Buoyant Caisson Gravity Structure for Drill-Free Offshore Installation

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Solution Overview

Problem

Conventional gravity based structures for offshore wind turbines are costly due to the need for heavy lift vessels and are subjected to high hydrostatic pressures, requiring thick walls and anchoring techniques that drilling the seabed, which are not addressed by existing technologies.

Innovation Solution

A gravity based structure comprising a supporting system comprising a central column and a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine, comprising a supporting structure comprising a central column, a series of caissons, and a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine, comprising a supporting system comprising a central column and a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine, comprising a supporting system comprising a central column and a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional gravity based structures are used to support offshore wind turbines, then stability is provided through huge weight, but the structures become massive requiring heavy lift vessels and are costly to install

Engineering Contradiction:
ImprovestabilityVSAvoidstructure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The structure is divided into multiple caissons (at least three) distributed around the central column instead of using a single massive structure. Each caisson is a separate modular unit that can be independently manufactured and assembled, reducing the complexity of handling and installation while maintaining overall stability through distributed weight arrangement.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If huge gravity based structures are sunk into the seabed, then stability is achieved, but they are temporarily subject to huge hydrostatic pressure forces requiring thick walls and heavy lift vessels

Engineering Contradiction:
ImprovestabilityVSAvoidwall thickness
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The caissons are pre-filled with ballasting water and/or solid ballast before being lowered to the seabed. This preliminary ballasting allows the structure to control its sinking process and reach equilibrium position on the seabed without being subjected to full hydrostatic pressure forces during installation, thereby reducing the required wall thickness.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If monopiles are used in shallow waters, then wind turbines can be supported, but they require lifting and hammering into the seabed which are costly operations

Engineering Contradiction:
Improveinstallation easeVSAvoidinstallation complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The structure utilizes buoyancy forces from the caissons to lower itself into the water and settle on the seabed without requiring external hammering or drilling operations. The ballasting system enables the structure to control its own sinking and positioning, eliminating the need for costly hammering operations while maintaining installation simplicity.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed solution allows for the installation of the system comprising a supporting system comprising a central column and a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine, comprising a supporting system comprising a series of caissons, which are designed to allow for the introduction of water in the seabed and to support a wind turbine.

Implementation Method 1

the N caissons form hulls floating on the body of water

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

at least one of the N caissons is adapted for being flooded by water from the body of water via the opening

Methodology Applied
Scientific EffectHydrostatic pressure: Pressure Increase

Implementation Method 3

solid ballast intended to at least partly fill the N caissons

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4644610A1A gravity based structure
Publication Date: 2025.11.05 TOTALENERGIES ONETECH
  • EP4644610A1 patent drawingFigure 1
  • EP4644610A1 patent drawingFigure 2
  • EP4644610A1 patent drawingFigure 3

AI summary

A gravity based structure (12) comprising: - a supporting structure (20) comprising a central column (22), three or more caissons (24) defining an interior volume (38) and an opening (40), and inclined connecting legs (26), - a first system for introducing water in at least one of the caissons, and moving the supporting structure from a first equilibrium position, in which the caissons form hulls floating on a body of water (18), to a critical position, in which at least one of the caissons is flooded by water via the opening, the other ones being flooded via the opening as the supporting structure sinks and reaches a second equilibrium position, in which it floats in the body of water, - a second system for introducing ballasting water into the legs and/or the column and lowering the supporting structure from the second equilibrium position to a rest position on a seabed (16), - solid ballast intended to at least partly fill the caissons.