Harnessing the wind to decarbonize maritime transort
Wind-assisted propulsion is increasingly being considered as a solution for decarbonizing maritime transport. Mechanics researchers at ENSTA (IRDL Laboratory) are developing a set of physical models capable of evaluating and optimizing the energy performance of ships equipped with this technology. The French Maritime Academy (ENSM) will then integrate these physical models into a 3D simulator designed to train sailors, merchant navy officers and marine engineers.
Rigid sails, semi-rigid sails, kite sails and rotors are just some of the technologies being considered to propel the vessels of the future. But their development remains complex and their efficiency difficult to quantify.
The addition of sails changes the ship’s behavior by creating additional forces that interact with the hull and the propulsion chain, and its trajectory becomes more dependent on the weather conditions. This poses challenges in terms of both routing and operation.
Finding the optimal configuration
The interaction between wind-assisted propulsion systems and vessels is still poorly understood and lacks scientific evaluation. This is why ENSTA and ENSM launched the SOMOS project in January 2024, awarded the IngéBlue label and funded by the French Defense Innovation Agency (AID).
At ENSTA, Charles Dhainaut is developing physical models to simulate the complex forces and interactions between wind-assisted propulsion systems and ships. These models are integrated into innovative solver software, capable of simultaneously optimizing several aspects: the design parameters of the ship and the wind-assisted propulsion system, the control parameters (engine speed, rudder angle, propulsion system settings, etc.), as well as the route, simulated over a wide range of departure points spread over one year of operation. This results in a realistic evaluation of the ship’s performance.
A comprehensive approach that includes routing is absolutely essential: two different wind-assisted systems will not have the same effect on a given vessel. We take a highly comprehensive and modular approach to include as many parameters as possible in our optimizations, sometimes involving thousands of variables. The aim is to accurately estimate the potential fuel savings
explains Matthieu Sacher, Associate professor at ENSTA specializing in fluid-structure interactions.
The impact of the use of these future ships on the organization and safety of maritime transport will be studied by Martin Hochhausen, who will start his thesis in 2025, under the joint supervision of ENSTA and ENSM. This work will make it possible to integrate international navigation rules to prevent collisions at sea into the solver.
Training for crew
A navigation simulator developed by Florent Richard at ENSM will integrate the physical models with all their parameters (deploying sails, etc.). “This tool will be used to train crews in the use of future wind-assisted propulsion systems and to assess their operational impact,” explains Pedro Merino-Laso, head of sustainable development research at ENSM.
Fuel consumption estimates, routing algorithms and international navigation rules will be among the parameters tested using human-machine interfaces such as joysticks and touch screens.
Christophe Vanhorick will contribute his expertise in CFD modeling to optimize aero-hydrodynamic coupling, hull drift, interactions, balance and maneuverability.
Once finalized, all of the digital tools will be made available on an online platform for use by other stakeholders, such as universities and manufacturers, to encourage sharing and collaborative innovation.
An all-electric vertical axis thruster for greater energy efficiency
ENSTA, the French Naval Academy (École Navale) and the French National Institute for Ocean Science and Technology (IFREMER) are studying the performance of a new type of all-electric vertical axis thruster. A demonstrator will see the light of day next February, with full-scale tests planned for early 2026. The goal is to eventually equip various types of vessels - minehunters, offshore operations vessels, and wind-assisted vessels - to improve their efficiency, reduce their energy consumption, and lower their environmental impact.
Ensuring precise 360° thrust on a ship is no easy task. The Voith Schneider Propeller has been used to solve this problem since the 1950s. Its design features the rotation of multiple blades around a main axis, combined with the movement of each blade around its own secondary axis.
However, changing the pitch of the blades is based on a mechanical system that does not allow for the transition from “high” to “low” speed operation and vice versa.
An all-electric solution
To remedy this problem, teams from the French Naval Academy (École Navale) and ENSTA are working on an innovative solution: an all-electric vertical axis thruster. This system uses a main motor to rotate the blades and a motor for each blade to give it the optimal orientation for the desired propulsion. The actuators for each blade are electric, thus replacing the mechanical systems.
The advantage?
This ‘all-electric’ solution overcomes the limitations of mechanical drives,” explains Frédéric Hauville, Associate professor at the French Naval Academy (École Navale) and a specialist in fluid-structure interactions. “We can now generate any motion for each blade, allowing us to study a wide range of kinematics.
The orientation of the blades in relation to the direction of the ship is known as the “pitch law”.
The challenge of our project is to determine the optimal pitch laws to maximize propulsive power, and then to optimize the control and performance of the thruster using machine learning methods,
explains Matthieu Sacher, Associate professor at ENSTA and a specialist in fluid-structure.
A first thesis carried out by Guillaume Fasse at the French Naval Academy (École Navale), in partnership with ENSTA and French National Institute for Ocean Science and Technology (IFREMER), led to an initial optimization of the thruster’s hydrodynamic performance. Since 2023, the three organizations have been pursuing the development of the thruster as part of the SHIVA project, funded by the French Defense Innovation Agency (AID) and awarded the IngéBlue label.
Full scale tests scheduled for early 2026
A demonstrator equipped with 6 blades (a 4.2 kW main motor and 200 W for each secondary motor) is currently under construction. At ENSTA’s IRDL[1] Mechanics Laboratory, a CNRS Joint Research Unit, Guillaume Fasse is implementing thruster optimization methods, while at the French Naval Academy Research Institute (IRENav), Clément Douche is designing the future 6-blade prototype and Florent Becker is in charge of motor control.
The prototype is expected to be completed in February 2025, with ship model basin testing of the thruster’s behavior in relation to the hull scheduled for fall 2025.
In 2026, the propulsive performance of the thruster will be tested on a military vessel in the DGA Hydrodynamic Techniques Center’s ship model basin and on a WASP demonstrator in real-life conditions.
