Science and Technology

Dollar-a-kg hydrogen?

M. Ramesh | Updated on: Nov 07, 2021
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Rejigged electrolyser promises to deliver

What with the global warming concerns, the ‘hydrogen industry’ is exploding and the words ‘green hydrogen’ are on everybody’s lips. But things won’t move much until the costs have been tamed.

The holy grail of the industry is to produce green hydrogen for “$1/kg”, and the general hope is that scale will hammer down costs.

Leaving scale aside for now, can technology provide tailwinds for the ‘$1/kg’ goal? Going by what a Chennai start-up is doing, the answer seems to be ‘yes’.

Prasanta Sarkar, an expert in fluid mechanics, and Rochan Sinha, who has worked on developing materials, have come up with a prototype of an electrolyser that uses no membrane.

Membranes are meant to separate the oxygen and hydrogen produced by splitting water, because if the gases mix there would be an explosion.

As the membranes are expensive, if you do away with them, you save a lot in capital and running costs.

“We re-engineered the electrolyser,” Sarkar told Quantum , explaining that, instead of a membrane, the electrolyser they designed has “thousands of small reactors”.

The website of their company, NewTrace (newtrace.io), states that their electrolysers are “5x cheaper” and, being modular, can scale up to any capacity.

The device features a number of “flow channels” through which water flows; on either side of each is an electrode, made of a nickel alloy.

Sarkar and Sinha have 3D-printed the electrodes.

Otherwise, the science behind the device is the same as in conventional electrolysers. You provide energy to water, it splits into hydrogen and oxygen. In a conventional electrolyser, the membrane keeps the two gases separate — any mixing could cause an explosion.

In the NewTrace electrolyser, there is natural separation using a high flow of the electrolyte in the tubes, and gravity. Since the evolution of hydrogen and oxygen happen at different electrodes, they can simply be flushed out by the force of the electrolyte (sometimes through pores in the electrodes), before they can cross-over and mix.

The hydrogen is also over 99 per cent pure, Sarkar said.

Furthermore, since it is modular, it is quick and easy to replace any faulty part, he said.

The researchers are now working on the ‘proof of concept’ validation.

The prototype is being tested. “We are building a 100 kW electrolyser by 2022, which will produce hydrogen at 1.63 kg/hr; we plan to scale it up to 1 MW by 2025, which will then be capable of producing 18.76 kg/hr,” Sarkar told Quantum .

Published on November 07, 2021

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