Deep-Sea Thrusters: The Technical Game Behind Energy Endurance

In the dark deep-sea environment, energy is the core bottleneck restricting the scope of exploration. As the "power output terminal," the endurance of deep-sea thrusters directly determines the operating time, detection radius, and mission completion of submersibles. Unlike land-based equipment that can be recharged at any time, the energy supply of deep-sea equipment must achieve "efficient storage, stable output, and precise distribution" within a limited space. Every technical choice embodies engineers' pursuit of extreme energy utilization efficiency, and this "game" centered on energy has become the key thread driving the technological development of deep-sea thrusters.

Battery energy storage is currently the most mainstream energy source for deep-sea thrusters, with its core challenge lying in the "balance between energy density and pressure-resistant safety." Lithium batteries used in deep-sea thrusters require special modifications: on one hand, high-energy-density ternary lithium batteries or lithium iron phosphate batteries are adopted to store more electricity in a limited volume — for example, the special lithium batteries equipped on China's "Fendouzhe" (Striver) submersible have an energy density 1.5 times that of ordinary power batteries, supporting it to operate for several hours at the 10,000-meter seabed; on the other hand, the battery compartment must have extremely strong pressure-resistant and sealing performance. Through a titanium alloy shell and multi-layer insulation protection, seawater infiltration (which could cause short circuits) is prevented. At the same time, a passive heat dissipation design is used to avoid heat accumulation generated during battery operation, which might lead to thermal runaway. To improve endurance, engineers also adopt "energy recovery" technology: when the submersible dives or decelerates, kinetic energy is converted into electrical energy to recharge the battery, realizing the cyclic utilization of energy.

For long-duration and long-distance deep-sea missions, single battery energy storage can hardly meet the demand, and the "hybrid power system" has become a breakthrough direction. The current mainstream hybrid solution is the "battery + fuel cell" combination: the battery is responsible for providing instantaneous high thrust to meet the high-intensity power needs of the thruster, such as acceleration and steering; the fuel cell continuously generates electricity through the chemical reaction between hydrogen and oxygen to recharge the battery and extend the endurance time. Under this mode, the energy supply of the thruster is more flexible — for instance, a deep-sea cruising robot can rely on fuel cells to operate continuously for days or even weeks, while when facing complex terrain that requires flexible maneuvering, the battery can output high power instantly to ensure precise movements. However, the deep-sea adaptation of fuel cells still faces challenges: hydrogen storage requires a high-pressure sealed cabin, and oxygen needs to be extracted from seawater or carried in advance, making system complexity and weight control the key technical issues.

In addition to optimizing energy supply, reducing the thruster's own energy consumption is also a core path to improve endurance. Starting from "reducing energy loss," engineers have carried out all-round technological innovations: in the power transmission link, a direct-drive motor design is adopted, eliminating intermediate transmission components such as gearboxes, which reduces energy loss by more than 30%; the propeller adopts a bionic fluid dynamics design, imitating the curved structure of whale fins to reduce water flow resistance and improve propulsion efficiency; the control system introduces an intelligent energy management algorithm to dynamically allocate electrical energy according to mission needs — reducing thrust output to save energy during scientific sampling, and automatically increasing power to ensure safety during emergency avoidance. These detailed optimizations seem minor, but they can accumulate significant endurance improvements during long-term operations, enabling the thruster to achieve "maximum efficiency" with limited energy.

Energy supply in extreme environments has always been a technical pain point for deep-sea thrusters. From single batteries to hybrid power, and from passive energy conservation to intelligent management, every technological breakthrough narrows the gap between "energy supply" and "mission requirements." In the future, with the maturity of new technologies such as solid-state batteries and deep-sea thermoelectric power generation, deep-sea thrusters may realize the possibility of "unlimited endurance" — relying on the temperature difference between the surface and the bottom of the deep sea to generate electricity continuously, or achieving self-sufficiency in energy through high-efficiency energy storage technology. This game centered on energy not only promotes the iterative upgrading of thruster technology but also will enable humanity to go further and longer on the road of deep-sea exploration.