Make like a leaf: converting CO2

Sydney researchers are developing a technology they hope will be used by power stations to capture emissions from burning fossil fuels, allowing for the carbon to be reused while stopping CO2 from entering the atmosphere.

Professor Huang holds the small plates he has developed to capture and convert CO2. Photo courtesy of Luisa Low/University of Sydney.

Many of us will remember learning about photosynthesis in high school science: the process by which the leaves of plants take in carbon dioxide and water, and with the help of sunlight, convert them into glucose and oxygen. Scientists estimate that trees convert between 100-115 billion tonnes of carbon into biomass every year. With the increasing energy needs of modern lifestyles and devices, and the carbon-emitting processes to generate that electricity, combined with the rates of land clearing removing the trees needed to remove that carbon from the air, existing trees are only capable of removing approximately 40 per cent of the carbon currently in the Earth’s atmosphere; consequently, current global carbon levels in the air are the highest in known history, and scientists world-wide have taken it upon themselves to investigate synthetic ways to capture carbon to prevent it from entering the atmosphere.

However, according to a team of researchers at the University of Sydney, current carbon capture methods focus on storage of carbon, not conversion, which they believe is a resource waste because it requires storage facilities, often buried deep underground.

For this reason, the researchers are developing a method for converting carbon dioxide they call ‘carbon photosynthesis’. Their process draws inspiration from leaves to reduce carbon emissions, and uses nanotechnology to develop a method for ‘carbon photosynthesis’ that they hope will one day be adopted on an industrial-scale.

Professor Jun Huang from the University of Sydney’s School of Chemical and Biomolecular Engineering, is developing the carbon capture method that aims to go one step beyond storage, instead converting and recycling carbon dioxide (CO2) into raw materials that can be used to create fuels and chemicals.

“Drawing inspiration from leaves and plants, we have developed an artificial photosynthesis method,” Professor Huang said.

“To simulate photosynthesis, we have built microplates of carbon layered with carbon quantum dots with tiny pores that absorb CO2  and water.”

“Once carbon dioxide and water are absorbed, a chemical process occurs that combines both compounds and turns them into hydrocarbon, an organic compound that can be used for fuels, pharmaceuticals, agrichemicals, clothing, and construction.”

“Following our most recent findings, the next phase of our research will focus on large-scale catalyst synthesis and the design of a reactor for large scale conversion,” he said.

While the research has been conducted on a nanoscale, Professor Huang hopes the technology will one day be used by power stations to capture emissions from burning fossil fuels.

“Our CO2 absorbent plates may be small, but our goal is to now create large panels, similar to solar panels, that would be used by industry to absorb and convert large volumes of CO2,” Professor Huang said.

According to the researchers, CO2 emissions from transport and burning fossil fuels are the main cause of global warming, contributing up to 65 per cent of the total global greenhouse gas emissions. As nations attempt to curb emissions and divest from fossil fuels, Dr Huang feels there should also be an increased focus on carbon capture and re-use to minimise the harmful impact of increased atmospheric CO2.

“The current global commitment to cut carbon emissions by 30 per cent by 2030 is an enormous challenge, and one that will be difficult to achieve given that energy needs are accelerating,” Professor Huang said.

Carbon capture technologies have been around for over 10 years, however they require carbon to be held in deep underground chambers.

“Carbon conversion could be a financially viable alternative as it would allow for the generation of industrial quantities of materials, such as methanol, which is a useful material for production of fuels and other chemicals,” Professor Huang said.

Professor Jun Huang’s research is supported by the Australian Research Council (DP180104010), the Sydney Research Accelerator Prizes (SOAR) and the University of Sydney Nano Institute Grand Challenge program.