In partnership with bound4blue, a developer of wind-assisted propulsion technology, Odfjell. a leader in the global market for seaborne transportation and storage of chemicals and other specialty bulk liquids, will install the innovative eSAIL system on a chemical tanker, making it the first tanker vessel to harness this technology.
Hudong vessel with bound4blue suction sails. Illustration by NagellD
bound4blue has developed autonomous rigid sails systems (eSAIL and Wingsail) to be integrated on a wide range of vessels. The systems have been conceived as a complementary propulsion system, which produce effective thrust from existing winds, reducing the main engine power required and, therefore, delivering fuel consumption and pollutant emissions reductions of up to 40%. bound4blue says the payback period is under 5 years.
The eSAIL is a type of Wind-Assisted Propulsion System (WAPS) based on active boundary layer control using suction. When exposed to wind, with the suction off, it only produces drag as with any other non-lifting structure. However, when the suction is activated, a small amount of air is sucked in, which re-adheres the airflow to the sail, generating enormous amounts of lift with low drag.
The eSAIL produces 6-7 times more lift than a conventional sail, with minimal power consumption and no mechanical complexity (no inertial loads, vibrations, constant movement, etc.) ensuring simple and reliable operations.
The suction fan is a standard axial compressor driven by an electric motor. It is responsible for sucking in the air to ensure the airflow remains attached to the sail.
The suction area is a porous area of the skin through which the air is sucked. It is strategically designed and located to ensure airflow remains attached to the eSAIL with minimal power consumption.
The geometry of the eSAIL inverts depending on whether the wind blows from port or starboard. The flap is a movable structure, manufactured using marine-grade materials, that can be positioned on both sides of the eSAIL, generating the appropriate aerodynamic shape of the eSAIL and, at the same time, covering the suction area that is not in use. Positioning the flap is done using standard electric motors.
The main structure and skin of the eSAIL provide the external aerodynamic shape of the sail and, at the same time withstand all loads that affect the eSAIL. It is manufactured using marine-grade materials and also contains and protects the equipment located inside.
The autonomous control system efficiently operates the eSAIL with no intervention from the crew. Based on the input data received from several sensors, it operates the actuators to position the eSAIL and the flap to the optimal position and adjusts the suction power, minimizing its consumption.
The rotation system ensures that the eSAIL can rotate to orient towards any existing wind direction. It is based on a standard slew-bearing actuated by an electric motor. This part is very similar to a deck crane.
The eSAIL mechanically connects to the vessel by means of a flange, which is secured using bolts. Again, this is a well-known solution, based on standard deck cranes.
Odfjell has actively pursued decarbonization initiatives for many years, and recently documented a 51% improved carbon intensity compared to the 2008 baseline. The deployment of bound4blue’s eSAIL system represents another milestone in the company’s implementation of solutions to increase its fleet’s energy efficiency.
Odfjell's partnership with bound4blue aims to expand access to the eSAIL technology within the tanker shipping segment and further contribute to the industry’s efforts in decarbonization. The decision to collaborate with bound4blue was supported by an extensive study conducted by SSPA, evaluating various Wind Assisted Propulsion Systems (WAPS) for the Odfjell fleet. The pioneer installation will be completed in 2024.