Producing hydrogen cheaply through simplified electrolysis

April 28, 2015 by Laure-Anne Pessina, Ecole Polytechnique Federale de Lausanne
Producing hydrogen cheaply through simplified electrolysis
Credit: EPFL/Jamani Caillet

A simplified and reliable device developed at EPFL should enable hydrogen production at low cost. Researchers were able to perform water electrolysis without using the expensive membrane placed between the electrodes in conventional systems.

Many scientists dream of replacing fossil fuels with hydrogen. As hydrogen does not emit carbon dioxide, it is an ideal transportation fuel and mean for storing the renewable energy of intermittent resources such as sunlight and wind. However, , which consists of "splitting" water molecules into hydrogen and oxygen with electrical power, remains challenging, as it is far too expensive to compete with conventional energy sources.

At EPFL, the team headed by Demetri Psaltis has come up with a system for producing hydrogen through a simplified and versatile process of water electrolysis. By playing with the balance between fluid mechanic forces, the researchers showed that it was possible to do without the expensive membrane that sits between the electrodes in the traditional systems. This discovery was recently published in Energy and Environmental Science.

A revolutionary microfluidic demonstrator

In a conventional system, two electrodes are submerged in water and separated by a . An electric current is sent through one of the electrodes (the cathode) and then travels to the other (the anode). The current, with the help of a catalyst, causes the to break apart into oxygen and . To prevent the two gases from mixing together and making an explosive mixture, polymer membranes are implemented between the catalysts to keep the gases separated.

In both research and industry, membranes used for ionic conductivity are most commonly made of Nafion, due to its great stability and ion conductivity. However, they are expensive, have a limited lifetime and only work in highly acidic solutions, which limits the choice of catalysts.

To rid themselves of these constraints, the scientists placed the electrodes less than a few hundreds micrometres apart in a microfluidic device. When the liquid moves above a certain speed between the electrodes, the gases are pushed in opposite directions - thanks to the lift forces caused by an effect known as Segré-Silberberg effect - without the need for a membrane to guide them into separate outlets.

This design sets the stage for the production of devices that work with all types of liquid electrolytes (containing ions) or catalysts, since there is no longer the risk of damaging the components due to a highly acidic environment. This versatility is not possible in conventional systems, in which only catalysts made of noble metals like platinum can work with the low pH values imposed by the membrane. "Our device has the potential to surpass the performance of a similar water-splitting apparatus that relies on an ion conductive membrane. This is due to the higher ion conduction in liquid electrolytes than in common solid membranes", says Mohammad Hashemi, the first author of the paper.

The same team is now working on scaling up the design for higher production rates. As the only dimension that needs to remain small is the inter-electrodes distance, it is possible to implement the same concept using high surface area as side walls of narrow electrolyte channels."

Explore further: Clean energy future: New cheap and efficient electrode for splitting water

More information: A membrane-less electrolyzer for hydrogen production across the pH scale, Energy Environ. Sci., 2015, Advance Article, DOI: 10.1039/C5EE00083A

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5 / 5 (1) Apr 28, 2015
This design sets the stage for the production of devices that work with all types of liquid electrolytes (containing ions) or catalysts,

Now this is three kinds of awesome. And with the extreme closeness of the electrodes it even reduces the footprint of bulk hydrogen producing facilities.
2.5 / 5 (2) Apr 28, 2015
STill need clean input energy from massive amounts of solar, wind, or hydro power to complete the cycle.
not rated yet Apr 28, 2015
This could possibly be directly implemented into solar panels themselves.

Doesn't have to be....This could be built anywhere with access to the grid and draw power in times of surplus to stabilize it (and give off energy via fuel cells in times of shortfall). An ideal buffer system that#d need next to no maintenance now that it uses no acid and no membrane that is eventually broken down.

(And I'd really like to see this in a way where you could refuel your car at home off cheap grid energy. Toyota already has a hydrogen car out with 430miles range)
5 / 5 (2) Apr 28, 2015
I still want to know how they actually get the gases separated. No membrane in the middle is great but what keeps them from mixing again as soon as it leaves the actual area of the plates?
not rated yet Apr 28, 2015
I have heard it suggested that the fall in oil prices may be due to investors factoring in the advent of new technologies such as this, and today I also see "Audi creates green 'e-diesel fuel of the future' using just carbon dioxide and water", and of course new oil fields also seem to be found regularly.
The energy to drive these new processes, for me, would be nuclear, but that is sure to upset a lot of folk.
Apr 28, 2015
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