation reversible.