What are the typical power supply solutions for underwater robots?

Hello, when it comes to the energy source for underwater robots, this is a core issue that directly determines how far a robot can travel and how long it can operate. Simply put, it's like a mobile phone becoming a brick when its battery dies. Currently, there are several main solutions:

1. Dragging a "Pigtail" – Umbilical Cable Power Supply

This is the most common and reliable method. You can imagine it as a vacuum cleaner that's always plugged in. The robot drags a long cable behind it (which we call an "umbilical cable"), and this cable directly supplies power from a surface vessel or platform.

• Pros: Simple and robust, with virtually unlimited energy, allowing for operation as long as needed. Moreover, this cable can not only transmit power but also high-definition video and control signals, quickly and without delay.
• Cons: The robot's range of motion is restricted by the cable's length, preventing it from traveling far. In complex underwater environments, such as areas with many reefs or shipwrecks, this "pigtail" can easily get snagged or entangled, which can be problematic.

Therefore, this method is generally used for robots that do not require extensive movement, performing fixed-point operations or operating close to the mother vessel.

2. Self-contained "Power Bank" – Battery Power Supply

For robots that need to explore freely and over large areas (what we call Autonomous Underwater Vehicles, or AUVs), dragging a cable is definitely not an option. So, they carry their own power source, just like our mobile phones and laptops, using batteries.

• Pros: No cable constraints, allowing them to roam freely and go anywhere they want, offering great flexibility.
• Cons: Limited power! When the battery runs out, it has to return for recharging. This limits its operating time; after a few or a dozen hours, it needs to be recovered, recharged, and then redeployed. This back-and-forth process is both time-consuming and labor-intensive. Currently, lithium batteries are commonly used, similar to those in electric vehicles, offering higher energy density to allow robots to operate longer.

3. "Refueling" instead of "Recharging" – Fuel Cells

This is a more advanced solution, which can be seen as an "enhanced version" of the battery solution. It also carries its own energy, but instead of recharging, it generates electricity by consuming fuel (e.g., hydrogen and oxygen), much like a car refuels.

• Pros: Significantly higher energy density than conventional lithium batteries, allowing robots to stay underwater for dozens of days or even longer, greatly extending operating time.
• Cons: The technology is complex and very expensive, and fuel storage and refueling also require specialized equipment and technology. It is not yet widespread and is generally used for specific long-endurance scientific research or military missions.

4. "Underwater Charging Station" – Underwater Wireless Charging

To address the pain point of battery-powered robots needing to be recovered for recharging, scientists have devised a clever solution: building a "charging station" (underwater docking and charging station) on the seabed. When a robot runs low on power, it autonomously locates this station and "docks" with it, wirelessly charging itself like a mobile phone. At the same time, it can transmit collected data back to shore via a high-speed connection.

• Pros: Achieves truly long-term, unattended underwater operations. Robots can follow a work-charge-work cycle, eliminating the need for frequent recovery.
• Cons: Deploying and maintaining such a charging system underwater is extremely difficult and costly. It is currently still in the experimental and demonstration application stage, far from widespread adoption.

In summary, the most mainstream solutions currently are umbilical cables and batteries, which correspond to two different application scenarios: "working close to home" and "roaming freely," respectively. The other solutions represent future development directions, all aimed at enabling robots to operate more freely and for longer periods underwater.