Cellula Robotics Envoy AUV completes 2,023 km fully submerged hydrogen fuel cell mission - 2026-04-24 - Capability - Cellula Robotics demonstrated more than 2,000 km of fully submerged endurance with its Envoy AUV powered by a hydrogen fuel cell system. The mission ran for 385 hours and covered 2,023 km underwater. The vehicle executed more than… - source: h2-tech.com