To demystify this concept let us break it down into the basics: Enhanced weathering (EW) is the process of grinding silica rich rock material to produce a fine powder which is then spread on a land or ocean surface. EW is so interesting because it is a major natural carbon storage process that locks up CO2 in the form of carbonates, thus storing them for an extremely long time. It is called enhanced, because through the human intervention of grinding and spreading the rock, the natural weathering process happens a lot faster. As the process is 100% nature based, there are low risks and no serious side effects.
Silica rich materials like basalt and olivine rocks are the most promising minerals in terms of carbon removal potential. They are available worldwide and can be pulverized using simple and proven milling technology. Another very interesting way to locally source rock powder may be the recycling of construction residues and concrete structures. However, this is a current field of research and discussion.
Due to the necessary pulverization of the rock, access to renewable energy sources as well as proximity to mines and quarries are key for a viable use case of EW. Even though suitable rock may not be as abundant and cheap as biomass, we identified EW as an important part of our solution based on two reasons: One, carbon captured through enhanced weathering processes is very long term and resilient. Two, biochar alone is an insufficient soil amendment. It needs mineral fertilization to really benefit the soil. Through a mix with rock powder we achieve a nutritious soil amendment that boosts Afforestation & Agroforestry efforts on our land.
Here are some studies we recommend for a deep dive:
de Oliveira Garcia, Wagner, et al. „Impacts of enhanced weathering on biomass production for negative emission technologies and soil hydrology.“ Biogeosciences 17.7 (2020): 2107-2133.
Renforth, Phil, and James S. Campbell. „The role of soils in the regulation of ocean acidification.“ Philosophical Transactions of the Royal Society B 376.1834 (2021): 20200174.
Webb, Romany. „The law of enhanced weathering for carbon dioxide removal.“ Sabin Center for Climate Change Law, Columbia Law School (2020).