Innovative environmental conditions classification to unlock standardization and mass manufacturing of floating offshore wind turbines

About the Project

BACKGROUND: FLOATING WIND TURBINES

High costs and very slow deployment rates of floating offshore wind turbines (FOWTs) are preventing the UK offshore wind sector from reaching its target of 5 GW of FOWT capacity by 2030 (currently at approximately 0.07 GW).

Standardization and mass production are urgently needed; however, there are currently around 100 proposed designs, with no convergence towards a few proven concepts.

Classification societies (e.g., DNV [1]) have suggested the definition of “environmental classes,” which would allow FOWT systems to be designed for a class of environmental conditions rather than for site-specific ones. This approach recognizes that overengineered, but mass-produced, standardized systems can achieve cost savings compared to bespoke, wind farm-specific designs.

The widely accepted “wind turbine class” system by the IEC [2] partially achieves this by defining a finite set of wind conditions, enabling wind turbine generator OEMs to focus on a limited set of designs. However, a similarly accepted approach that considers the other metocean parameters to which a FOWT is subjected (i.e., waves and currents) does not yet exist. Defining such an approach poses several challenges:

• What are the limiting environmental conditions, among all possible, that drive the design of FOWT support structures in the early design phases?
• For each environmental condition (wind, waves, etc.), what is a suitable set of representative variables that quantify the loading regime, yet avoid requiring an excessive number of parameters that would hinder the definition of a practical set of environmental classes?
• For each variable, how can “severity thresholds” be robustly defined based on the underlying physics, while remaining interpretable?

PROPOSED AIMS AND OBJECTIVES

The aim is to develop a methodology for defining simple, adaptable environmental classes that balance usability with accurate environmental representation. It will provide a framework for FOWT substructure designers to identify and characterize these classes based on their individual criteria. This aim is broken down in five objectives.

1. Definition of the design load cases (DLC) driving the design of floating offshore wind turbine support structures
2. Definition of the critical set of environmental conditions representing the design-driving DLCs
3. Collection of the values of the critical set of environmental conditions for a given geographical region (Scotland Exclusive Economic Zone)
4. Development of a robust methodology to derive unbiased, data-driven severity level thresholds, defining the "environmental classes", based on the clustering statistical data analysis approach.
5. Application of the methodology developed to a specific geographical region, as a case study, performing a sensitivity analysis between number of environmental classes and extension of the area covered by each environmental class.