Carbon Dioxide Sequestration in the Staten Island Serpentinite

The Intergovernmental Panel on Climate Change has suggested carbon dioxide capture and storage (CCS) as a method for mitigating climate change resulting from anthropogenic greenhouse gas emissions. The Staten Island Serpentinite has potential for permanent carbon storage via in situ mineral carbonation. This study proposes to dissolve CO₂ sourced from the Fresh Kills Park landfill gas processing plant into groundwater pumped from a saline aquifer below Staten Island. This CO₂-brine solution would be pumped back into the aquifer at a depth of 500m, where the partial pressure of CO₂ and temperature were calculated to be 50 bars and 40^°C, respectively. Assuming a grain size of 7mm, this study estimated a carbonation rate of 1.04x10⁹ tons CO₂ yr^-1 for the formation as a whole. This was shown to greatly surpass the CO₂ emissions from the landfill gas processing plant. This study also measured prior natural carbonation, which is an important factor in storage capacity. Carbon was found to comprise <0.1% of the serpentinite matrix, and ~10% of carbonate veins, indicating that veins are nearly pure carbonate and that the rest of the rock contains ample metal cations available for carbonation reactions. The natural rate of mineral carbonation was gauged by radiocarbon dating carbonate veins within the serpentine matrix. Two younger ages of 1,270±25 yr and 3,420±25 yr indicate that the Serpentinite is actively carbonating, while three older ages of ~40,000 years are near the upper end of ¹⁴C age resolution, and could be the result of minor amounts of solution and redeposition rather than the age of initial formation of carbonate. If a CCS project proves feasible, it may serve as a model for innovative urban CCS and waste management initiatives.