Houston, Texas, USA : Scientists have found a rapid way to produce a mineral, known as magnesite, MgCO3, (magnesium carbonate), in a lab that can absorb CO2 from the atmosphere, offering a potential strategy for tackling climate change. If this can be developed to an industrial scale, it opens the door to removing CO2 from the atmosphere for long-term storage, thus countering the global warming effect of atmospheric CO2.
Scientists are already working to slow global warming by removing carbon dioxide from the atmosphere, but there are serious practical and economic limits on developing the technology. Now, for the first time, researchers have explained how magnesite forms at low temperature, and offered a route to dramatically accelerating its crystallization. A tonne of naturally-occurring magnesite can remove around half a tonne of CO2 from the atmosphere, but the rate of formation is very slow.
By reducing a process that normally takes thousands of years to a matter of days, the research could boost the burgeoning field of carbon capture and storage (CCS).
As the world struggles to cut spiralling greenhouse gas emissions, experts broadly agree that technologies that suck CO2 from the air will be an essential tool to curtail global warming.
Magnesite is a naturally occurring rock used in jewellery and for various industrial processes, and its carbon-storing capacity was already known to scientists.
Every ton of magnesite is capable of removing around half a ton of CO2 from the atmosphere.
However, while previous studies have explored the potential of storing polluting gases in underground rock formations, the potential of these activities is hampered by the time it takes for new minerals to form.
“This is a process which takes hundreds to thousands of years in nature at Earth’s surface,” explained Professor Ian Power, who led the new research at Trent University.
To overcome this issue, Professor Power and his team identified the processes that form magnesite naturally at low temperatures, and then used this knowledge to dramatically accelerate its crystallisation.
Using polystyrene microspheres as a catalyst to speed up the reactions that form this rock, they reduced its creation time to 72 days. The microspheres themselves are unchanged by the production process, so they can ideally be reused.
The whole process takes place at room temperature, making it extremely energy efficient.
“Our work shows two things. Firstly, we have explained how and how fast magnesite forms naturally. This is a process which takes hundreds to thousands of years in nature at Earth’s surface. The second thing we have done is to demonstrate a pathway which speeds this process up dramatically”
“Using microspheres means that we were able to speed up magnesite formation by orders of magnitude. This process takes place at room temperature, meaning that magnesite production is extremely energy efficient.
“For now, we recognise that this is an experimental process, and will need to be scaled up before we can be sure that magnesite can be used in carbon sequestration (taking CO2 from the atmosphere and permanently storing it as magnesite). This depends on several variables, including the price of carbon and the refinement of the sequestration technology, but we now know that the science makes it do-able”. said Professor Power.
“This depends on several variables, including the price of carbon and the refinement of the sequestration technology, but we now know that the science makes it doable”.
These results were presented by the scientists at the Goldschmidt geochemistry conference in Boston.
CCS technologies feature prominently in many plans to reach the targets set by the international Paris climate agreement and avert catastrophic climate change.
However, some prominent scientists have described the expectations placed on them as “seriously over-optimistic” considering the lack of industry-ready procedures.
Despite these misgivings, there is general acceptance that such technologies must be developed
Commenting, Professor Peter Kelemen at Columbia University’s Lamont Doherty Earth Observatory (New York) said “It is really exciting that this group has worked out the mechanism of natural magnesite crystallization at low temperatures, as has been previously observed—but not explained—in weathering of ultramafic rocks. The potential for accelerating the process is also important, potentially offering a benign and relatively inexpensive route to carbon storage, and perhaps even direct CO2 removal from air.”