Unlocking theocean's potential: enhancing carbon capture throughinnovative replacement ofmethane hydrate byCO2

Abstract

This research explores the innovative method of enhancing carbon capture by substituting methane hydrate with CO2 in ocean sediments, a promising strategy for mitigating greenhouse gas emissions. Methane hydrates, ice-like compounds where methane is trapped within a water molecule cage, are abundant in marine sediments and offer a potential target for CO2 sequestration. The objective of this mission is to establish one kinetic model in non-equilibrium state based on the physical mechanism. It aims at quantitatively estimating the oceanic carbon dioxide hydrate formation rate through the dissociation of methane hydrate with CO2 injection in the solid phase. Utilizing this kinetic replacement model, this study also examines the efficiency of this substitution process, where CO2 replaces methane in solid methane hydrate structures, potentially locking away CO2 and recovering methane as an energy resource. The methodology includes numerical modeling to simulate the replacement dynamics and an experimental approach using a high-pressure reactor system for real-time gas composition measurement during the substitution process. Data analysis reveals that CO2 can effectively replace methane in hydrates, and methane gradually diffuses from deep hydrate cage due to difference of concentration. The replacement efficiency is significantly influenced by the diffusivity of guest molecules within the hydrate and experimental conditions. The comparison of numerical and experimental flux validates the kinetic surface model. This works also proofs a viable dual benefit of enhancing methane recovery while sequestering CO2, suggesting potential for scaling up this technology for environmental and energy applications. Future work will focus on optimizing the substitution process and assessing its environmental impact and economic viability.