Australian researchers have found a novel way to separate, store and transport huge amounts of gas safely that could wind up being the missing piece of the puzzle for renewable hydrogen.
Renewable hydrogen figures enormously in the net zero emissions plans of Australia – particularly in the hard to decarbonise sectors of industry and heavy transport. But storing and transporting large quantities of gases for practical application remains a major challenge.
A team from Deakin University’s Institute for Frontier Materials (IFM) in Melbourne says it has found a new mechanochemical way of separating and storing gases, which is safe, uses a tiny fraction of the energy compared to traditional methods and creates zero waste.
The team says the breakthrough, detailed in the journal Materials Today, is such a departure from accepted wisdom on gas separation and storage that it had to be repeated 20 to 30 times before it could be believed.
“We were so surprised to see this happen, but each time we kept getting the exact same result, it was a eureka moment,” said lead researcher Dr Srikanth Mateti.
“There is no waste, the process requires no harsh chemicals and creates no by-products. …This means you could store hydrogen anywhere and use it whenever it’s needed.”
The breakthrough is the culmination of three decades of work led by Alfred Deakin Professor Ying (Ian) Chen, IFM’s Chair of Nanotechnology, and his team.
The hero ingredient in the breakthrough is boron nitride powder, which is has a knack for absorbing substances, being small, but with a large amount of surface area. It’s also classed as a “level-0 chemical,” something that is deemed perfectly safe to have in your house.
The researchers put boron nitride powder into a ball mill – a type of grinder containing small stainless-steel balls in a chamber – along with the gases that need to be separated.
As the chamber rotates at a higher and higher speed, the balls collide with the powder and the wall of the chamber triggers a mechanochemical reaction resulting in gas being absorbed into the powder.
One type of gas is absorbed quicker, separating it out from the others, and allowing it to be easily removed from the mill. The process can be repeated over several stages to separate the gases one by one.
All up, the process consumes 76.8 KJ/s to store and separate 1000L of gases, which means it uses at least 90 per cent less than the current gas separation process commonly used in the petroluem industry.
Even more significantly, once the gas is absorbed into the powder it gas can be transported safely and easily. When the gas is needed, the powder can be simply heated in a vacuum to release the gas unchanged.
“The current way of storing hydrogen is in a high-pressure tank, or by cooling the gas down to a liquid form. Both require large amounts of energy, as well as dangerous processes and chemicals,” said Professor Chen.
“We show there’s mechanochemical alternative, using ball milling to store gas in the nanomaterial at room temperature. It doesn’t require high pressure or low temperatures, so it would offer a much cheaper and safer way to develop things like hydrogen powered vehicles.
The next step for the IFM team is to gather industry support and scale the process up to a full pilot. A provisional patent application has been submitted for the process.
“We need to further validate this method with industry to develop a practical application,” Professor Chen said.
“To move this from the laboratory to a larger industry scale we need to verify that this process is cost saving, more efficient, and quicker than traditional methods of gas separation and storage.”
