Sizing combined gas for internal combustion engines: why PEM and alkaline aren't interchangeable.

Two different volume pictures.

Alkaline electrolysis produces oxyhydrogen using a liquid potassium hydroxide (KOH) electrolyte bath. It scales well to high-volume industrial applications, and decades of use — including our own on-road testing — have established practical volume benchmarks for specific engines and flow rates in that context.

PEM (proton exchange membrane) electrolysis produces the same kind of combined H₂/O₂ stream, but through a different process — a solid polymer membrane rather than a liquid electrolyte bath. One direct consequence: no liquid caustic electrolyte means no electrolyte mist carried into the gas stream, and a resulting gas purity of 99.991%.

Measure it on the actual equipment.

As with any combustion-enhancement application, the most reliable way to confirm the right unit for a specific engine and duty cycle is a field trial — measuring real results on the actual equipment, rather than assuming a figure from a different technology carries across unchanged.

• · Fleet trial programme — baseline, controlled fitment and reporting.
• · Installation guide — step-by-step fitting guidance.
• · PEM vs alkaline — servicing, handling and cost comparison.
• · PEM electrolysis — stack, water treatment and control detail.

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.

Questions.

Is alkaline electrolysis a bad technology?

No. Traditional alkaline (Brown's Gas) electrolysis is a well-established, effective technology with a long track record in combustion enhancement, and at industrial scale — large boilers and thermal plant — it is genuinely well suited to the task. That is not in question. The narrower point on this page is about how the volume specification for an internal combustion engine differs depending on which technology produces the gas.

Why can't I use an alkaline litres-per-hour figure to size a PEM unit?

Because how much combined gas an engine needs for a given effect is not purely a function of displacement — it also depends on the purity of the gas delivered. A contaminated stream carries a smaller effective proportion of active combustion-enhancing gas per unit volume; a clean, high-purity PEM stream does not. Treating the two as directly interchangeable on a litres-per-hour basis risks over- or under-sizing the unit for the application.

What purity does PEM deliver?

99.991%. There is no liquid caustic electrolyte in a PEM cell, so there is no electrolyte mist to be carried into the gas stream.

So how is the HydroHub™ range specified?

Against engine capacity — litres of displacement — rather than against a fixed gas-volume benchmark carried over from alkaline systems. The sizing logic has to account for the technology actually producing the gas.

How do I confirm the right unit for my engine?

A field trial. As with any combustion-enhancement application, the most reliable confirmation is measuring real results on the actual equipment and duty cycle, rather than assuming a figure from a different technology carries across unchanged.