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10 August 2022

Capillary action presents new generation of ultra-efficient electrolysis

By Harry Morgan

An Australian start-up, claiming to be able to develop the world’s cheapest green hydrogen, has secured $29.4 million in its Series A funding round. Hysata believes that its capillary-fed design will produce the world’s most efficient electrolyzer, even at pilot manufacturing facilities.

The company’s technology boasts a 95% system efficiency, meaning that just 41.5 kWh of electricity is required to produce one kilogram of hydrogen. This undercuts the industry benchmark figure of 50 kWh per kilogram and delivers a “step change in performance over incumbent technologies,” according to Hysata.

Given that the higher heating value (HHV) of hydrogen sits at 39.4 kWh, denoting how much energy hydrogen releases when combusted, most electrolyzers today typically operate at an efficiency of 75%, using 52.5 kWh of electricity per kilogram. State-of-the-art asymmetric polymer electrolyte membrane electrolyzers only reach an efficiency of 83%.

Hysata’s approach supplies water to the electrodes of an electrolyzer via a capillary-induced transportation system. Water is delivered along a porous separator, eliminating any bubbles that may otherwise be eroding efficiency at the electrodes. Bubbles in an electrolyte fluid are non-conducting; when they stick to electrodes during operation, they prevent the contact between the fluids and the electrodes that is needed for electrolysis to take place.

Hysata’s technology could present the next iteration of electrolysis development. In the 1970s, zero-gap electrolysis meant that the anode and cathode were in direct contact with the separator membrane – boosting efficiency as bubbles were only able to form on one side of each electrode. PEM electrodes then followed, allowing the cathode to run without an electrolyte, producing hydrogen gas without bubbling it through a liquid – again boosting efficiency.

In experiments published the journal Nature, an alkaline capillary-fed electrolysis cell using this approach was able to achieve an efficiency of 98% (a cell voltage 1.51 volts at 0.5 Amps per square centimeter at 85 degrees Celsius). Using an electrolyte reservoir at the bottom of the cell prevents contact with both electrodes until it is drawn up using capillary action. Just enough electrolyte has direct contact with only one side of the electrodes, without any bubbling occurring.

The cost of electricity currently accounts for around half of the total cost of hydrogen production. As electrolyzer manufacturers reach economies of scale over the coming decades, this figure could rise as high at 90% – even despite the continuing reduction of renewable energy prices. With such a dependency on fuel costs, savings in electricity consumption will have huge ramifications on the cost of available hydrogen on the market.

With Hysata aiming for gigawatt-scale production by the middle of the 2020s – citing its mass-manufacturable, modular design – the company is aiming to deliver hydrogen for less than $1.50 per kilogram within just a few years. At this price, the cost of green hydrogen will be competitive with grey hydrogen – produced using natural gas – and will sit far below blue hydrogen, which is relying on unproven carbon capture technologies.

The improved efficiency also reduces the amount of water used in hydrogen production, while the simplicity of plant balancing will also help reduce the overall costs of the hydrogen produced, according to Hysata, with less cooling required. There’s no need for liquid circulation, gas-liquid separator tanks, piping, pumps and fittings; the system can be air-cooled, cutting down further capital and operating costs.

Another way to look at this is the boost that such technology gives to the broader build out of hydrogen in a clean energy economy. The amount of renewable power generation capacity needed to produce sufficient green hydrogen has been marked as one of the key barriers to its success in achieving global decarbonization. Current electrolysis technology means that 14 GW of wind and solar capacity is needed to produce of 1 million tons of green hydrogen per year. Using Hysata’s CFE, just 11 GW is needed, meaning around $3 billion is saved in capital costs.

By 2035, Rethink Energy anticipates that global demand for green hydrogen will reach 171 million tons per year. Using Hysata’s approach, rather than existing designs, this could free up 513 GW of renewable energy capacity, or save over half a trillion dollars in the capital required to produce this hydrogen.

Hysata has been developed as a spin out of the University of Wollongong in Australia, which developed the technological breakthrough. It’s oversubscribed Series A funding round secured funding from Clean Energy Finance Corporation, Kiko Ventures (Australia’s largest steelmaker), IP Group Australia, Vestas (Danish wind turbine maker), Hostplus, and BlueScope.