Atmospheric CO2 Removal by Enhanced Weathering of Mine Tailings Through Engineered Systems”, with Prof. Aidong Yang

Limiting global warming to the target of 1.5 ^◦C requires carbon dioxide removal (CDR) from the atmosphere of 100–1000 GtCO₂ this century. Among the CDR methods that can have been considered to date, enhanced weathering (EW) of carbonate or silicate minerals aims at accelerating the natural weathering process to draw down CO₂ from the atmosphere through chemical reactions between minerals, CO₂ and water. EW can be implemented by spreading crushed minerals in specific natural environments such as on the soil or in coastal areas. Compared to such “natural” deployments, options in which mineral particles are weathered in engineered reactors, where conditions are more controlled, could lead to benefits such as higher CDR rates and fewer unpredictable interactions with the natural environment. However, these benefits tend to be accompanied by greater energy and water consumption and other costs, which need to be quantified to assess the potential of such schemes. This talk discusses our recent work on EW of waste mineral materials - mine tailings in particular - using engineered systems, as part of the GGREW project funded by the Greenhouse Gas Removal Programme of NERC, UK. A review is first presented of the global availability and CDR potential of key types of mine tailings, estimated based on their chemical compositions and the weathering kinetics data. Resource requirements including particularly energy and land area are then assessed using mathematical models of several reactor designs. The overall technical, economic and environmental implications of the engineered EW schemes will be discussed within the context of global CDR requirements.