Why green hydrogen is considered key to a cleaner future

Hydrogen molecules on green background (aushets)
Image: Shutterstock

By Liz McGrath

In the quest for a cleaner, more sustainable energy future, scientists such as Professor Hongqi Sun are setting their sights on what many consider the “holy grail” of renewables: green hydrogen.

Professor Sun, new to The University of Western Australia (UWA) and its School of Molecular Sciences, is busy building a research team with a focus on finding a catalyst that harnesses solar power to drive the hydrogen production process, making it economically competitive.

“It’s a very, very hot topic at the moment—I think globally most governments are working on promoting green hydrogen and for scientists, the thought of using green energy to produce green energy is the perfect dream,” he says.

“But there are many challenges.”

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The promise of hydrogen

As the most abundant element in the universe, hydrogen can be harnessed from a variety of sources, including water, natural gas, and biomass. It’s beauty lies in its emissions-free nature; when used as a fuel, it produces nothing but water vapour, making it a key player in the fight against greenhouse gas emissions and air pollution.

Hydrogen boasts a higher efficiency compared to traditional fuels, delivering three times more energy per unit weight than petrol and nearly seven times more energy than coal. It’s also more versatile and can be stored, liquefied, and transported through pipelines, trucks, and ships to meet demand.

Its applications span various industries including transportation, chemicals and refineries, and electricity generation. Fuel cells powered by hydrogen are already propelling electric vehicles, providing backup power to critical infrastructure, and heating homes and industrial processes.

Unlike ‘grey’ or ‘brown’ hydrogen, which is typically produced from fossil fuels such as natural gas through a process called steam methane reforming or coal gasification, emitting CO2 at the same time, green hydrogen is produced by splitting water into oxygen and hydrogen gases using an electrical current.

“Solely using electricity from renewable energy sources like solar, wind or hydropower makes it ‘green’ hydrogen production, but doing this on an industrial scale is a huge challenge,” Professor Sun says.

“Technically, yes, we can do it, but we need to reduce the costs. And it’s not only the production challenges but storage, transport, distribution—there are a lot of hurdles that need to be addressed.

“Using renewable energy, for example solar energy, to revolutionise conventional hydrogen production, known as steam methane reforming, also holds great promise.

Professor Hongqi Sun in glasses, blue shirt and jacket (green hydrogen)
Professor Hongqi Sun

Turbo charging the production process

Professor Sun’s fundamental research is centred on developing novel catalyst, light and thermal active nanomaterials that can speed up the process of producing green hydrogen, making it more efficient.

“When photocatalysts are exposed to light, like sunlight, they start a chemical reaction that mimics natural photosynthesis, a process where green plants and certain other organisms transform light energy into chemical energy,” he says.

“We’re trying to create a similar reaction using water, solar energy and perfectly designed chemical catalysts to produce pure hydrogen and oxygen. Such a system is also expected to work for upgrading fossil fuels to produce clean hydrogen.”

The chemical catalysts, he says, are the key to unlocking hydrogen and can be precisely manufactured to convert as much water to hydrogen and oxygen (or water and methane to hydrogen and carbon monoxide) as quickly as efficiently as possible.

While true green hydrogen is still some years away, blue hydrogen—produced via dry or steam reforming using natural gas but with CO2 emissions captured and stored—is seen as a transitional solution to reduce carbon emissions in the hydrogen production process.

Related article: CSIRO launches state-of-the-art hydrogen refueller

The Australian Government’s goal is to become the major global player in the clean hydrogen field by 2030. Clean hydrogen is part of Australia’s Long Term Emissions Reduction Plan, and producing it for under $2 per kilogram (H₂ under 2) a priority stretch goal.

“With our abundant solar energy, wind, and large tracts of available land for harnessing solar energy, we have many advantages when it comes to producing green hydrogen but we’ve got a long way to go,” Professor Sun says.

“If we can jump to directly using solar energy to generate hydrogen, reducing steps in the production and installation processes of solar panels or wind turbos and removing any hidden CO2 from the picture so that we can comfortably claim that what we have is green hydrogen, the rewards will be enormous.

“These tiny catalysts could be the key to unlocking the chemical reactions that we need for this to happen in a cost effective and sustainable way.”

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