Laboratory demonstration of the stability of CO2 hydrates in deep-oceanic sediments

Abstract

Naturally occurring methane (CH4) hydrates in oceanic sediments have been stable for millions of years. As a natural analog, is it possible to store carbon dioxide (CO2) in the form of hydrates in oceanic sediments for long durations? This is a key question that has had a minimal experimental investigation. Despite the extensive research conducted on CO2 hydrates in carbon capture, CO2-CH4 exchange, and promoter/inhibitor effects on CO2 hydrate formation kinetics, fundamental understanding of and demonstration of CO2 hydrate stability under oceanic sediment conditions remains elusive. In this work, an experimental study has been conducted that provides conclusive insights into the stability of the CO2 hydrates across oceanic sediments. By conducting an experimental study mimicking the oceanic sediment conditions inside a laboratory-scale high-pressure reactor system, we observed that CO2 hydrates formed at reactor walls and inside the sand bed were stable for the entire test period (one month), after which they were intentionally dissociated. This study offers scientific evidence and support for sequestering CO2 in the form of hydrates across oceanic sediments for extended durations.