A new metallic-alloy coating that researchers claim can almost double the rate of green hydrogen production from an alkaline electrolyser — and potentially halve stack capex cost — could be used in commercially-available systems within two years, Hydrogen Insight has learned.

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The “nanoFlux” coating, developed by UK-based Oxford NanoSystems (ONS), is made from a metallic alloy that is applied to the electrodes in place of the nickel-based coatings typically used in alkaline electrolysers.

The coating encourages the formation of smaller bubbles that move away from the electrodes, instead of fewer, larger bubbles that stick and obstruct the movement of electrons in the system.

This also means that producers can feed higher levels of electrical current through the electrolyser without it overheating.

As a result, the rate of production is greatly improved — meaning that the electrolyser produces more hydrogen over a given period of time compared to a similarly rated equivalent using a nickel-based coating.

Ian Russell, ONS’s CEO, tells Hydrogen Insight that the company’s tests revealed better rates of production than the 50% improvements it had originally publicised.

“Compared to typical nickel-type electrode coatings, the OnS coating can almost double the production capacity, [ie] the rate of hydrogen production, of an alkaline electrolyser stack without any other changes —all other parts of the stack remain the same,” he says.

“Because the coating also costs less than the nickel-type coatings, this means that the capex cost of the stack is reduced by approaching 50% when measured on a $/kW basis.”

But it does not affect round-trip efficiency, measured in terms of energy losses per kWh of electricity delivered to the system. For alkaline electrolysers, this is typically around 80%, meaning that for every 1MWh of electrical input, the equivalent of around 800kWh of hydrogen will be produced.

ONS also found that its metallic-alloy coating costs around 60% less to install than nickel-based equivalents, but pointed out that the coating accounts for just a “few percent” of overall stack costs.

There is currently a global shortage of nickel, a metal used extensively in battery production for electric vehicles, which could lead to a future components crunch as electric vehicle and electrolyser manufacturing ramps up.

Russell would not give any details on the make-up of nanoFlux, but emphasised that no rare platinum group metals (PGMs) — also in short supply — are used.

Two “major” alkaline electrolyser manufacturers are currently testing the technology for “robustness and stability”, Russell added, declining to disclose the companies involved.

But Anne-Sophie Corbeau, global research scholar at Columbia University’s Center on Global Energy Policy, cautioned against over-emphasising the impact of rate of production on overall electrolyser cost, pointing out to Hydrogen Insight that the balance of plant, the parts of the electrolyser system outside of the stack itself, account for 50-55% of costs for a 1MW unit.

Corbeau, who recently penned a blog post about electrolyser production costs, also questioned the assumptions behind the rate-of-production improvements.

“The range of costs for alkaline is pretty large, so we would have to agree on what the reference point is and apply the cost reduction to that one,” she added.

The real yardstick of success would be the LCOH, she said, noting that the coating may add knock-on costs to hydrogen production compared to nickel-based coatings, for example if it did not last as long and curtailed the lifetime of the stack.

Russell told Hydrogen Insight that ONS had carried out durability tests on nanoFlux as part of its testing regime and had found them favourable, but that electrolyser manufacturers are now carrying out their own tests for this purpose.