What is Enhanced Mineralization?

Enhanced mineralization, also known as enhanced weathering or accelerated weathering, accelerates the natural processes by which various minerals absorb carbon dioxide (CO₂) from the atmosphere. This natural process, called weathering, currently converts about one billion tons each year of atmospheric CO₂ into minerals, providing reliable, long-term storage. Enhancing or speeding up this weathering process would begin with the mining and processing of specific kinds of rock, such as olivine or basalt, or with waste materials from mining, steelmaking, or other industries. One prominent proposal for implementation would involve grinding basalt into powder and spreading the powder over soils, where it would react with CO₂ in the air to form stable carbonate minerals. Other proposals involve exposing the powdered rock to streams of pure CO₂ from power plants or direct air capture facilities or using it for a related oceans-based approach to carbon removal known as ocean alkalinization.

Co-Benefits and Concerns

• Improved soil quality: depending on the type of rock used, spreading powdered rock over soils could improve soil quality by adding nutrients.
• Concerns associated with mining: most enhanced mineralization requires extensive mining and processing of raw materials, which raises a range of local environmental and health concerns
• Soil and groundwater contamination: depending on the context and the type of rock used, heavy metals could leach from powdered rock into soils or groundwater

Potential Scale and Costs

The long-term potential for enhanced mineralization is very large, both in terms of annual carbon removal and cumulative carbon sequestration. A recent expert assessment estimates that enhanced mineralization could be scaled up to capture 2–4 billion metric tons of CO₂ (GtCO₂) per year by 2050, with rates of more than 20 GtCO₂ per year theoretically possible by 2100. Estimates of the cumulative potential in this century range from 100 GtCO₂ to 367 GtCO₂. Cost estimates vary widely, from less than $50 per ton of CO₂ sequestered to more than $200 per ton.

Technological Readiness

The basic chemistry of enhanced mineralization is well understood, and the technology to mine, grind, and disperse rock is widely available. Research on enhanced mineralization as a form of carbon removal, however, remains in comparatively early stages, with much more work to be done to evaluate its efficacy and social and environmental sustainability. The first major field trials, looking at on-site weathering of mining wastes, are under way in Canada.

Governance Considerations

• Monitoring, verification, and reporting of sequestration: processes, standards, and technologies need to be developed to reliably measure carbon sequestration.
• Encouraging adoption: incentives would be needed to encourage widespread adoption in a range of different contexts.
• Ensuring environmental and social sustainability: policies are needed to ensure the environmental and social sustainability of mining, processing, transport, and application of minerals across complex supply chains.
• For cross-cutting considerations, see our What Is Carbon Removal? fact sheet.

Last updated June 24, 2020