Carbon emissions are the primary driver of our rising global temperatures, and curbing emissions has been a consistent priority for researchers around the world as we work towards a greener future. While 2020 saw an overall decline in emissions – due predominantly to the pandemic forcing a reduction of travel and industrial operations – the IEA has projected that CO2 emissions will rebound this year as economies launch back into action. According to the group, these emissions will rise by 4.8% as coal, oil and gas see a comeback. Finding technologies to curb our carbon is essential, and attention is turning to projects that make carbon cutting a priority.
One such project is that of Swinburne University of Technology’s Associate professor Tianyi Ma, who is investigating the repurposing of carbon dioxide to make ‘solar fuels’ such as green methane, carbon monoxide and methanol. Ma received an Australian Research Council (ARC) Future Fellowship of more than $937,000 earlier this month for the project and we spoke to him about what’s next and, if successful, what the technology could mean for our carbon emissions.
The power of solar
Solar panels have grown to become a common part of global energy mixes, and projects throughout Australia are now using these units to pursue a two-step solar conversion process – photovoltaics followed by electrolysis – to create green hydrogen. Ma’s technology also looks to harness solar to create clean energy sources, but his tech uses solar energy directly, harnessing a process called photocatalysis in which energy from the sun is chemically converted into secondary energy sources such as hydrogen, or hydrocarbon fuels.
“In my technology, we use what we call a photo-catalyst,” says Ma. “This is to convert the solar energy not into electricity, but into chemical energies to be stored in small molecules such as hydrogen or carbon monoxide. These small molecules are then energy carriers so when they’re burned, they will release the chemical energy.”
“There’s no step to convert the solar energy into electricity,” he explains further. “My technology is converting this solar power directly into chemical energy, capturing it and injecting it into carbon dioxide to effectively convert it into some useful energy small molecules.”
The complete cycle of Ma’s technology for carbon neutrality
Image: Associate Professor Tianyi Ma/ Swinburne University of Technology
The ARC funding will be used to develop the project over the next four years, during which Ma and his team will work to further test the technologies.
“We are collaborating with some local companies and heavy industries that currently release a huge amount of carbon dioxide,” Ma adds. “So in a mining site for example, we’ll capture the CO2 and use our catalyst and the radiation of solar energy to convert it into useful energy molecules.”
When it comes to the catalysts themselves, Ma says the team has a few candidates.
“We use what we call perovskites, which are widely used in solar cells, it’s a kind of metal oxide catalyst,” he says. “They’re semiconductors which are very good at absorbing solar energy, and when solar energy is being absorbed by these semiconductors, the carbon dioxide comes into contact with the surface of the semiconductor and a chemical reaction will happen and we get the product that is the energy molecules – that is the photocatalytic process.”
The Swinburne team already has a prototype developed which they hope to trial soon alongside their collaborating partners. Specifically, the team is working alongside GrapheneX, a carbon nanomaterial producer, as well as the Clayton Hydrogen Technology Cluster – one of 15 renewable energy platforms in the country supported by National Energy Resources Australia.
“Based on our preliminary research we have this catalyst and we have a small prototype which acts as a reactor for the semiconductor to react with the carbon dioxide,” Ma says. “I’m currently expecting that midway through the research we can do a few field trials at our industry partners’ mining sites, trialling this prototype for on-site CO2 conversion to hydrocarbon fuels.”
Ma’s technology has a current energy conversion rate of between 2%-5%. This is compared to the more established technology of photovoltaics, which has a conversion rate of roughly 20%-30% of light into energy. However, Ma says he anticipates that as his technology is developed, it will see higher energy returns to rival that of photovoltaics. When it comes to economic viability, Ma’s tech uses far cheaper materials than those used in solar panels, offering significant savings for investors.
“Solar cells and storage batteries are pretty expensive,” he says, “but the metal oxide we use as a semiconductor catalyst is very cost effective as it’s made from the Earth’s abundant elements.”
If successful, Ma says the project would have significant benefits for Australia’s energy and environmental security, as well as its economic development.
“This project will deliver highly efficient photocatalysts and reaction prototypes for carbon dioxide reduction, so as to relieve greenhouse effect and accelerate the development of large-scale carbon dioxide utilisation for clean fuels,” he says. “The project will promote R&D of new-generation carbon dioxide photoreduction catalysts and techniques, which are highly promising for commercialisation and industry-level application, and put Australia at the forefront of the utilisation of carbon dioxide and clean energy.”
Ma has previously done research into using a photocatalytic process to produce hydrogen from seawater, which was described as ‘among the best catalysts ever reported’ by Baohua Jia, Founding Director of the Centre for Translational Atomaterials when the paper was released in February. Ma’s team is also developing a prototype to pursue this method of hydrogen production.
“In a similar photocatalysis project, we are manufacturing a 100 square metre, two dimensional prototype, that can float on the surface of the water and directly get solar energy and split water into hydrogen,” Ma says. “That means it is 100% solar driven water splitting to generate hydrogen.”
With carbon abatement the mission on everyone’s minds, finding ways to harness these emissions will likely only gain traction in the coming years, and Ma’s project shows the promise carbon holds if we push our research in the right direction.