Exploring the Untapped Potential in Enhanced Rock Weathering: The Magnesium Advantage

You may be familiar with enhanced rock weathering (ERW) as a promising method for carbon dioxide removal. Much of the current discussion and deployment – perhaps around 95% of ERW efforts – understandably focuses on calcium-based minerals, which have been more readily adopted. However, a deeper look into the geochemistry reveals that magnesium-rich minerals like olivine possess inherent advantages in efficiency, which can translate to lower operational costs and a higher density of carbon removal per tonne of rock applied.

Historically, these highly efficient magnesium minerals have often been sidelined due to concerns about their naturally occurring trace nickel content, particularly when considering application on agricultural lands. With innovative approaches, such as Metalplant’s integration of phytomining to recover nickel and a focus on operating on existing nickel-bearing soils, the path is clearing to re-evaluate and harness the significant CO₂ removal potential of fast-weathering, magnesium-rich minerals like olivine.

This white paper, “The Overlooked Magnesium Advantage in Enhanced Rock Weathering,” delves into the scientific reasons why magnesium-based feedstocks offer distinct benefits. After reading, the unique advantages of magnesium will no longer be overlooked.

Inside, you’ll discover detailed explanations of why magnesium-rich silicates are often superior, including:

• Superior Resistance to Premature Carbonate Formation: Learn how magnesium’s strong bond with water (its hydration shell) creates a significant kinetic barrier—requiring about 330 kJ/mol more energy to overcome than for calcium—preventing it from easily forming solid carbonate minerals in typical soil conditions. This ensures the captured carbon (as dissolved bicarbonate) remains mobile.

• Enhanced Permanence and Mobility of Sequestered Carbon: Unlike calcium, which can precipitate as calcium carbonate in soils (potentially re-releasing some CO₂ and immobilizing alkalinity locally), magnesium keeps the bicarbonate alkalinity dissolved and transportable through waterways to the ocean for durable, long-term storage.

• More Reliable Ocean Alkalinity Enhancement: Understand how magnesium’s much longer residence time in the ocean and its resistance to forming marine carbonates contribute more effectively and persistently to increasing the ocean’s carbon storage capacity and buffering against acidification.

• Greater CO₂ Removal Efficiency Per Tonne: Explore the data (including findings from lifecycle analyses like Breunig et al., 2024) showing that magnesium-rich minerals can sequester significantly more CO₂ per tonne of rock (e.g., olivine achieving ~760 kg net CO₂/tonne) compared to many calcium-based alternatives (125-160 kg net CO₂/tonne).

• Reduced Logistical and Economic Burdens: See how the higher efficiency per tonne translates directly into lower requirements for mining, grinding, transportation, and application, making ERW projects potentially more cost-effective and scalable.

• Simplified Monitoring and Verification: Discover why the tendency of magnesium to remain in solution can lead to more straightforward and reliable methods for monitoring carbon removal and verifying the transport of alkalinity.

• Benefits for Soil Processes: Learn how, by resisting extensive precipitation, magnesium can help maintain soil pore connectivity and hydraulic conductivity, supporting healthy soil functions (when applied with consideration for overall soil chemistry).

Gain a comprehensive understanding of the fundamental geochemistry that makes magnesium-rich minerals a highly promising, and arguably superior, option for scalable and effective carbon dioxide removal.

Download the full white paper below to explore the science in detail.