Abstract
Ocean thermal energy (OTE) and salinity gradient energy (SGE) systems face critical limitations in energy density and operational continuity due to fragmented exploitation of oceanic energy gradients. Phase Change Material (PCM) equipped thermal underwater gliders, through buoyancy regulation, enable the coupled conversion of thermal energy, pressure energy, and salinity gradient energy, along with an elevation in energy grade. This approach shows promise as a breakthrough technology for synergistic OTE-SGE exploitation. However, current research on OTE, SGE, and thermal underwater gliders remains fragmented and independent: OTE studies focus primarily on enhancing thermal efficiency under limited temperature differentials; SGE research concentrates on developing high-efficiency ion-exchange membranes for salinity gradient conversion; while thermal underwater gliders' energy output is still confined to propulsion functions. To date, no systematic framework integrating these technologies has emerged. The proposed system operates as a dynamic ‘energy glider’: descending via PCM solidification to concentrate brine under hydrostatic pressure, and converting amplified salt differentials into electricity through reverse electrodialysis (RED). This integration bypasses traditional pumps and turbines, offering a scalable solution for offshore energy autonomy.