Water Purity and Electrolyte Quality: The Overlooked Variable in Industrial Oxyhydrogen Performance

Why Water Purity Determines Gas Purity

In an alkaline electrolyser, the feedwater becomes the electrolyte solution itself — circulating in a KOH (potassium hydroxide) medium, in direct and continuous contact with both electrodes. There is no membrane isolating the water from the electrode surfaces or the gas-forming reaction. Any dissolved contaminant present in the feedwater therefore enters the electrolyte directly and remains in ongoing contact with the reaction throughout operation.

This is the mechanistic reason water purity translates directly into gas purity in alkaline systems: the feedwater is not a separate utility that happens to sit nearby the reaction — it is a direct, continuous input to the reaction itself, recirculating rather than passing through once.

Three concrete pathways by which feedwater impurity becomes gas impurity:

Contaminant carryover into the gas stream

Dissolved ionic and particulate contaminants — calcium, sodium, carbonate, sulphate, silica — do not remain fixed in the electrolyte. A proportion is carried over into the evolving gas stream at the electrode surface, particularly as electrolyte concentration changes over time or as contaminants accumulate.

Electrode-surface fouling degrading reaction efficiency

Contaminants depositing on electrode surfaces reduce the effective active area available for the electrolysis reaction, lowering conversion efficiency — meaning more electrical energy is required to produce the same gas volume, and the gas produced carries a higher proportion of side-reaction byproducts relative to a clean, stoichiometric H₂/O₂ output.

Progressive electrolyte degradation

Because the electrolyte recirculates rather than being replaced continuously, contaminant concentration compounds over the generator's duty cycle unless actively managed. Gas purity is therefore not a fixed, one-time specification confirmed at commissioning — it is a property that can drift over the generator's operating life if feedwater and electrolyte quality are not maintained.

Feedwater Purity Specification

Electrolyser feedwater purity is conventionally specified by conductivity, since dissolved ionic contaminants directly increase conductivity and correspondingly compromise electrolysis efficiency and gas quality.

Two internationally recognised standards govern demineralised water purity for electrolysis:

A commonly cited rule-of-thumb target across the industry is conductivity below 2 µS/cm (0.2 mS/m). Beyond conductivity, total organic content and total silica are also specified maximum-concentration parameters under both standards, alongside carbonate and sulphate ions, and silicon and aluminium oxides, as contaminants to be avoided.

A Failure Mechanism Specific to Alkaline Electrolysis

Alkaline systems carry a specific vulnerability that membrane-separated (PEM) systems largely avoid: unplanned shutdown can cause corrosion of the electrodes and a measurable reduction in electrolysis efficiency during subsequent operation. Poor feedwater or electrolyte quality compounds this risk, since dissolved contaminants accelerate electrode-surface degradation during any shutdown or low-flow event — not only during steady-state running.

Alkaline electrolysers are additionally described in the literature as having general sensitivity to contaminants that degrade electrolyte or electrode performance beyond conductivity alone — a broader category the industry sometimes refers to as electrolyte "poisons."

KOH Electrolyte Purity: Specification and Rationale

The KOH electrolyte is not a passive medium — it is a continuously recirculating, functional part of the generator, in direct and sustained contact with both electrodes throughout operation. Its purity is a distinct specification from feedwater purity, though the two are linked: feedwater purity governs what enters the electrolyte in the first place; electrolyte purity governs the ongoing chemical environment the electrodes actually operate in.

Three reasons electrolyte purity matters:

Trace metal contamination causes electrode fouling and unwanted side reactions

Iron, chloride, and other trace metallic impurities commonly found in lower-grade industrial KOH can deposit on electrode surfaces or participate in parasitic side reactions, reducing the electrode's effective active area and diverting current away from the intended H₂/O₂-forming reaction.

Chloride content is a specific corrosion risk

Chloride ions are a well-established driver of pitting and stress-corrosion in metallic electrode and cell-housing materials generally. In a system already vulnerable to electrode corrosion during shutdown events, elevated chloride content compounds that vulnerability during normal operation, not only at shutdown.

Carbonate formation degrades conductivity over time

KOH electrolyte absorbs atmospheric CO₂, forming potassium carbonate, which is less conductive than KOH itself. This is a normal, expected aging process in any open or semi-open alkaline system — but the rate at which it happens, and the point at which electrolyte replacement or replenishment is required, is directly affected by both the starting purity of the KOH and the purity of the makeup water used to replenish it.

This preference follows directly from the mechanisms above: higher-purity KOH carries a lower baseline load of the trace metal and chloride contaminants described in points 1 and 2, reducing the rate of electrode fouling and corrosion risk from the outset. It also extends the practical interval before atmospheric carbonate formation degrades conductivity to the point where electrolyte replacement is required. In short — the 90% threshold is the floor for reliable operation, while higher purity directly extends electrode life and lengthens maintenance intervals, for the same reasons purity matters at all.

Consequences of an Impure Gas Stream

Combustion-enhancement effect is reduced or inconsistent

The mechanism underlying combustion-enhancement performance depends on the reactive radical chemistry of a clean H₂/O₂ stream interacting with the primary fuel in the combustion zone. A contaminated gas stream introduces inert or reactive-diluting species that reduce the effective concentration of reactive gas actually reaching the flame — weakening the combustion effect a performance guarantee would be based on.

Accelerated wear on delivery infrastructure

Contaminant carryover — particulate matter, entrained electrolyte mist — can foul flashback arrestors, gas detection sensors, and injection nozzles over time, increasing maintenance frequency and risking degraded performance of safety-critical components if not addressed.

Reduced generator service life

Alkaline systems are already sensitive to electrode corrosion during unplanned shutdown events; sustained operation on poor-quality feedwater compounds this risk across the generator's operating life, independent of any single shutdown event, through continuous rather than incident-driven degradation.

This is why feedwater and electrolyte specification should be treated as mandatory, ongoing operational requirements — verified at commissioning and monitored through an electrolyte management protocol — rather than a one-time pre-installation checkbox.

Why This Matters for Evaluating Any Oxyhydrogen Vendor

A vendor's willingness to specify, measure, and manage feedwater and electrolyte quality is a genuine signal of engineering rigor — and its absence is a genuine gap. A generator that meets its rated output on day one but has no defined feedwater specification or electrolyte management protocol is a generator whose performance is likely to drift, unpredictably, over its operating life. For any plant evaluating oxyhydrogen combustion-enhancement technology, feedwater and electrolyte specification should be a standard line item in technical due diligence — not an afterthought raised only once performance has already degraded.

At YBG, feedwater and electrolyte quality assessment is built into the site survey and detailed engineering stage of every deployment, with pre-treatment (reverse osmosis, deionisation, or equivalent) specified as part of the integration scope wherever the client's existing water source doesn't meet specification.