New Carbon Sorbent Enables Direct Air Capture at Record Efficiency Rate
A recent scientific breakthrough in capturing atmospheric CO2 promises to remove GHG faster, more efficiently, and with less energy consumption than conventional methods by using isophorone diamine as a sorbent. Market observers believe the new method could speed up the commercial viability of DAC solutions as a key element of climate change mitigation.
Direct air capture of carbon emissions is one of several promising approaches for mitigating climate change. Atmospheric CO2 can be locked in through long-term storage solutions or used to produce carbon-neutral fuels for sectors that are difficult to decarbonize, such as aviation.
Under the International Energy Agency’s (IEA) Net Zero Emissions by 2050 Scenario, around 350 megatonnes of air-captured carbon emissions will be used by the middle of the century for the production of synthetic clean fuels whose combustion releases only as much CO2 as was removed from the air for their production. The ability to actively remove carbon from the atmosphere is a key pillar of global efforts to prevent warming from exceeding 1.5° Celsius.
Nevertheless, most existing carbon emissions capture and storage (CCS) technologies have drawbacks, both in terms of efficiency and regarding the speed at which they can be deployed on a scale where they can appreciably lower the global warming impact of greenhouse gases. A new approach for CCS presented by Tokyo Metropolitan University researchers could change that, however. In a paper published on 10 May 2022 in the research journal ACS Environmental Au, the scientists describe a novel approach using isophorone diamine (IPDA) as a sorbent with high absorption/desorption efficiency that can remove more than 99 percent of CO2 under a 400 ppm CO2 flow system.
Rapid and efficient carbon capture
In their article, “Direct Air Capture of CO2 Using a Liquid Amine–Solid Carbamic Acid Phase-Separation System Using Diamines Bearing an Aminocyclohexyl Group”, the Japanese research group, headed by Seiji Yamazoe, explained how the IDPA – a chemical mostly used as a precursor to polymers and coatings – was able to extract nearly all of the CO2 under conditions mirroring carbon emissions concentrations in the Earth’s atmosphere (<500 ppm).
It did so at least twice as quickly as existing systems, including those employing potassium hydroxide and calcium hydroxide, which are less efficient and have higher recovery costs. IDPA, on the other hand, can be reused after being slightly heated, and is therefore suitable for use in a forward-looking sustainable energy system based on circular use of materials.
The researchers at Tokyo Metropolitan University had spent some time studying liquid-solid phase separation systems as a way of achieving direct air capture of atmospheric carbon. In these systems, the air is bubbled through a liquid that reacts with the CO2 in such a way that the non-soluble carbon is precipitated as a solid. This means that the reaction product does not accumulate in the liquid, but can be easily removed, allowing the liquid to be recycled and reused with minimal loss of reaction speed and efficiency.
Miraç Yazıcı, a market research expert based in Liverpool whose tutoring and consultancy company Econscan tracks tech trends, believes that while the IDPA-based technology has some drawbacks, especially when it comes to cost, its efficiency and speed in removing carbon from the air are huge advantages. “This new method is twice as fast as the nearest other removal technique and operates at low temperatures of about 60° Celsius,” he notes. As such, it is certain to be of interest to the operators of the handful of CCS facilities that are already in operation.
Yazıcı mentions two projects that are currently in the news and indicate strong interest in commercializing the capture and usage or storage of GHG emissions. In the UK, Tata Chemicals Europe – a market leader in the production of sodium carbonate, salt, and sodium bicarbonate – inaugurated the country’s first industrial-scale carbon capture and usage plant at Northwich, Cheshire on 24 June 2022, capping a £20 million (€23.2 million) investment that was supported by a £4.2m grant from the British government’s Department of Business, Energy and Industrial Strategy as a contribution to reaching its ambitious net-zero targets.
Only days later, on 29 June, a consortium consisting of Exxon Mobil, Shell, and the China National Offshore Oil Corporation (Cnooc Ltd.) signed a non-binding agreement with the government of China’s Guangdong Province to build a CCS facility that would capture as much as 10 million tonnes of CO2 annually. That is the equivalent of about 0.1 percent of China’s annual emissions, which would make it one of the largest such projects in the world.
Energy efficiency – a game-changer?
“There are new developments and advances almost daily in this area,” says Yazıcı, adding that some components still need to be improved before the technology can make a viable contribution to the problem of atmospheric carbon. Solutions that operate at higher temperatures also have higher energy consumption, and some of them actually burn natural gas as a source of thermal energy, which runs contrary to the aim of GHG removal – or as Yazıcı puts it: “It’s madness.”
That’s one reason why he believes the IDPA-based process is a potential game-changer, since reducing the amount of process heat also means lower energy consumption.
Because the source and amounts of energy required are such important factors in DAC technology, the ability to operate at lower temperatures would bring down the cost of decarbonization. A target price of US$100 per tonne of CO2 captured would make direct air capture commercially viable, but currently, that price is up to six times higher, depending on the solution used.
The price also determines the feasibility of using captured carbon for multiple industrial applications including construction materials; synthetic fuels; chemicals and polymer production; carbonated beverages, or the development of advanced materials like carbon fibers, nanotubes, and fullerenes or graphene.
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