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HYDROGEN STORAGE ISSUES BEING ADDRESSED
Fuel-cell vehicles need safe, lightweight hydrogen storage tanks.

 

Hydrogen fuel cells are touted as the best solution for electric 4WDs and RVs, because battery packs are just too big, too heavy and take too long to charge. However, hydrogen tanks are also too heavy and lack capacity. How about powdered hydrogen?

 

 

At Outback Travel Australia we’ve been monitoring alternative propulsion systems for many years: ever since it became obvious that fossil fuels would be gradually phased out of mainstream motoring.

Several 4WD makers, including Ineos, with its new Grenadier, have stated that they will introduce hydrogen-fuel-cell vehicles, while Toyota and Hyundai already have hydrogen passenger cars in customers’ hands.

 

 

Battery vehicles work fine for short-distance travel, but have serious range issues for long-distance and remote-area travel. Fuel cell vehicles, powered by hydrogen offer much better range, but there’s still the issue of fuelling and storing gaseous hydrogen.

Hydrogen is packed with energy – 33.3 kWh/kg, almost three times that of petrol – but needs around 700 bar pressure at low temperatures for feasible on-vehicle storage. The gas is also extremely inflammable and prone to leaking, particularly at such high pressures.

 

 

We’ve been keeping track of alternative storage and transport methods since 2008, since which time the brightest prospect seemed to be metal hydride storage. However, systems like GKN’s Hy2Green design that it launched in 2019 looked a tad heavy for vehicle use.

GKN’s low-pressure concept works by chemically-bonding hydrogen molecules within a metal compound structure.  Metal hydride storage systems typically operate at 10-40 bar, which is up to 20 times less than typical high-pressure systems, but weigh around the same as equivalent-energy lithium batteries.

 

 

Powder power – a simple, efficient route to hydrogen fuel

 

 

In June 2008 we came across an article in the Royal Society of Chemistry journal Energy & Environmental Science. The story reported that chemists in the US had developed a simple reaction to make ammonia borane – a powder more hydrogen-dense than even liquid hydrogen. 

Ammonia borane (AB) is a stable white powder which releases hydrogen gas upon heating. Its use as a hydrogen storage material was hampered by difficulties in making the powder in reasonable yield, but research was ongoing.

We’d almost forgotten about ‘hydrogen powder’ until Deakin University researchers made a breakthrough in July 2022. The new process was first described by nanotechnology researchers from Deakin’s Institute for Frontier Materials (IFM)  in the journal, Materials Today.

 

“Right now, Australia is experiencing an unprecedented gas crisis and needs an urgent solution,” Alfred Deakin Professor Ying (Ian) Chen, IFM’s Chair of Nanotechnology, said.

“More efficient use of cleaner gaseous fuels such as hydrogen is an alternative approach to reduce carbon emissions and slow global warming.”

Traditional oil refinery methods use a high-energy ‘cryogenic distillation’ process to separate crude oil into the different products used by consumers, including petrol and diesel. This process makes up a huge 15 per cent of the world’s energy use.

The IFM research outlines is a mechano-chemical way of separating and storing gases, which uses a tiny fraction of the energy and creates zero waste.

The breakthrough is so significant and such a departure from accepted wisdom on gas separation and storage that lead-researcher Dr Srikanth Mateti said he had to repeat his experiment 20 to 30 times before he could truly believe it.

“We were so surprised to see this happen, but each time we kept getting the exact same result.

“It was a eureka moment,” Dr Mateti said.

 

 

The special ingredient in the process is boron nitride powder, which has a large amount of surface area for gas adsorption.

“The boron nitride powder can be re-used multiple times to carry out the same gas separation and storage process again and again,” Dr Mateti said.

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

“Boron nitride is classified as a level-0 chemical that is deemed perfectly safe to have in your house. 

“This means you could store hydrogen anywhere and use it whenever it’s needed,” he said.

 

 

During the process, boron nitride powder is placed inside a ball mill – a chamber containing small stainless-steel balls – along with the gas that needs to be adsorbed.

As the chamber rotates at a higher and higher speed, the collision of the balls with the powder and the wall of the chamber triggers a special mechano-chemical reaction, resulting in gas being adsorbed into the powder.

The ball-milling gas adsorption process consumes 76.8 kilojoules to store and separate 1000 litres of gas. This at least 90 per cent less than the energy used in the petroleum industry’s current ‘cracking’ separation process.

Once adsorbed into the powder, the gas can be transported safely and easily. Then, when the gas is needed, the powder can be simply heated in a vacuum to release the gas, in an unchanged state. The IFM team has submitted a provisional patent application for the process.

The breakthrough is the culmination of three decades of work led by Professor Chen and his team and could help create solid-state storage technologies for a range of gases, including hydrogen.

With its current research, the IFM team has been able to test the process on a small scale, separating two to three litres of material. But the team hopes for industry support that will allow scaling up to a full pilot and eventual commercialisation.

“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.”

 

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