Bapon (SHM) Fakhruddin, PhD

The oceans currently absorb almost 1/3 of anthropogenic carbon dioxide emissions. By dissolving just one gigatonne of ground olivine mineral per year in shallow seas, atmospheric CO2 could be reduced by 10 parts per million and lower Earth’s temperature by 0.06°C by 2100. This is based on the high emissions scenario modelled where atmospheric CO2 reaches 1200 ppm. While we must cut emissions drastically, green sand deployment could help compensate for demanding decarbonising sectors like steel and aviation.

The process works by enhancing natural rock weathering. When olivine reacts with seawater, it forms bicarbonate, raising alkalinity. This allows more carbon dioxide to dissolve. Spreading green sand across shallow shelves rather than the open ocean prevents it from sinking into the depths. Currents then redistribute the dissolved CO2. Over half of the atmospheric absorption occurs off the shelves after dispersion.

Regional case studies show significant potential for shallow and warm seas to facilitate green sand weathering and carbon dioxide intake. The Yellow Sea, Gulf of Mexico, Persian Gulf and waters around Indonesia and Malaysia are prime targets. However, possible ecological impacts must be considered. A 2023 study found olivine sand may negatively impact zooplankton, disrupting marine food chains. Additionally, the local effects of increased alkalinity on organisms near discharge sites requires further research.

While more data is needed, this innovative climate solution using green sand shows promise for cost-effectively removing carbon dioxide at scale. We need to prioritize research into deployment methods and environmental impacts so this technology can be responsibly developed. If realized, it would greatly aid the mission of carbon neutrality and climate stability.

https://www.technologyreview.com/2020/06/22/1004218/how-green-sand-could-capture-billions-of-tons-of-carbon-dioxide/