The energy value of hydrogen is 39,4 kWh per kilogram, but creating it with a current electrolyser costs about 52,5 kWh. An Australian company called hysata claims that his new cell reduces the energy cost to 41,5 kWh and beats efficiency records, while also being cheaper to install and operate.
The company promises green hydrogen at around € 1,50 per kilogram in a few years. The research is published in the open access journal Nature Communications.
Efficiency: a big obstacle for hydrogen
Greater efficiency would allow for more energy to be stored and support rapid refueling: in other words, it would make hydrogen competitive and widespread on the market.
If Hysata's new electrolyser technology delivers on its promise, the efficiency of the electrolysis process will significantly increase, making better use of the precious clean energy. This equipment can really bring the price of green H2 down to the point where it becomes competitive with dirty hydrogen or even fossil fuels.
How does an electrolyser work today?
In early versions, the anode and cathode were both immersed in the electrolyte, causing bubbles to form around them. In the 70s, zero-gap electrolysis connected the anode and cathode directly to the separating membrane, resulting in higher efficiency (with bubbles only on one side). The polymer electrolyte membrane (PEM) method, first developed in the 70s and early 80s, has progressively allowed the cathode side of a battery to function without an electrolyte. This further increased efficiency by producing hydrogen gas without bubbling it through a liquid. But that's still not enough.
How does the Hysata electrolyser device work?
Hysata's electrolyser cell takes things to the next, and perhaps ultimate, level. A reservoir at the bottom of the cell keeps the electrolyte out of contact with both the anode and cathode until it is drawn through a porous, hydrophilic interelectrode separator, using capillary action. The electrolyte therefore has direct contact with the electrodes, but only on one side, and both hydrogen and oxygen are produced directly, without bubbles being in the way.
Resistance is further reduced due to the fact that no water is drawn in from the side of the electrode that is releasing gas, so the two do not get in the way of each other and as the water is electrolyzed out of the separator, the capillary action draws higher from the tank to replace it.
Hysata's team claims its "capillary" electrolyser has record efficiency of 98%, far superior to that of a "commercial polymer membrane electrolyser", which has achieved an efficiency of 83%. The technology also reduces ancillary costs: no liquid circulation is needed, no tanks that separate gas and liquid, or pumps, or fittings are needed.
Add up all the components, the overall efficiency is 95%. Its energy 'cost' is 41,5 kWh / kg. The average efficiency of any other electrolyser is 75%.
What can change with this system
For hydrogen producers, an electrolyser like this could significantly reduce both the capital and operational costs of producing green hydrogen. An epochal transition, such as the transition to electric starting from the combustion engine.
The CEO of Hysata Paul Barrett, says the company will commercialize the technology and "giant-scale hydrogen production capacity by 2025". Hysata is building a pilot plant for the production of the electrolyser, and will make several hires already this year.
A good shot in the context of a real "green gold rush". The competition to get hydrogen into thegreen economy turns on, and a cheaper and more efficient electrolyser would be in great demand.
