Enhanced rock weathering (ERW) is a carbon removal method that spreads crushed alkaline minerals on soil to trap CO2. The problem is that natural minerals dissolve too slowly to make a dent in atmospheric carbon. Researchers at Stanford have now created a synthetic mineral mixture called Monti that weathers much faster than basalt, the current standard feedstock. In bucket-sized soil simulations, Monti removed an average of 4.18 metric tons of CO2 per hectare over 42 weeks. Basalt showed no significant increase in dissolved inorganic carbon, and limestone removed only 0.49 tons. The startup Mafix plans to scale Monti by partnering with a cement manufacturer and running field trials with farmers. One open question is whether alkalinity will wash away before it can be measured in real fields. The mesocosm results are promising, but the next step is to confirm the same performance in actual agricultural conditions.
