POTENTIAL FOR DESCENDING METEORIC WATER RECHARGE IN HYDROTHERMAL SYSTEMS AS A PATHWAY FOR CARBON DIOXIDE SEQUESTRATION
Keywords:CO2 Sequestration, Geological Storage, Saline Aquifers, Carbonate Mineralization, Geothermal Systems
The storage of carbon dioxide in secure underground sites has been identified as an important contributor to preventing climate change impacts of excessive CO2 in the atmosphere. Significant quantities of carbon dioxide must be collected and stored for this technology to make the required contribution to climate change abatement. The carbon dioxide can be stored as a gas, supercritical fluid or a solid by mineralization. Most attention has been on reservoirs which are depleted in oil or gas or in saline aquifers more generally. Trapping gas or supercritical fluid requires a setting similar to the natural trapping of gases in sub-surface sedimentary rock reservoirs. The most advanced high-volume projects focus on the trapping of supercritical fluids. Pumping carbon dioxide into basalt host rocks to promote carbonate mineralization is also being undertaken. In this paper another environment in which CO2 is naturally introduced into geological materials and stored below ground is reviewed. The environment is natural hydrothermal systems which are commonly found around magmatically active locations. In these areas it is common for the cool near-surface (meteoric) water to descend as a replacement (recharge) of the warm or hot magmatic water in the hydrothermal-magmatic system. The descending CO2 can react with existing rocks and minerals to form carbonates of calcium and other cations. It is proposed that introduction of CO2 into naturally descending meteoric water recharge in hydrothermal systems may be a mechanism for CO2 sequestration by mineral trapping. Further investigation of this process and its potential is proposed.