The high temperatures of sea-floor hydrothermal vents make them good targets for the exploitation of thermal energy. Taking advantage of this prospect, this study developed a thermoelectric converter that harvests thermal energy from hydrothermal fluids through a heat pipe and converts heat to electrical energy with thermoelectric generators. A power management system that enables the thermoelectric converter to continuously power a data logger and a light-emitting diode lamp was also proposed. The thermoelectric converter was field tested at a deep-sea hydrothermal vent with a depth of 2765 m at the Dragon Flag Field along the Southwest Indian Ridge. With the use of the thermal gradient between hydrothermal fluids and seawater, the thermoelectric converter obtained a sustained power of 2.6–3.9 W during the field test. Our results demonstrate that the thermal energy of hydrothermal fluids can be an alternative renewable power source for seabed observation equipment that requires watt-level power.
