Increasing concentration of CO 2 in the atmosphere poses a threat to the global climate. One promising method for reducing atmospheric CO 2 is a repeated enhanced weathering process. Enhanced weathering is a process where a natural reaction between CO 2 gas and minerals rich in magnesium and/or calcium is accelerated to quickly form a solid carbonate. The cycle can be repeated by separating the CO 2 from the carbonate by heating it up, extracting the pure CO 2 , and exposing the reactive minerals to the air again. The technology we propose here combines innovations in enhanced weathering alongside an engineered system that passively exposes these reactive minerals to the air. It has the potential to significantly reduce the cost of permanent, high quality carbon removal, and the resulting pure CO 2 can be permanently stored in geological formations or sold for use in durable goods like cement or building materials. This project aims to validate key parameters that have already been established at lab scale, build a proof-of-concept of the engineered âpassive air contactorâ, and perform an economic and geographic assessment of the process to find ideal locations to implement the process. In addition to low costs, the process is limited in land requirements, can be located anywhere, is highly verifiable and monitorable, is permanent, and limits the need for mining and extraction. Bringing this technology and process to market has the potential to remove 1 gigaton of CO 2 by 2035, at a cost of $50/tCO
