Breakthrough in carbon dioxide removal: researchers aim to utilize stones to extract CO2 from Earth's atmosphere.

Chemists from Stanford University have developed a simple and cost-effective method for removing carbon dioxide (CO2) from the Earth's atmosphere using an unexpected source: stones. The authors of the study note that the technology is quite straightforward and potentially inexpensive, but it will need to be scaled up to achieve significant results, according to IFLScience.

The technology involves heating ordinary minerals to transform them into materials that spontaneously extract carbon from the planet's atmosphere and permanently store it. Even more astonishing is that the reactive materials can essentially be produced in standard kilns, such as those used in cement manufacturing.

Currently, scientists are focused on finding ways to remove CO2 from the Earth's atmosphere using engineering systems, but they often concentrate either on improving or scaling up direct air capture technologies. These systems use large fan panels to push surrounding air through chemicals or utilize other processes to extract CO2. While the technology is constantly being refined, it remains limited due to high energy costs. As a result, researchers are seeking alternative approaches, turning to the planet's vast reserves of silicate minerals.

According to Matthew Kanan, a professor of chemistry at Stanford's School of Humanities and Sciences, there is an inexhaustible supply of minerals on Earth that can remove carbon dioxide from the atmosphere. Unfortunately, these minerals do not react quickly enough to address the issue of greenhouse gas emissions. The team notes that their new work solves this problem in a scalable manner.

Silicates are a common group of rock-forming minerals that make up the foundation of the Earth's crust and mantle. When reacting with water and atmospheric CO2, silicates form stable bicarbonate ions and solid carbonate minerals in a process known as weathering.

While the natural process could take hundreds to thousands of years, the researchers in this new study have found a way to significantly accelerate the reaction. The team developed an entirely new process to convert slowly weathering silicates into much more reactive minerals that capture carbon more rapidly and store it more effectively.

Professor Kanan states that he and his colleagues were able to present a new chemistry for activating inert silicate minerals through a simple ion-exchange reaction. The team was surprised by how effective the new technology turned out to be.

In their efforts to combat global warming, the researchers emphasize that we will need to radically reduce our dependence on fossil fuels and permanently remove billions of tons of carbon from the atmosphere. This new development could help achieve that goal.

The new approach was inspired by an old method and requires only half the energy used by leading direct air capture technologies. The scientists also believe that the technology could be cost-competitive. The process begins with heating limestone in a kiln, converting it to calcium oxide, which is then mixed with sand to become a key component of cement.

During their laboratory studies, the team employed a similar process but replaced sand with another mineral containing magnesium and silicate ions. Upon heating, the minerals exchange ions and become magnesium oxide and calcium silicate, two alkaline minerals that react quickly with acidic CO2 in the air.

The study's authors tested the technology in the lab and then in natural conditions: the process took several weeks to several months, which is still thousands of times faster than conventional weathering.

Today, Kanan's lab produces about 15 kilograms of material per week, but the researchers believe their development could eventually be scaled up to millions of tons per year.