DemoSATH, the first floating offshore wind platform built by Ferrovial in Spain

DemoSATH is the first offshore wind infrastructure built in Europe. Ferrovial has built the second concrete offshore wind platform in the world and the first in Spain, in the port of Bilbao, off the northern coast of Spain. This project is a unique project, a huge concrete catamaran focused on producing energy for the future. Ferrovial has been responsible for the manufacture and assembly of the SATH floating platform, the first project of this kind to be carried out by the company.

“The Port of Bilbao was the scenario in which we built this pioneer and innovative project. It is the first project of this kind of works to be carried out by Ferrovial, which places us at the forefront of this type of special and innovative construction. Ferrovial has led this project at all levels, providing creative and innovative solutions to the original project, which have undoubtedly been key to its success and achievement. I am convinced that this is ont the end of the story, and that the experience and recognition that this project will give us will help us to position ourselves and grow in the emerging world of offshore wind energy“, highlights Alberto Val, Civil Works Manager for the Basque Country, Cantabria, Navarre and La Rioja.

Building DemoSATH

What is DemoSATH?

DemoSATH is the first Floating Offshore Wind platform in Europe. It is a floating solution off the coast of Spain developed by the client, Saitec Offshore Technologies and RWE, which positions wind turbines offshore to produce 2MW of energy that will be connected to the Spanish grid. The name “Demo” refers to the fact that it is the first plant to use the technology and “SATH” is the acronym for the floating structure: “Swinging Around Twin Hull”. The DemoSATH is made of modular, pre-fabricated components. The design has a single point of mooring, which means it aligns itself to the current and wave direction.

Ferrovial has been the construction company in charge of manufacturing and assembling the SATH floating platform. The DemoSATH prototype is a floating wind platform designed as a catamaran. The main elements of this platform are two pre-stressed reinforced concrete cylindrical floats placed horizontally (6), the SPM (Single Point Mooring) (1), which ensures maximum energy generation as it allows the platform to rotate and the rotor to be oriented against the wind, a transition piece (2), and the stabilising part (5).

Did you know that…?

  • The heaviest part of this structure is the conical segment, which weighs 470 tonnes.
  • The DemoSATH design aims to simulate the operation of a catamaran. It is a concrete (rather than steel) ship that is positioned offshore.
  • The project will provide enough electricity per year to meet the energy needs of 2,000 homes and avoid emissions of more than 5,100 tonnes of CO2 into the atmosphere, according to World Energy Trade.
  • During construction, some challenges have arisen, such as ensuring watertightness by redefining the number of joints or the assembly operation, which were transported with the 800-tonne crane.

“DemoSATH has been a different, very intense construction works. On this project, everything was new. Each construction process had to be defined, resized and calculated. The project has evolved and has been constantly redefined as the works progressed. This is the first prototype ever made in post-tensioned reinforced concrete in Spain, and the second to be built in the whole world, which has required additional efforts to calculate the elements. Some elements could not be built as originally defined by the client, because of interferences between the rebar, sheathing and embedded elements or because of a lack of assembly space. These were modified on site and with the new layout, the element was recalculated,” explains Enrique de las Cuevas, DemoSATH’s Site Manager.


  • Donna + Owens

    This is amazing!