October 7, 2022

“Entirely new” mechanochemical breakthrough for hydrogen storage – pv magazine International

Researchers at Deakin University in Melbourne have discovered a new way to separate, store and transport large amounts of gas. The method, they say, is efficient, affordable and creates zero waste, which has huge implications for the burgeoning green hydrogen industry and for the energy transition in general.

Research conducted at Deakin’s Institute for Frontier Materials has discovered a new method called “ball milling” to store gas in a special nanomaterial at room temperature. The method relies on mechanochemical reactions, which means machines are used to produce unusual reactions, and the team believe the discovery could help solve the key challenge of hydrogen storage, which is currently a major hurdle. to adoption.

This breakthrough marks such a departure from the accepted wisdom about gas separation and storage that one of the main researchers, Dr Srikanth Mateti, said he had to repeat his experiment 20 to 30 times before he could really believe it himself.

“We were so surprised to see this happen, but every time we got the exact same result, it was a eureka moment,” Dr. Mateti said.

The special ingredient in the ball milling process is boron nitride powder, which is small but has a large absorption surface.

The boron nitride powder is placed in a ball mill – essentially a mill containing small stainless steel balls in a chamber – along with the gases that need to be separated. As the chamber rotates at higher and higher speeds, the collision of the beads with the powder and the chamber wall triggers a mechanochemical reaction, causing gas to be absorbed into the powder, the researchers explain.

Different types of gases are absorbed into the powder material at different rates, which means that they are easily separated from each other by repeating the process.

“Boron nitride powder can be reused multiple times to perform the same gas separation and storage process over and over again,” Dr. Mateti said.

“There is no waste, the process requires no harsh chemicals and creates no by-products.

“Boron nitride itself is classified as a Level 0 chemical, something that is considered perfectly safe to have in your home. This means you can store hydrogen anywhere and use it whenever you need it.

The researchers described the method as having a “remarkably high gas storage capacity”. This, they say, is due to the new way the gas molecules stick to the powder during the ball milling process, which doesn’t break up the gas molecules.

The gas absorption process by ball milling consumes 76.8 KJ/s to store and separate 1,000 liters of gas. That’s at least 90% less energy than the energy used in the oil industry’s current separation process, known as cryogenic distillation.

Dr. Srikanth Mateti and Professor Ying Chen. The Deakin Institute for Frontier Material team believe this discovery will help overcome the key challenge of hydrogen storage by allowing huge amounts of green hydrogen to be stored and transported safely in solid form at a fraction of the energy cost.

Image: Deakin University

Once a gas, such as hydrogen, is absorbed into the solid-state material, it can be transported easily and safely, the researchers say. When the gas is needed, the powder is simply heated under vacuum to release the gas as is.

This breakthrough is the culmination of three decades of work led by Prof. Ying (Ian) Chen, Chair of Nanotechnology at the Deakin Institute for Frontier Materials, and his team.

“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 hazardous processes and chemicals,” Professor Chen said.

“We’re showing there’s a mechanochemical alternative… It doesn’t require high pressure or low temperatures, so it would provide a much cheaper and safer way to develop things like hydrogen vehicles.”

As it stands, the Deakin team has only been able to test their process on a small scale, separating about two to three liters of material. They hope to attract industry support so that the discovery can be scaled up to a full pilot project.

A provisional patent application for their process has already been filed, with the groundbreaking findings published in the journal materials today.

“We need to further validate this method with industry to develop a practical application,” Professor Chen said.

“To go from the laboratory to a larger industrial scale, we need to verify that this process is economical, more efficient and faster than traditional methods of gas separation and storage.”

Specifically, the researchers said that for the method to scale, they need to perfect the grinding process. “There is a sweet spot in grinding that creates the weaker chemical reactions we want – without producing stronger reactions that can destroy gas molecules,” Professor Chen and Dr Mateti wrote in a paper. accompaniment in The conversation.

“We’ll also need to figure out how to get the best stocking rate for each material based on grinding intensity and gas pressure.”

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