Electric and Hybrid Propulsion Systems Help Drive Growth in USV Market

The global market for uncrewed surface vessels (USVs) is growing rapidly, and the rate is expected to accelerate. A recent research report projects a CAGR of 12.5 percent through 2025.

This growth rate is being driven by market demand for harvesting more high-quality survey data for a wide range of commercial and scientific applications and, on the supply side, by improvements in technology.

A key enabling technology is the advent of more reliable and durable battery-electric and hybrid propulsion systems with solar charging, replacing the fossil-fueled engines used in the past.

Torqeedo Inc. has been at the forefront of marine electromobility since its founding in 2005 and a driving force behind recent developments in electric and hybrid USV propulsion. Since 2017, Torqeedo has been part of the DEUTZ Group, a world-class manufacturer of innovative drive systems.

ELECTROMOBILITY REVOLUTION

To a large extent, the marine industry is benefitting from the massive R&D and engineering resources flowing into automotive electromobility programs. Most of the world’s largest car and truck manufacturers have announced aggressive schedules for switching their manufacturing over to electric or hybrid vehicles in the coming years. Major boatbuilders in the commercial marine and leisure boating segment worldwide are also looking to bring electric and hybrid boats to market.

Builders and operators of USVs are experts in integrating sensors and systems for gathering, communicating and analyzing data. They are not necessarily experts in marine propulsion systems, and they have typically installed commercial off-the-shelf gas or diesel outboards for power.

Most of them are now turning to more sustainable solutions. Electric boats produce less air and water pollution, offer quieter operation, less downtime, lower operating costs and savings in maintenance over the life of the vessel. There is also an obvious safety benefit in not having leaky gas lines or tanks of flammable liquids on board.

As battery capacity has improved in recent years, operating range and time on station has improved. Most survey work is done at relatively slow speeds of just a few knots, which results in much slower drawdown of battery capacity between charges.

Electric motors also have intrinsically better torque performance at slow speeds than internal combustion engines. In addition, station-keeping often requires rapid cycling back and forth between forward and reverse thrust. On an autonomous vessel, the use of a computer to rapidly shift gears can chew up a transmission quickly. The electric motors can switch from forward to reverse indefinitely without damage.

One of our customers, Don Darling, president of Sea Robotics, sums up the case: “USVs have the ability to transform many vessel intensive coastal and oceangoing activities. A greatly reduced carbon footprint is possible when vessel/ship crews are reduced or removed. Numerous manual tasks in the maritime environment are being assessed for the application of advanced automation and sensing systems making uncrewed vessels practical, and the electrification of the propulsion systems greatly reduces the carbon footprint for many tasks. Advances in battery and fuel cell technologies and integration of solar, wind and wave energy provide further benefit to the environment.”

We are currently working with several prominent USV companies to incorporate Torqeedo’s electric propulsion solutions on a range of vessels.

SWITCHING FROM GAS

Marine Advanced Robotics has developed a unique class of watercraft called WAM-V, which is based on a patented technology that radically improves seakeeping capabilities. Instead of pushing, slapping or piercing the waves, the flexible pontoon hulls continually adjust to conform to the water’s surface. Originally, the company used gas outboards which vented their exhaust underwater. The decision to develop an electric power package for the new WAM-V 16 model was driven by customers desiring to reduce noise and air pollution that can interfere with certain types of data collection. The company worked closely with Torqeedo’s engineering team to design an integrated propulsion system tailored to the specific mission requirements and unusual performance characteristics of the hull configurations.

The propulsion package on the WAM-V 16 consists of two Torqeedo Cruise 2.0 electric outboards with high-torque propellers, powered by multiple Torqeedo Power-series 24V lithium-ion batteries. Each motor provides propulsive power equivalent to a five-horsepower gas outboard. Kurt diSessa, operations manager for Marine Advanced Robotics reports that with the twin Torqeedo outboards and six batteries, the boat can do a full day’s work of 8-12 hours. The batteries can be charged overnight and be ready to do the same again the next day.

EXTENDED ENDURANCE ON STATION

When designing the new seven-meter SR-Endurance 7.0 ASV for underwater acoustic surveys, SeaRobotics had a set of very specific requirements, including dependable performance, extended time on station and quiet operation. Accordingly, the company worked with Torqeedo to develop a powertrain consisting of a 50-kW Deep Blue electric motor, a 360 VDC high-capacity lithium propulsion battery, a water-cooled DC-DC converter, a 24

VDC lithium battery for DC-DC backup and a 25-kW diesel generator. The system provides up to six days on station at survey speeds and up to 10 hours between recharges from the onboard generator. The recharging cycles are fully automatic under computer control.

The SR-Endurance 7.0 can operate under remote control by an operator ashore or semi-autonomously to implement a mission plan. All on-board systems are monitored with data connections to the remote base station. The operator can control all interfaces, view video feeds or put the ASV into automatic waypoint navigation mode, in which throttle and steering are under full computer control.

Accordingl to Darling: “The Deep Blue electric drive, with 80 horsepower-equivalent output, provides ample power for a wide range of towed or statically deployed systems. In addition, the smooth, continuous and rapid transition from forward to reverse thrust assists in station-keeping as well as near-dock maneuvering.”

LONG-DISTANCE REMOTE-CONTROL SURVEYS

XOCEAN, based in Ireland, provides turnkey underwater data acquisition services with a growing fleet of USVs. The company’s XO-450 UV is a custom-designed composite wave-piercing catamaran powered by a pair of Torqeedo Cruise 2.0 electric pod drives. Solar panels on deck provide efficient recharging during daylight hours, and the company estimates its vessels emit 1,000 times less carbon than traditional survey vessels. The two electric thrusters are controlled separately to adjust the speed on each side, steering the boat on the desired course. A pair of Torqeedo Ultralight outboards at the bows enhance station-keeping when gathering data. XOCEAN reports that the boat has an operating range of 1,500 nautical miles, providing up to 18 days of mission endurance running 24/7. The boats are under the remote command of qualified pilots at XOCEAN’s operations center, which monitors battery status and data quality using a broadband satellite transceiver on board.

XOCEAN has 13 USVs in operation with four more currently in build and expects to have a fleet of 40 USVs by 2022. They have operated in 14 countries, delivering over 100 projects including seabed surveys on 16 offshore wind farms.

This story was originally featured in ON&T June 2021. Click here to read more.