When we think of combating climate change and reducing global carbon dioxide emissions, we often envision renewable energy sources, electric vehicles, and rewilding projects. But, there is another powerful tool to combat climate change right beneath our feet: rocks.
Rocks have naturally been removing CO2 from the atmosphere for thousands of years through a process called mineral carbonation. In this process, CO2 undergoes a chemical reaction with oxides found in nature to produce new, stable minerals that remove CO2 from the atmosphere. This process occurs naturally, but slowly. By accelerating this process, we can harness the power of rocks to remove CO2 on a much faster timescale.
The $100M XPRIZE Carbon Removal competition incentivizes innovation in carbon dioxide removal (CDR), including rock-based methods, and encourages innovators to join this global movement and help move the needle on CDR solutions. In this way, XPRIZE hopes to pave the way for a more sustainable future and mitigate the impacts of climate change.
ROCK-BASED CDR SOLUTIONS
Rock-based methods can be divided into two broad categories: those that happen deep underground (known as in-situ mineralization) and those that happen above ground by exposing crushed rocks to CO2‐bearing gases (known as ex-situ or surficial mineralization).
In-situ, underground, mineralization involves injecting CO2 deep underground into geologic formations of reactive rocks for permanent storage. The CO2 reacts with these rocks to form durable minerals that lock the carbon away for millennia. The challenge with these methods is ensuring the CO2 remains sequestered, and thus these projects require close monitoring to ensure they work as designed.
Ex-situ, above-ground, mineralization is also commonly referred to as enhanced rock weathering (ERW). This technique involves crushing rocks and spreading them over large land areas. Rocks commonly used for this include basalt and olivine. As rainwater and CO2 interact with the crushed rocks, a chemical reaction converts the aqueous carbon dioxide into stable minerals. The resulting carbonates are then stored in the ground, effectively removing excess carbon dioxide from the atmosphere.
ERW not only sequesters carbon but adds a secondary benefit by replenishing vital nutrients to the soil, promoting healthier plant growth. This contributes to the sustained, overall health of the area and its ecosystem.
IMPACT OF CDR METHODS
Using rock-based CDR methods has a number of unique benefits including scalability and permanence. Unlike other carbon removal solutions that rely on complex infrastructure, rock-based CDR, especially ex-situ mineralization, can be implemented in various locations around the world. Additionally, once the carbon dioxide is converted into stable minerals, it remains locked away for geological timescales, providing a long-term solution for carbon storage.
It's important to note that rock-based CDR, like all CDR methods, is not a singular solution to our climate challenges. CDR methods must complement other mitigation strategies and emission reductions in order to effectively reduce atmospheric CO2.
Large-scale implementation of these methods will require significant investment in research, development, and infrastructure. This growth is being driven by XPRIZE Carbon Removal and the competing teams.
ROCK-BASED CDR IN XPRIZE CARBON REMOVAL FINALS
Out of the 1,300 teams from 88 countries that competed in the XPRIZE Carbon Removal competition, XPRIZE chose 20 finalist teams to move on to the last leg of the competition, including six Rock track teams: Arca, Lithos Carbon, Mati Carbon, Silicate Carbon, UNDO Carbon, and Yuanchu Technology. This final phase before the competition’s end included site visits to see the innovative technology in action and undergo robust validation procedures.
Rock-based methods offer a promising and innovative approach not only to remove carbon dioxide from the atmosphere but also contribute to the creation of sustainable and resilient ecosystems.
Learn more about these competing teams and their technology in our recently released Rock track episode of our XPRIZE Carbon Removal docuseries. New episodes will be released weekly, covering each of the prize tracks. Stay tuned!
THE AUTHOR
