Energy

Hybrid solid-state system harvests more hydrogen from water

(From left) Junyoung Kim, Professor Guntae Kim, and Ohhun Gwona are part of the team who developed the Hybrid-SOEC, a more efficient new system for producing hydrogen
(From left) Junyoung Kim, Professor Guntae Kim, and Ohhun Gwona are part of the team who developed the Hybrid-SOEC, a more efficient new system for producing hydrogen
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(From left) Junyoung Kim, Professor Guntae Kim, and Ohhun Gwona are part of the team who developed the Hybrid-SOEC, a more efficient new system for producing hydrogen
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(From left) Junyoung Kim, Professor Guntae Kim, and Ohhun Gwona are part of the team who developed the Hybrid-SOEC, a more efficient new system for producing hydrogen
A diagram outlining the working principle of the team's new Hybrid-SOEC device
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A diagram outlining the working principle of the team's new Hybrid-SOEC device

Clean and plentiful, hydrogen is a promising fuel source, but there are a few problems standing in the way of it becoming mainstream. South Korean scientists have now developed a new system for producing hydrogen from water, which that they say overcomes some of these issues and produces the gas more efficiently than other water electrolysis systems.

The new device was developed by a research team consisting of scientists from the Ulsan National Institute of Science and Technology (UNIST), Korea Institute of Energy Research (KIER) and Sookmyung Women's University, and is based on an existing design called a solid oxide electrolyzer cell (SOEC).

These work like other electrolyzers in that an electrical current splits water into its constituent molecules – hydrogen and oxygen – which can then be harvested. The difference is that in this setup, both electrodes are solid-state, as is the electrolyte that carries the ions between them.

This has a few advantages over systems that use liquid electrolytes – namely, the liquids need to be topped up occasionally, and over time they tend to corrode other components. And since solid-state electrolyzers operate at higher temperatures, they don't need as much electrical energy to function because they can draw energy from that heat.

But SOECs still have room for improvement. There are two main designs that use different electrolytes: One allows only oxygen ions to pass through, and the other only hydrogen ions. In either case, that one-way street limits the amount of hydrogen that can be produced.

A diagram outlining the working principle of the team's new Hybrid-SOEC device
A diagram outlining the working principle of the team's new Hybrid-SOEC device

So the researchers developed a new Hybrid-SOEC, which uses a mixed-ion conductor to transport both negatively-charged oxygen ions and positively-charged hydrogen ions (protons) at the same time. The end result had all the benefits of a solid-state electrolyzer, with improved efficiency.

"By controlling the driving environment of the hydrogen ion conductive electrolyte, a 'mixed ion conductive electrolyte' in which two ions pass can be realized," says Junyoung Kim, first author of the study. "In Hybrid-SOEC where this electrolyte was first introduced, water electrolysis occurred at both electrodes, which results in significant increase in total hydrogen production."

Using the mixed-ion conductor and electrodes made of layered perovskite, the Hybrid-SOEC produced 1.9 liters (0.5 gal) of hydrogen per hour, running at a cell voltage of 1.5 V and a temperature of 700° C (1,292° F). The researchers say that's four times more efficient than existing water electrolysis systems, and after running the device continuously for 60 hours, there were no signs of that performance degrading.

The research was published in the journal Nano Energy.

Source: UNIST

4 comments
Expanded Viewpoint
Wait a minute here, Skippy La Doodah! In any water molecule, there are two, count 'em two Hydrogen atoms and one Oxygen atom, right? So whenever one of those molecules is broken apart, you ALWAYS get two atoms of Hydrogen and one of Oxygen. It matters not which of the two elements is being the target of liberation, you get the other one too. Unless someone can tell me what happens to the other gas to keep it from being harvested, I'm calling B.S. on this story. The article conveniently leaves out the important data about how that intense level of heat is generated. 700 C is not just a warm summer day around these parts here! Randy
Penguin
The biggest barrier to using hydrogen as fuel is, as the lightest element, it needs to be compressed in order to be useful for most things. I'm wondering at what pressure the gas exits the cell?
ljaques
I'm kind of concerned when we start using this kind of tech in a major way. How long will it be before we notice a loss of fresh water, or worse, a loss of ocean water, when it becomes mainstream globally. Fresh water is limited, and oceans are partially the lungs and liver of our planet, so let's not knowingly do them any more damage, please. To start, let's see if this tech can use gray water, then go from there.
WilliamSager
Forgive me if this sounds too good to be true.