Natural gas hydrate production and CO2 storage via clathrate hydrates: Challenges and opportunities

Abstract One of the most demanding environmental and economic challenges of this era is that of supplying the increasing global energy demand while reducing and neutralizing the CO 2 footprint. In this regard, the provision of a secure and diversified energy supply and the sequestration of CO 2 into geological formations are currently of great significance. However, the buoyant nature of CO 2 under the temperature and pressure conditions of typical geological sites leads to the risk of CO 2 leakage, and thus necessitates long-term monitoring. Therefore, the hydrate-based sequestration of CO 2 beneath oceanic sediments has become a desirable alternative to conventional geologic sequestration in some regions, with the potential to eliminate the risks of leaking CO 2 . Over the past decades, considerable progress has been made in the study of gas hydrates, including understanding their occurrence in nature, characterizing their behavior, and assessing their energy and exploitation potentials, along with the potential development of sustainable hydrate-based chemistry applications and technologies. Due to the significance and severity of plugged oil/gas flowlines, the early research was dominated by the inhibition of gas hydrates in order to provide flow assurance in pipelines. However, the discovery of vast natural gas hydrate resources has shifted scientific attention towards the possibility of storing CO 2 as a hydrate, and developing applications such as CO 2 capture and transportation, gas separation, cold storage, natural gas solidification, and CH 4 -CO 2 hydrate replacement. Hence, the present review examines the fundamental properties of gas hydrates, including their natural occurrence and distribution in geological sediments, along with their thermodynamic and kinetic behaviors with respect to the effects of promoting and inhibiting additives. In addition, natural gas hydrate (NGH) production methods and field-scale trials are reviewed. Furthermore, various concepts and experimental investigations pertaining to hydrate-based CO 2 sequestration pathways are reviewed in the final section, including sequestration in the deep ocean, sub-permafrost regions, and marine sediments, as well as the CH 4 -CO 2 hydrate replacement technique. Therefore, CO 2 hydrate storage in suitable depleted oil and gas fields has the potential to reduce infrastructure costs, with CH 4 -CO 2 hydrate replacement potentially providing additional economic incentives. However, long-term field trials in marine sediments with different compositions are required to assess the CO 2 storage potential of hydrate reservoirs, and the effectiveness of CH 4 -CO 2 hydrate replacement technique.