Autonomous underwater drone with fuel cell stays underwater for over 2000 km

Canadian company Cellula Robotics, specializing in autonomous underwater vehicles (AUVs), has completed a total distance of 2023 km fully submerged with its autonomous underwater vehicle Envoy. The AUV was powered by a hydrogen fuel cell that produced electricity for its electric drive.

The mission of the approximately 8.5 m long and 2.7 t heavy Envoy underwater drone, which has a displacement of 3.7 t at a diameter of about one meter, lasted a total of 385 hours. The dive depth of the AUV is up to 6000 m, with an operational dive depth of about 2000 m.

The drone is equipped with an electric drive that draws power from lithium-ion batteries. These are recharged during the journey by a hydrogen fuel cell system from Infinity Fuel Cell and Hydrogen. The company produces fuel cell and electrolysis systems for aerospace, as well as for underwater and defense applications.

Operational duration of more than two weeks

The fuel cell system, with its tanks for hydrogen and oxygen, is designed to supply power for approximately 370 hours (15.4 days). However, during the test drive, the system lasted a little longer at 385 hours. Envoy slightly exceeded its maximum range of 2000 km with 2023 km. During power generation, the fuel cell releases water, which is used in ballast tanks to balance the AUV.

The high dive depth and range, as well as the ability to operate for an extended period of over two weeks, make the underwater vehicle ideal for long-term missions. Cellula sees potential applications in scientific missions as well as in military reconnaissance and for industry in monitoring and inspecting underwater pipelines and submarine cables.

To remain stationary underwater for an extended period, a special anchor from Solus-LR is installed. The anchor is lowered to the seabed via a winch. It consists of a type of suction bell surrounded by a rim that anchors into the seabed when the water is sucked out of the bell. Envoy switches to a power-saving mode where only monitoring sensors and minimal control systems are active. The AUV is intended to have a low acoustic signature, making it difficult to detect during military operations. If the journey is to continue, water is pumped into the suction bell to release the anchor.

During the test drive, which lasted more than two weeks, Envoy performed approximately 4000 turns and maneuvers. Cellula Robotics states that this increased energy consumption provided practical results for the mission.

(olb)