Gravity-Based Offshore Wind Support Structure Segmentation
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Solution Overview
Problem
Existing offshore wind turbine support structures, such as anchored floating structures and monopiles, are expensive and complex, especially for water depths above 80 meters, and monopiles are limited by diameter and handling challenges, while gravity-based structures face installation difficulties due to weight and size constraints.
Innovation Solution
A gravity-based support structure with a steel base and inclined hollow legs, tensioning members, and a steel upper part, allowing for a modular and vertically aligned installation process, enabling efficient installation in deep water depths with a height of 95 to 135 meters, using a tripod or pod-based design with ballasting for stability and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If monopiles are used for offshore wind turbines, then installation cost is reduced compared to jackets, but they become non-competitive above 30-40m water depths and are limited to shallow areas
Solution Approach 1:
The support structure is divided into a base portion and an upper portion that can be installed separately. The base portion is installed on the seabed first, then the upper portion is lowered and connected to it, allowing installation in deeper waters beyond the reach of single-piece monopiles.
Solution Approach 2:
The support structure transitions from a single vertical monopile to a multi-component system with inclined legs forming a tripod or jacket configuration, adding spatial dimensionality to achieve both economic efficiency and deep-water capability.
2Stability of the object's composition
If gravity-based structures with large concrete bases are used for water depths above 80 meters, then stability is improved, but the base becomes very heavy (over 15000 tons) and cannot be lifted by any ship or floating structure
Solution Approach 1:
The gravity-based structure is segmented into a base portion and an upper portion. The base portion weighs less than 15000 tons and can be lifted by available vessels, while still providing sufficient stability when installed on the seabed. The upper portion is then added separately to complete the structure.
Solution Approach 2:
The weight parameter of the base is reduced from over 15000 tons to under 15000 tons, making it liftable by available ships while maintaining stability through optimized geometry and material distribution.
3Strength
If monopiles with large diameters are manufactured, then structural strength is improved, but they become heavy and difficult to handle onshore and transport to offshore sites
Solution Approach 1:
The support structure is divided into multiple components (base portion, upper portion, legs) that can be manufactured, handled, and transported separately with lighter weights, then assembled on-site to achieve the required structural strength.
Solution Approach 2:
The support structure uses composite construction with steel legs and concrete base portions, combining the high strength-to-weight ratio of steel with the stability and cost-effectiveness of concrete to achieve both strength and ease of handling.
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 solution provides a cost-effective and less complex offshore electricity production assembly capable of installation in water depths exceeding 80 meters, with reduced logistical challenges and enhanced stability, outperforming existing solutions in terms of cost and installation complexity.
Implementation Method 1
a plurality of hollow legs protruding downwards from the connection piece and inclined with respect to the vertical direction, each of the legs being fixed to the base; and a plurality of tensioning members, each of the tensioning members being connected to lower extremities of two of the legs
Implementation Method 2
each of the lower part and the upper part comprising at least 90wt% of steel, the lower part and the upper part respectively and at least partly forming two blocks adapted for being lowered successively towards the seabed during installation
Data Source
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AI summary
An offshore electricity production assembly comprising a gravity-based support structure (12), and a wind turbine (14) defining a vertical direction (V), the support structure comprising: - a base (20) adapted for lying on a seabed (22); - a lower part (24) comprising: a connection piece (50) defining a housing (52); a plurality of hollow legs (38) fixed to the base; a plurality of tensioning members (54); - a hollow upper part (26) extending along the vertical direction, and including a connection portion (62) adapted for being received in the housing and fixed to the connection piece, each of the lower part and the upper part comprising steel, and respectively and at least partly forming two blocks (44, 48) adapted for being lowered successively towards the seabed during installation, and the support structure having a height (H) along the vertical direction comprised between 95 and 135 meters.