Sabella designs new hybrid gravity-based foundation for tidal turbines

French tidal energy company Sabella has finalized the design of the new gravity-based foundation for tidal turbines which combines concrete and steel for greater cost-competitiveness.

The new concrete and steel foundation has been designed as part of OCEAN-ERA Net Co-Fund project CF2T, which in addition to Sabella brings together Saitec, Allia, Reseach Institute of Swede (RISE) and Alkit.

The objective of the project was to design and develop a competitive foundation for a tidal turbine by combining concrete and steel in order to reduce manufacturing costs and increase the life of the supporting structure.

The work carried out also made it possible to make the foundation modular, allowing it to be installed in several packages in order to limit the lifting capacity required for the installation vessel and reduce the costs of operations at sea, according to Sabella.

This modularity also makes it possible to reduce the CO2 emissions associated with the manufacturing and installation of this hybrid structure by 22% compared to the previous steel one, the partners said.

In addition, a dedicated monitoring system has also been developed to improve knowledge of the loads applied to the foundation and to monitor its structural health to improve its reliability.

The novel hybrid foundation solution should be implemented on all of Sabella’s future projects, the company said.

Sabella has a number of tidal energy projects currently in development – most notably the EU-backed TIGER project. As part of the project, Sabella plans to deploy two 250kW D8 turbines at the site in the Gulf of Morbihan in France.

The project, developed by UK and French partners, aims to accelerate the growth of tidal stream energy by installing up to 8MW of new tidal capacity at sites in and around the English Channel region.

More recently, Sabella secured a 12MW berth off the coast of Anglesey, together with its partner Nova Innovation.

The companies already started surveys at Morlais site and are looking to install their first turbines in 2023/24.