Enhanced weathering of mafic rocks in tropical Colombia

The tropics have the potential to capture large amounts of CO2 through enhanced weathering of mafic rocks. This negative emissions technology can be articulated with the needs of the agricultural sector, in particular the large irrigated tropical cropland in the tropics. High-yield agricultural soils in the tropics are acidic. Their acidity is traditionally controlled with lime, which in turn emits  CO2. Crushed mafic rocks can be used instead of lime, with the added benefit of not only avoiding the lime emissions, but also capturing CO2. In tropical Colombia, there are extensive plantations of African oil palm, sugar cane, rice, banana, and corn. Nearby, there are large open-cast mining operations that produce massive volumes of mafic and ultramafic rocks as waste product. We are characterizing mafic and ultramafic rocks closest to the potential application sites, as well as the products of their weathering under natural conditions. We are also conducting field experiments with natural soils from areas of active afforestation, as well as in soils degraded by cattle ranching. Both were previously covered by rain forests. In these experiments we are evaluating the reaction rates and efficiencies of mafic and ultramafic rocks under tropical conditions in natural soils. We aim to establish the technical and scientific basis for a process by which the forestry, mining, agricultural, and energy industries in the tropics can reduce their operational carbon footprint, and eventually offer carbon capture bonds in the international market.