Project Greenfuse: Coastal Enhanced Weathering of Olivine

Coastal Enhanced Weathering of Olivine (CEWO) is a proposed tool for countering ocean acidification and removing CO2 from the atmosphere. It involves spreading of crushed alkaline minerals, such as olivine, onto beaches and coastal shelves where waves and currents provide the grinding force necessary to enhance the dissolution. The resulting increase in pH and ocean alkalinity creates a driving force for the removal of CO2 from the atmosphere, increasing the concentration of dissolved ocean bicarbonate, which is a stable store of carbon for hundreds to thousands of years. For the Project Green Fuse, large-scale lab experiments are designed to improve upon knowledge obtained from bench-scale lab experiments by mimicking conditions which more closely resemble coastal environments. The first test involves weathering of olivine under the action of tidal currents in an 11-metre laboratory flume (see image) for a period of several months. The seawater is programmed to flow over the olivine-quartz gravel mixture in a tidal regime while monitoring the pH, temperature and electrical conductivity, with seawater samples extracted periodically for analysis of the total alkalinity and the composition of dissolved solids. The mechanics and kinetics of the olivine weathering are ascertained to better gauge how CEWO would perform in real coastal environments. Future experiments are planned to investigate olivine weathering in even larger laboratory flumes, under the action of waves rather than currents.