Objective There are abundant methane hydrate resources in the South China Sea. The depressurization method is one of the most commonly used extraction techniques at present. However, as the endothermic decomposition of methane hydrate proceeds, problems such as wellbore freezing, secondary hydrate formation, and blockage occur, resulting in unsatisfactory gas production.

Method This study innovatively proposed a coupled mining system combining solar energy, seawater desalination, flue gas waste heat, and CO₂ displacement. CO₂ (the main component of flue gas) was stored in the form of hydrates on the seabed to displace and exploit methane hydrates. The waste heat from flue gas was used to heat the concentrated seawater produced by solar seawater desalination and then transported to the hydrate layer to achieve thermodynamic inhibition of hydrate reformation using high-temperature concentrated brine, thereby providing power for the continuous decomposition of methane hydrates.

Result Based on a case study of the methane hydrate reservoir at Station W19 in the Shenhu area of the South China Sea, compared with the traditional heat injection extraction method, the carbon capture amount in the process of extracting methane hydrates with the combined driving method is 1.16×10⁷ kg/d, and the energy consumption is saved by approximately 4.81×10⁵ kg/d of standard coal. The calculations indicate that the heat supplied by the concentrated brine for thermodynamic inhibition accounts for 57.66%, while the contribution from flue gas waste heat and CO₂ displacement accounts for 42.34%.

Conclusion Based on the analysis, the proposed joint energy supply method provides a novel pathway for the commercialized and sustainable exploitation of natural gas hydrates.