Carbon-capture breakthrough could be a game-changer in utilising CO₂

Its inventors say it’s the most cost-effective method of capturing CO₂ yet devised. In the short term, they hope their Airthena device will be used to produce the 100 million tonnes of CO₂ that Australia imports each year.

“CO₂ is used in the horticulture industry, it’s used in building manufacturing, it’s used in soft drinks, and it’s used in the chemical industry,” says chemical engineer Associate Professor Matthew Hill, who helped develop Airthena.

At present, the cost of CO₂ is about A$300 a tonne, but the new technology can capture the gas from the atmosphere for about $100 a tonne, he says.

A demonstration Airthena unit can capture six kilograms of CO₂ every day; the unit is two metres square, and can run off a solar cell.

“We’ve run more than 1000 cycles of that, so it’s very effective,” says Dr Hill. “What we really need to do is go from six kilograms per day to six tonnes per day.”

The developers are in discussions with industry partners and investors, and hope to finalise plans to scale up the technology in the near future.

In the longer term, if the cost of capturing the CO₂ becomes lower still, the technology could be used to capture the excess carbon produced when fossil fuels are burned.

“If we start to utilise the CO₂, we’re creating an economic opportunity,” Associate Professor Hill says. “We’re creating jobs, and just as a lucky benefit on the side, we’re mitigating against climate change.

“I think that we learned – and especially where the economy is now – that jobs are the No.1 priority, and it just turns out that this technology can actually create jobs, because CO₂ is a valuable molecule that can be used in a whole variety of ways.”

The device could be adapted so that greenhouses capture their own CO₂, for instance. Or the CO₂ could be used to feed algae (which is then used to make biofuel), or to make sustainable cement.
A framework that acts ‘like a sponge’

The device uses a metal organic framework (MOF) made practical by the work of chemical engineer Dr Munir Sadiq.

The MOF acts “like a sponge, and it’s very good at soaking up just the carbon dioxide”, Associate Professor Hill explains. “Although CO₂ concentrations are increasing, there’s only 0.04% of CO₂ in the air, so you need to have a very selective way of capturing it.”

He says that five years ago, he believed – as many still do – that direct air carbon capture technology was a “pipe dream”.

“We did the work anyway, and we’ve just found that it works a lot more efficiently than we had imagined. So, if you can capture the CO₂ from the air, and it’s cheaper than buying it in, then straight away you’re onto a winner, and it gives you options.”

The federal government’s Technology Investment Roadmap identifies five technologies as key to supporting the economy and lowering emissions: hydrogen, carbon capture and storage (CCS), soil carbon, storage options, and “low carbon” steel and aluminium production.

If the roadmap is approved by the Senate, these five technologies will attract $18 billion in Commonwealth investments over 10 years.

Dr Sadiq says federal funds will help increase the efficiency and economic viability of his research.

When he developed a CO₂ filter for his PhD, Dr Sadiq’s particular interest was in capturing CO₂ in a way that was economically viable.

“If you’re capturing carbon dioxide from a coal-fired power plant that produces 100 megawatts of electricity, for example, the cost of capturing the carbon would consume 40 megawatts of electricity,” he says. “That has made it completely unattractive to investors, and to owners of such facilities. There’s no incentive, cost-wise, to do it.”

He says his method can reduce the 40 megawatts by 45% (or to 30 megawatts), and he’s confident future improvements will take this down to 15 megawatts.
Petroleum, steel industries will benefit

Much of the public discussion around carbon capture focuses on electricity, but the petroleum and steel industries could also benefit from a technology that lowers carbon emissions, he says.

“Petrochemicals also come from hydrocarbon. A lot of our medications come from petrochemicals. A lot of our normal household materials come from petrochemicals. We cannot simply replace them.

“Or look at iron ore, stainless steel processing. We still don’t have that renewable energy technology that will process our iron ore into the finished material.”

A Swiss company, Climeworks, also captures CO₂ from the atmosphere. Dr Sadiq says his method is more energy-efficient, and has the advantage that it can be powered by renewables.

He’s optimistic that his research could make a positive difference – if it receives the necessary funding.

“We hope to go to a much better version of the Airthena where we’ll do a lot of optimisation. Then, we think we will have a game-changer.”

“If we threw the kitchen sink at this, we would probably have something within a couple of years,” Associate Professor Hill says.

Source: Monash University, press release, 2020-11-17.