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AspiraDAC’s modules were developed by Southern Green Gas and the University of Sydney. Professor Deanna D’Alessandro oversees the university’s Sydney Sustainable Carbon group, which won a $250,000 grant from XPRIZE and Elon Musk’s philanthropic research fund last year to further develop the technology.

“At the heart of the direct air capture process is a porous material. It’s a very highly specific sponge for carbon dioxide,” D’Alessandro said.

Solar panels inbuilt into the machines power both stages of the carbon capture. Fans draw air into the modules, which strip out C02. Once the sponges are saturated, they’re heated, which releases the C02. AspiraDAC would then compress the gas and pump it deep underground at a suitable site, such as a drained oil reservoir.

Critics of carbon capture and storage say it allows oil, gas and coal projects a get-out-of-jail free card to continue mining and burning fossil fuels. Many have failed to meet their carbon-capture goals and often the captured C02 is used to force more oil out of the ground, negating the carbon drawdown.

Direct air capture differs from point source capture, which refers to projects that catch emissions directly from a carbon-emitting project such as a coal-fired power plant.

“It’s very important just to distinguish the fact that it does not involve point source capture of carbon dioxide, that it directly addresses the very critical and urgent need to remove historical emissions of human emissions and carbon dioxide from the atmosphere,” D’Alessandro said.

The world’s biggest DAC project, Climeworks’ Orca facility, is perched on an Icelandic lava field and powers its air-sucking fans with geothermal energy. Orca can remove 4000 tonnes of carbon dioxide from the air each year.

Climeworks just announced the construction of another DAC facility in Iceland, Mammoth, that could draw down 36,000 tonnes of carbon a year for permanent storage.

The technology is still prohibitively expensive and currently captures an inconsequential amount of carbon dioxide compared to the billions of tonnes belched by the burning of coal, oil and gas.

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But scaled-up direct air capture will be needed to scrub the atmosphere of carbon if we have any chance of restabilising the climate in coming decades, said D’Alessandro. Other carbon capture measures are needed, such as planting trees, but D’Alessandro points out you’d need a forest the size of NSW to negate just two years of Australia’s carbon emissions.

“The Intergovernmental Panel on Climate Change has scientifically demonstrated that we need to be removing at least 10 gigatonnes of carbon dioxide per annum by mid-century,” said D’Alessandro.