Floating offshore wind: what future?

In the national context, the high depths along the Portuguese coast make it impossible to install wind farms using fixed wind towers on the seabed, as is the case in the North Sea.

However, the need to install offshore wind farms at great depths boosted projects that made it possible to install floating wind turbines (FOWTs)6 at great depths. It is therefore accepted that the massification of offshore wind in Portugal is a plausible scenario, with the launch of tenders for the installation of floating wind turbines on the Portuguese coast as early as 202319.

In fact, the largest share of the wind resource is located in deep-water areas, so the offshore wind industry has been making a strong commitment to the FOWTs field. The investment in the technological development of the floating structure represents a large part of the investment (about 36% of the total cost of a floating turbine), however, this value is expected to decrease dramatically in the coming years with the industrialization of the technology. Even more, considering that these imply lower costs in terms of installation and geophysical and geotechnical studies of the marine subsoil4.

There are 3 major groups of floating wind turbines (FOWT's or floating offshore wind turbines): (i) Semi-submersible; (ii) Spar Buoy; and (iii) TLP – Tension Leg Platform.

The costs associated with the installation and transport of the last two are in fact quite high when compared to floating structures of the semi-submersible type. These, on the contrary, allow the use of a generic wind turbine tug system, already assembled, to the desired installation location, installation at low depths, transport of the complete structure for decommissioning and maintenance of the system in shipyards located in the areas port.

Everything points to the fact that offshore wind energy is essential to reach the target of 32% of energy from renewable sources by 2030 throughout the European Union, and that it will play an important role in the energy mix of tomorrow. For this reason, we also work on research, innovation and technology transfer.

In this field, INEGI has been working to solve problems associated with corrosion and fatigue of structures, which in the ocean are subject to an extremely aggressive environment. Within the scope of European projects, the work in the area of ​​advanced materials stands out, with the study of the use of materials based on fiber-reinforced polymers (FRP)13, and inspection, with the development of systems to assess the structural integrity and predict the structural behavior of underwater foundations and wind turbines14.

There is clearly a challenging and promising future for the development of offshore renewable energy, namely for offshore wind. Going further, especially in Portugal, requires the concerted involvement of R&D institutions, industry, society and decision-making centres.