Farwind has led to the development of a multihull that is fully propelled by the wind. And as it sails, water turbines underneath are powered to generate electricity. The harvested energy is stored on board and brought to shore.
At societal level, such a project could make a big impact and help to deliver zero emission fuels, improving problematic availability in areas with little infrastructure. On the technical level, the project is interesting because it integrates automated wind propulsors with a tidal turbine.
MARIN was given the chance to contribute within the broader frame of the Marine Energy Alliance Interreg project. Farwind had been doing its own modelling and concept development and was now in need of some review work and consultancy regarding various design options. MARIN’s review showed that Farwind had been comprehensively covering the entire performance but there were some points needing attention.
Farwind’s CTO Aurélien Babarit commented: “A key challenge in the energy ship concept is to develop an appropriate design for the water turbine. Indeed, the common designs for tidal turbines maximises the power coefficient without paying attention to thrust. However, with a sailing craft, increasing the power coefficient also brings down the ship speed, thereby decreasing the apparent wind over the Flettner rotors and generally lowering the flow speed over the turbine. The optimum working point is thus at a much lower loading, which is completely different compared to existing tidal turbines.”
Similar challenges are relevant for the sailing performance. Interaction effects (with multiple devices both above and below the water) can have a significant impact on overall performance.
MARIN’s contribution indicated ideas for design improvements, as well as methods to improve performance predictions. Our contribution may be modest, but such early involvement can sometimes have the largest impact down the road. We wish Farwind every success with their concept!
The Marine Energy Alliance project is funded by Interreg North-West Europe.
References A. Babarit, G. Clodic, S. Delvoye, J-C. Gilloteaux (2020) Exploitation of the far-offshore wind energy resource by fleets of energy ships – Part 1: Energy ship design and performance. Wind energy science, Vol. 5, 839-853