Session: 13-01: Carbon Capture & Cleaner Fossil Fuel Technologies

Paper Number: 130772

130772 - Techno-Economic Modeling of CO2 Hydrate Slurry Formation for Carbon Sequestration 

Abstract: 

Significant carbon sequestration capacity (up to 10 Gigatons/yr) will be needed by 2050 to limit the Earth’s temperature rise to < 1.5 ºC, while the current worldwide capacity is <50Mt/yr. One such technology for long-term sequestration of CO₂ is the deposition of CO₂ hydrates on the seabed, where the natural conditions provide a thermodynamically stable environment for hydrate formation. From a technical standpoint, the success of this concept requires rapid synthesis of CO₂ hydrate slurry, compacting slurry into plugs, sealing them (to prevent dissociation), and seabed disposal for long-term sequestration (> 1000 yrs). To bring such a technology to maturity, the need for a technical optimization of the CO₂ hydrate formation rates, along with a techno-economic analysis for its implementation at industrial scales would be imminent. This work focuses on the techno-economic modeling of hydrate slurry formation in a bubble column reactor.

 

Mechanical agitation and chemical promotion are often used for the rapid conversion of CO₂ into CO₂ hydrates. While chemical promotion can be environmentally harmful, mechanical agitation often requires immense energy. Bubble column reactors allow heat and mass transfer enhancement with minimal energy requirements. This work uses experimental results that report ultrafast hydrate formation rates (>6x the status quo) in a bubble column reactor. This is attained by using pure CO₂ and tap water in a small reactor using continuous gas flow at high flow rates, with the excess CO₂ to be recirculated. The rate of formation is quantified using hydrate dissociation and the resulting over-pressurization. The formation rats are studied for a range of pressure and temperature. These high formation rates are considered the basis for a techno-economic model of hydrate slurry formation, evaluating the CAPEX and OPEX for CO₂ sequestration in the form of hydrate slurry. The analysis targets a CO₂ sequestration rate of 1Mt/yr for a 30-year project, which is typical for an industrial plant. The effect of varying this scale in the range 1kton/yr to 10Mt/yr is also studied. The analysis also covers other key parameters like water requirement, energy requirement, sensitivity to electricity cost, etc. The cost-benefit of recirculating CO₂ and excess water for hydrate slurry formation is also discussed. The energy and cost requirements for operating the system at a range of thermodynamic conditions are studied. Overall, this study helps analyze the feasibility of the implementation of CO₂ hydrates-based carbon sequestration at different geological sites such as the Gulf of Mexico or the seabed at Antarctica.

Presenting Author: Awan Bhati University of Texas, Austin

Presenting Author Biography: Awan is a PhD student at the University of Texas at Austin. His thesis is focused on CO2 hydrates for carbon capture and sequestration (CCS) application. His background is in CCS, atomization, heat transfer enhancement, hydrogen, energy storage systems, and boiling.

Authors:

Awan Bhati University of Texas, Austin
Vaibhav Bahadur University of Texas, Austin