CO2 storage in marine sediments in form of hydrate: Thermodynamic evolution, time required and energy consumption

This research deepens the storage of carbon dioxide in marine sediments, under form of solid clathrate hydrates. CO 2 hydrates were produced in a small-scale reactor, where a marine porous sediment was previously reproduced. The formation of hydrates was divided into its main steps, respectively induction period, reaction initiation, hydrate growth within the hydrate stability zone (HSZ) and hydrate growth in correspondence of the phase boundary conditions. For each step and for the whole formation process, the corresponding pressure/temperature conditions and the time required were measured. Moreover, the energy spent for gas cooling and compression was calculated and the overall energy required per mass unit of CO 2 stored, was defined accordingly. Based on the results produced, 11.82–13.52 kJ needed for gas cooling and 6.26–6.72 kJ for its compression. The total energy spent, per unit of CO 2 captured, ranged within 87.97–91.2 kJ/mol. • The study deals with CO 2 storage in marine seafloors in form of hydrate. • To capture 0.198–0.227 mol of CO 2 , 18.08–20.21 kJ were spent for gas pretreatment. • The energy spent per unit of mass of CO 2 varied from 91.32 to 87.97 kJ/mol. • Except the induction period, the production time remained constant in Tests 1–5. • The energy consumption gradually decreased, denoting the role of “memory effect”.