Role of Carbon in Environmentally “Benign” Sequestration of CO2

  • Nazim Muradov, Florida Solar Energy Center, University of Central Florida, United States
  • Fossil-based power generation coupled with CO2 sequestration is considered a prospective decarbonization strategy. However, the key risk factor associated with the geologic or ocean CO2 sequestration stems from uncertain long-term ecological consequences of this approach. To avoid a negative environmental impact of CO2 sequestration, recently, there have been new developments referred to in the literature as environmentally “benign” CO2 sequestration (EBS) (e.g., via mineral carbonation using limestone, olivine, etc). The objective of this work is to assess the feasibility of a novel approach to EBS that involves stabilization of liquid CO2 (L-CO2) droplets in water using carbon particulates. Due to a dual functionality of carbon particles (i.e., hydrophobic-hydrophilic) they tend to form a film of nano- or micron-sized carbon particles at the L-CO2-water interface, thus stabilizing the emulsion. L-CO2 droplets are protected by a double “skin” comprising two solid phase layers (i.e., CO2-hydrate and carbon), which will prevent (or substantially slow down) CO2 interaction with surrounding water (affecting its pH). Most importantly, due to an increased density of the carbon-laden CO2 droplets they could be injected at depths as low as 500 m (compared to 3000 m without carbon), which would significantly lower the cost of sequestration by reducing the length of pipelines and decreasing energy consumption. The preliminary proof-of-the-concept experiments conducted at FSEC demonstrated that micron-sized carbon particles stabilized oil-droplets (modeling L-CO2) and the resulting carbon-oil-water system was stable for over a year. Further research is needed to prove technical feasibility of this concept using real L-CO2 droplets.