Hydrogen is the buzzword in energy circles now.
You can make it by electrolysing water and, if the electricity used came from renewable sources, it’s effectively emissions free. When you use hydrogen in a fuel cell to generate electricity or fuel a vehicle, nothing comes out the tailpipe except water vapour.
So, why aren’t we using it already? Well, there are some technical challenges to overcome, such as storage and transport.
How can we store and transport hydrogen?
Like natural gas, hydrogen needs to be stored either in high pressure tanks, or liquefied and stored in cryogenic tanks. And, like natural gas, hydrogen can explode. While hydrogen is safely managed by trained professionals in an industrial setting, there may be concerns about usage of large quantities of hydrogen in urban environments.
Researchers around the world are looking for ways to store and transport hydrogen as safely as possible. One way is by attaching the hydrogen to a carrier liquid – something that is stable at normal operating conditions. This liquid can be stored and transported using standard fuel tanks and trucks similar to our existing petrol or diesel infrastructure.
Our researchers are building a hydrogen generator, which can recover hydrogen from a liquid carrier, to address the storage and transport challenge.
What challenge will the hydrogen generator solve?
Liquid organic hydrogen carriers (LOHC) are organic compounds that can absorb and release hydrogen through chemical reactions. LOHC may include chemicals such as methanol, toluene or benzyl toluene.
The use of LOHC to store and transport hydrogen has been investigated for more than 30 years. But research has escalated in the last few years as the world turned to hydrogen to help solve the net zero challenge.
Using an LOHC as part of the hydrogen supply chain entails a number of steps:
- Hydrogen is produced, for example by electrolysis of water using renewable energy.
- Hydrogen is added onto the LOHC by a process called hydrogenation. This is usually done at the point of hydrogen production.
- LOHC is stored and transported to where the hydrogen will be required. It is stored at the destination until it’s required.
- Hydrogen is retrieved from the LOHC via a process called dehydrogenation. This is where our hydrogen generator fits in.
- Hydrogen is then used as a fuel. This can be creating electricity in a fuel cell, or directly in a combustion engine or furnace, or used as a chemical reagent.
- LOHC is returned to the location of hydrogenation, to be reused.
This hydrogenation/dehydrogenation cycle produces zero GHG (greenhouse gas) emissions.
The technology is already established for the hydrogenation step (step two above). But, until recently, there have been no commercial dehydrogenation processes for these hydrogen carriers, especially for small to medium scale decentralised applications. Our hydrogen generator solves that problem, effectively completing the LOHC use cycle.
It enables power generation where you need it, like a diesel generator. But without the carbon dioxide and particulate (mixture of solid particles and liquid droplets found in the air) emissions!
What makes the hydrogen generator work?
The hydrogen generator we plan to build will use our patented technology: Catalytic Static Mixer (CSM). Our CSM is a 3D printed scaffold with a catalyst coating that fits neatly into standard pipes. The structure is designed to optimise interaction between reagents, so the catalytic reaction is most effective.
The CSM allows better process control than a conventional packed bed. When the catalyst is exhausted it’s relatively simple to switch the CSM out with a new one, and then regenerate the old one. This technology is also highly scalable – you simply increase the number of CSMs in parallel flow.
The CSM technology is central to the hydrogen generator. The LOHC flows through and around the CSM, connecting with the catalyst. The catalyst removes the hydrogen from the LOHC and forms bubbles of hydrogen gas.
How big will the hydrogen generator be?
The project has two parts. First we will build a pilot scale hydrogen generator. Then we will use what we have learned to build a demonstration scale hydrogen generator.
The pilot unit will produce 5 kg of hydrogen per day. We anticipate it will be about 1m x 2m, so it will be able to sit on a bench.
The demonstrator unit will produce 20 kg of hydrogen per day – a good size for a hydrogen refuelling station. The size is expected to be the size of a standard 12m shipping container.
Australia’s National Hydrogen Strategy estimates 1 kg of hydrogen can be used to travel 100km in a Hyundai Nexo or power a 1400watt electric split-cycle air conditioner for 14.5 hours.
What are some potential uses of this technology?
A hydrogen generator of this size is ideally designed for off-grid power supply – effectively replacing some diesel generators. It could be used on farms, mine sites, exploration sites, country festivals, and anywhere else an off-grid power supply is required. It could also be useful for hydrogen refuelling stations for hydrogen-powered cars.
By replacing diesel generators, a hydrogen generator will reduce GHG emissions and may even be quieter!
How could this technology contribute to a low-carbon economy?
Getting to net zero emissions is a wicked problem, and there is no single answer. This technology could provide a solution for off-grid power requirements. These include hydrogen refuelling stations, medium sized worksites, and diesel generators in some of the hard to abate sectors including farms and mine sites. In doing so, it will help get hydrogen into the hands of everyday Australians.