Artificial gills for ocean gliders
Hereon researchers develop an energy system for autonomous underwater vehicles
Autonomous underwater robots, such as ocean gliders, are essential tools in marine research. Most of these systems are powered by lithium batteries, which come with significant drawbacks. To address these, scientists at the Helmholtz-Zentrum Hereon have developed a new energy system. With hydrogen as an energy source, it is significantly more sustainable than lithium batteries and enables a greater range for ocean gliders. The unique feature: employing membrane technology, it extracts oxygen from seawater—much like a fish’s gills.
Ocean gliders can autonomously navigate the ocean for several weeks. Their sensors measure parameters like temperature, pressure, salinity, oxygen concentration, and currents. Capable of diving to depths of up to 1,000 metres, they facilitate measurements that are challenging to achieve with research vessels. Additionally, gliders can be operated at a much lower costs than research vessels. However, lithium batteries pose challenges for research teams. Classified as hazardous materials, they can only be transported under strict safety regulations, complicating logistics and increasing project costs.
Dr Lucas Merckelbach and Dr Prokopios Georgopanos from the Helmholtz-Zentrum Hereon have developed an alternative. Instead of using batteries, they propose powering gliders with a fuel cell that generates electricity from hydrogen and oxygen. A glider can then be filled up with hydrogen at the deployment site. A container with metal hydrides serves as a safe and efficient storage medium. These hydrides store hydrogen by bonding hydrogen to the metal hydrides at the atomic level. Oxygen, on the other hand, is not stored but extracted directly from seawater. “Nature is a great source of inspiration for us”, says Dr Lucas Merckelbach. He works at the Institute of Coastal Ocean Dynamics and uses ocean gliders in his own research. (Source: Hereon Press Release)
Read the complete Hereon Press Release:
==> Artificial gills for ocean gliders
Merckelbach, L., & Georgopanos, P. (2025): A Fuel Cell Power Supply System Equipped with Artificial Gill Membranes for Underwater Applications. Adv. Sci. 2025, 2410358, doi:10.1002/advs.202410358
Abstract:
This work proposes a fuel cell power supply system for underwater applications (e.g., autonomous underwater vehicles), where artificial gills, based on a polymer membrane, harvest the required oxygen from the ambient water. In this system, a circulating air-flow continuously supplies a proton exchange membrane fuel cell with oxygen, which is replenished using a polymer membrane. The membrane serves as the interface between the circulating air-flow and the ambient water, preventing water flux while allowing an oxygen flux across the membrane, driven by a partial oxygen pressure gradient. To demonstrate the feasibility of this concept, a prototype system was built based on guidelines derived from a mathematical model that was developed to describe the oxygen transfer process. A computational fluid dynamics model is developed and validated against the measurements from the prototype, resulting in a digital twin. The analysis indicates that the proposed power supply system has the potential to be superior to any battery-based solution currently available.
