Wave Energy Converter Mooring with Buoyant Elements

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Solution Overview

Problem

Existing wave energy converters with acceleration tubes face issues with mooring systems that fail to maintain the device within a selected anchoring area, leading to reduced efficiency and increased maintenance needs due to slippage, line slack, and potential damage from wave movements.

Innovation Solution

The implementation of pretensioned mooring lines with buoyant elements and adjustable fastening devices, such as winches, to maintain the wave energy converter in a stable position and prevent line slack or tangling, while allowing for easy adjustment and reduced wear and tear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional mooring systems with fixing eyes and shackles are used, then the wave energy converter can be anchored at a selected position, but the mooring lines become slack during wave movements causing knots and damage

Engineering Contradiction:

Improvemooring line reliabilityVSAvoidline slack and knotting

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The mooring lines are pretensioned during installation to establish initial tension that prevents slack formation during wave-induced movements. This preliminary action ensures the lines remain taut throughout operation, eliminating the harmful slack and knotting that would otherwise occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the physical state of the mooring lines from slack to taut through controlled pretensioning. By adjusting the tension parameter during installation, the lines maintain optimal tension levels that prevent harmful slack formation while allowing necessary movement range

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If mooring lines are made taut to prevent slack, then the wave energy converter remains stable, but the fastening devices experience increased wear and slippage

Engineering Contradiction:

Improveanchoring position stabilityVSAvoidfastening device maintenance

Core Design Contradiction:

Stability of the object's compositionVSEase of repair

Solution Approach 1:

The mooring line system is segmented into multiple independent lines, each with its own fastening devices. This segmentation distributes the mechanical loads and wear across multiple connection points, reducing the stress on individual fastening devices and minimizing slippage and maintenance requirements

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Buoyant elements are integrated into the mooring line system to provide upward buoyant forces that counterbalance the downward gravitational forces and tension loads. This reduces the net tension in the mooring lines, thereby reducing wear and slippage at the fastening devices while maintaining stability

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Productivity

If the wave energy converter is allowed to move freely with waves, then it can harvest energy, but it drifts from the optimal anchoring position reducing efficiency

Engineering Contradiction:

Improveenergy harvesting efficiencyVSAvoidanchoring position maintenance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The mooring system is designed with dynamic characteristics that allow controlled movement within a defined area. The pretensioned lines and buoyant elements create a restoring force that guides the wave energy converter back toward the optimal anchoring position after wave-induced displacements, maintaining both productivity and reliability

Inventive Principle:

Principle #15Dynamics

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

This solution enhances the stability and efficiency of wave energy converters by keeping mooring lines taut, reducing the risk of damage and maintenance needs, and ensuring the device remains anchored in optimal conditions despite varying wave conditions.

Implementation Method 1

At least one of the mooring lines (111; 111') comprises at least one buoyant element (115; 115') attached between the first line section (112; 112') and the second line section (113; 113')

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP3277949B1Wave energy converter with mooring system comprising buoyant elements

Publication Date: 2020.12.02 W4P WAVES4POWER AB

Figure 1~2
Figure 3

AI summary

A wave energy converter (100) comprising a buoyant body (101) and an acceleration tube (102) attached thereto forming a working cylinder (103). Upper and lower openings in the acceleration tube (102) allow flow of water between the working cylinder (103) and the body of water (104) in which the acceleration tube (102) is at least partially submerged. The wave energy converter (100) has a working piston (105) reciprocable in the working cylinder (103) and an energy converting device (107) collecting energy from the movements of the working piston (105) relative to the buoyant body (101), and, furthermore, a mooring system (108) adapted to maintain the wave energy converter (100) within a desired anchoring area (109) and comprising at least a first fastening device (110) mounted on the buoyant body (101) for attachment of a first mooring line (111) to the buoyant body (101) and a second fastening device (110') mounted on the buoyant body (101) for attachment of a second mooring line (111') to the buoyant body (101), wherein the mooring lines (111; 111') comprise first (112; 112) and second line sections (113; 113'), respectively, and at least one buoyant element (115; 115') attached therebetween.