Direct air capture breakthrough: turning CO2 into stone and what it means

01The mineralization process for CO2

Carbon sequestration is a natural process of storing carbon in a carbon pool. The mineralization approach takes this natural process and accelerates it dramatically. When carbon dioxide dissolves in water and comes into contact with certain types of rock, it reacts with minerals in the rock to form solid carbonate compounds. This transforms CO2 from a gas into a solid mineral that is permanently locked away.

The chemical reaction is well understood. Carbon dioxide dissolved in water forms carbonic acid, which reacts with calcium and magnesium silicate minerals in the rock. The products are solid carbonate minerals like calcite and magnesite. In nature, this process happens over thousands of years. The breakthrough is accelerating it to a matter of months or even weeks.

The key to acceleration is the rock itself. Basalt, a fine-grained extrusive igneous rock, is particularly reactive because it contains high concentrations of calcium, magnesium, and iron that can combine with carbon dioxide. When CO2-charged water is injected into basalt formations, the mineralization process begins immediately, with measurable solid carbonate forming in a fraction of the time that natural weathering would require.

02How basalt rock stores carbon permanently

Basalt is an aphanitic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava. It is one of the most common rock types on Earth, forming much of the oceanic crust and large portions of continental flood basalts. This abundance matters because any carbon storage solution needs enormous volumes of suitable rock to make a meaningful dent in atmospheric CO2 levels.

The permanence of basalt mineralization is its key advantage. When CO2 reacts with basalt minerals to form solid carbonate, the carbon is locked in a thermodynamically stable solid. Unlike storage in gas form in depleted oil reservoirs or saline aquifers, where CO2 must be contained and monitored for leaks, mineralized carbon in basalt cannot escape. It becomes part of the rock itself.

Iceland has been a pioneer in this approach. The CarbFix project, which injects CO2-charged water into basalt formations, has demonstrated that mineralization can occur in under two years under the right conditions. The 2026 breakthrough extends this approach, achieving faster mineralization rates and expanding the range of basalt formations suitable for injection.

03The 2026 breakthrough and what it improves

The 2026 breakthrough improves on prior mineralization technology in several key areas. The injection process has been refined to achieve faster dissolution of CO2 in water before injection, reducing the energy required per ton of carbon captured. The mineralization rate has been increased through optimized injection pressures and flow rates, achieving measurable solid carbonate formation in weeks rather than months.

The scalability has improved as well. Earlier pilot projects were limited to specific basalt formations with particular characteristics. The 2026 work demonstrates effective mineralization across a broader range of basalt types, including formations that were previously considered unsuitable. This dramatically expands the global capacity for mineralization-based storage.

Perhaps most significantly, the energy requirements have dropped. Direct air capture is energy-intensive because CO2 is present in the atmosphere at very low concentrations, roughly four hundred parts per million. Separating it from air requires moving enormous volumes of air through capture systems. The 2026 breakthrough reduces the energy cost of both the capture and the injection steps, bringing the overall cost per ton closer to levels where large-scale deployment becomes economically viable.

04The speed of carbon mineralization

The speed of mineralization is a critical factor because it determines how quickly captured carbon is permanently removed from the carbon cycle. In the CarbFix pilot, approximately ninety-five percent of injected CO2 was mineralized within two years. The 2026 breakthrough claims mineralization in a matter of weeks under optimized conditions, a dramatic improvement that reduces the risk window between injection and permanent storage.

Speed matters for verification. When CO2 is stored as a gas, monitoring must continue for decades to ensure it does not leak. When CO2 is mineralized, verification is simpler: once the carbonate has formed, it is stable and does not require ongoing monitoring. Faster mineralization means shorter verification periods and lower monitoring costs over the lifetime of a storage project.

The speed also affects the throughput of a storage site. If mineralization takes two years, the injection rate must be limited to avoid over-pressurizing the formation before the CO2 converts to solid. Faster mineralization allows higher injection rates, increasing the capacity of each site and reducing the number of sites needed to meet storage targets.

05Where this technology can be deployed

Basalt formations are found on every continent and form much of the ocean floor. Onshore basalt formations suitable for CO2 storage exist in Iceland, the United States, India, China, South Africa, and other countries. The global storage capacity in basalt has been estimated at hundreds of billions of tons of CO2, potentially enough to store decades of current emissions.

Iceland remains the leading deployment site, with its abundant basalt, renewable geothermal energy, and existing infrastructure from the CarbFix project. The United States has significant basalt formations in the Pacific Northwest, including the Columbia River Basalt Group, which has been the subject of storage feasibility studies. India has the Deccan Traps, one of the largest volcanic provinces on Earth.

The challenge is matching storage sites with capture sites. Direct air capture facilities can be built anywhere with sufficient energy, but the captured CO2 must then be transported to the storage site. Building capture facilities near basalt formations, powered by local renewable energy, is the most efficient configuration. This favors locations like Iceland, where geothermal energy and basalt coexist, but limits deployment in regions where the geology is not suitable.

06Cost comparison with other storage methods

Carbon capture and storage is a process by which carbon dioxide from sources like coal-fired power plants or directly from the atmosphere is captured, transported to a storage site, and deposited so that it will not enter the atmosphere. The cost of this process varies enormously depending on the capture source, transport distance, and storage method.

Mineralization in basalt has historically been more expensive per ton of CO2 than storage in depleted oil reservoirs or saline aquifers, because the injection process is more complex and the reaction requires specific conditions. However, when the full lifecycle cost is considered, including the cost of long-term monitoring and the risk of leakage from gas-phase storage, mineralization becomes more competitive. The 2026 breakthrough, by reducing the energy and infrastructure costs, narrows the gap further.

The current cost of direct air capture with mineralization storage is estimated at several hundred dollars per ton of CO2. While this is far above the price of carbon in most emissions trading systems, it is falling rapidly. The 2026 breakthrough represents a step toward the cost targets that would make large-scale deployment economically feasible, though significant further cost reductions are still needed.

07What scaling mineralization requires

Scaling direct air capture with mineralization storage to a level that matters for the global carbon budget requires enormous investment and infrastructure. To remove one billion tons of CO2 per year, a meaningful fraction of current emissions, would require thousands of capture facilities, each processing millions of tons of air annually, and an injection infrastructure comparable to the global oil pipeline network.

The energy requirement is the most significant constraint. Direct air capture is energy-intensive, and that energy must come from sources that do not themselves emit CO2. Geothermal energy, as used in Iceland, is ideal but limited in availability. Solar and wind power can be used but introduce intermittency challenges. The energy cost of capture must fall, or the price of carbon must rise, before the technology can scale to globally significant levels.

The regulatory and verification framework must also mature. Carbon removal credits based on mineralization need credible measurement, reporting, and verification standards to ensure that claims of permanent removal are accurate. The 2026 breakthrough, by demonstrating rapid and verifiable mineralization, strengthens the case for mineralization-based credits, but the market infrastructure for trading and verifying these credits is still in its early stages.