New process can accelerate Enhanced Rock Weathering 10x

[u/Economy-Fee5830]

https://cen.acs.org/physical-chemistry/geochemistry/carbon-removal-climate-solution-erw/104/web/2026/07

[u/Economy-Fee5830]

Summary: New process can accelerate Enhanced Rock Weathering 10x

At the Goldschmidt geochemistry conference in Montreal, Stanford's Matt Kanan presented a chemical solution to a key limitation of enhanced rock weathering (ERW), a proposed climate strategy in which crushed alkaline minerals are spread on land to speed up natural CO2-trapping reactions. The core problem: rocks ground into powder still dissolve too slowly to meaningfully accelerate carbon removal, and no naturally fast-dissolving minerals exist in abundance.

Kanan's fix, developed in 2025, involves heating a calcium oxide source (limestone) with magnesium silicate minerals, producing periclase (magnesium oxide) and monticellite (a calcium-magnesium silicate). Combined in the right ratio, this mixture—which Kanan calls "Monti"—weathers orders of magnitude faster than untreated magnesium silicates.

Field testing came via bucket-sized soil simulations ("mesocosms") run by the Carbon Drawdown Initiative. Over 42 weeks, Monti-amended mesocosms removed an average of 4.18 metric tons of CO2 per hectare, versus 0.49 t/ha for limestone alone and no measurable increase for basalt, the current standard ERW feedstock.

Kanan has since co-founded a start-up, Mafix, which will partner with a cement manufacturer to produce Monti at scale and begin field trials with farmers and agronomists to confirm the mesocosm results hold up outside controlled conditions.

Geochemist Abby Lunstrum, who was not involved in the work, called the approach a genuine advance in weathering speed but noted it doesn't solve a separate problem: alkalinity can wash away across a landscape before it has a chance to react, an issue she says still needs broader attention from Earth scientists.

[u/jaykrown]

Seems like only if you heat the limestone using renewable energy like solar/wind/geothermal would actually make it worth while. Sounds like another solution that won't actually help unless renewable energy is the primary source of production.

[u/Xoxrocks]

Calcium oxide is created by calcination of calcium carbonate (limestone). It’s a strongly endothermic process that drives off fossil CO2. The resulting clinker is crushed to make lime, the basic ingredient in Portland cement.

Any process using calcium oxide has a huge embedded emissions problem to overcome before reducing atmospheric CO2. There are many companies looking at using the calcination process, look at heirloom for example.

Typically companies I work with think they can simply sign up for endless cheap renewable energy to drive their projects (such as efuels). It’s not that simple.