by According to American chemists, an age -old technique for making cement can be the key to large -scale carbon collection.
The first step when making cement includes converting limestone to calcium oxide, heated in an oven to 1400 degrees Celsius. Calcium oxide is then mixed with sand to produce a vital ingredient for cement.
Inspired by this technique, the researchers at Stanford University used a conventional oven to transform common minerals into reactive materials with the ability to pull carbon out of the atmosphere – and permanently sexwestration.
“The earth has an inexhaustible stock of minerals that are able to remove CO2 Of the atmosphere, but they just don’t respond quickly enough to combat human greenhouse gas emissions, “says Matthew Kanan, a chemistry professor of Stanford and an author of the new study, published in Nature.
“Our work solves this problem in a way that is uniquely scalable in our opinion.”
Carbon capture agreement
Most worldwide and national goals of net zero missions require not only to reduce the production of fossil fuels, but also the removal of carbon dioxide (CO2) From the atmosphere. In fact, these goals trust carbon collection and storage technology (CCS).
In the special report of the IPCC 2018 on paths to limit the global heating to 1.5 ° C above pre-industrial levels, almost all modeled routes held when exceeding the 1.5 ° C limit will turn there later To back, by using CCS to reduce the temperature.
But one Nature Study from October 2024 showed that crossing the threshold and returning after that would not result in the same world as just under the temperature limit. Many climate effects are irreversible and others will take decades to undo.
Although many CCS technologies are in development, they have been limited so far. They are either too expensive, too energy-intensive or on a large scale unproven.
Confringing fossil fuel interests remains the most essential step in curbing the climate crisis – but carbon capture technology can still be useful and research continues to exist quickly.
From slow to rapid weathering
The new paper from Stanford University promises great results.
The method essentially accelerates the natural process of silicate reduction. In this process, co2 In the atmosphere, rainwater dissolves to form a weak acid. This reacts with ordinary minerals in rocks called silicates and breaks them in other connections such as bicarbonate ions (HCO3–), which flows in the ocean and store carbon for thousands of years.
However, the weathering process itself can take hundreds or thousands of years. This new research turns up silicates in many more reactive minerals instead, which means that carbon is captured and stored faster.
“We have proposed a new chemistry to activate the inert silicate minerals through a simple ion exchange reaction,” explains Stanford postdoctoral researcher Yuxuan Chen, main author of the study.
They used a similar method such as producing cement in an oven, but instead of mixing calcium oxide with sand, mixed calcium oxide with another mineral composed of magnesium and silicate ions. The heat has catalyzed an exchange of ions, which forms magnesium oxide and calcium silicate: alkaline minerals that respond quickly with acid co2 In the atmosphere.
In a laboratory test, Kanan and the team have exposed the two minerals to water and pure co2. The materials had responded with the CO within two hours2 To form new carbonate minerals. A more realistic test included exposing the minerals to Atmospheric Co2. Although the carbonation process lasted weeks to months, it was still thousands of times faster than natural processes.
The team plans how this approach can be used on an industrial scale. They estimate that it would require a ton of reactive material to remove a ton of CO2 of the atmosphere. However, their lab can currently produce only 15 kilograms of material per week, and in 2024 alone, more than 37 billion tonnes of carbon dioxide were emitted by burning fossil fuels.
It is estimated that 4 billion tonnes of cement are made every year.
Scaling up the carbonation process into meaningfully delaying global heating would require millions – perhaps billions – tons of magnesium oxide and calcium silicate. The team suggests that they can use my waste, which contains suitable silicates, as a large source of raw material.
“Society has already discovered how they can produce billions of tons of cement per year, and cement ovens have been running for decades,” says Kanan. “If we use those lessons and designs, there is a clear path for the useful scale of laboratory discovery to carbon removal.”
He adds: “You can imagine that the magnesium oxide and calcium silicate spread over large country areas to remove CO2 of ambient air.
“An exciting application that we are now testing is to add it to agricultural soil. As they are again, the minerals transform into bicarbonates that can move through the ground and are stored permanently in the ocean. “
