Submersible Frame for Horizontal Buoyant-Tank Seabed Storage

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Solution Overview

Problem

Existing systems lack a modular and efficient method for storing pressurized gas tanks, such as hydrogen, on the seabed while ensuring they remain securely positioned and accessible for connection, particularly in locations with intermittent renewable energy sources.

Innovation Solution

A subsea system comprising a frame structure with cradles and fastening devices that allow tanks to be horizontally stored with positive buoyancy, secured to prevent upward floatation, and modularly expandable to meet varying storage needs, using materials with negative buoyancy to ensure stable seabed placement and easy access for connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If tanks with positive buoyancy are stored horizontally on the seabed, then accessibility for connection is improved, but the tanks tend to float upward requiring additional securing mechanisms

Engineering Contradiction:
Improveaccessibility for connectionVSAvoidupward floatation force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The frame structure is designed with negative buoyancy to counterbalance the positive buoyancy of the tanks. The frame comprises at least two vertical legs extending downward from horizontal beams, with the vertical legs providing downward force to counteract the upward floatation of the horizontally positioned tanks, thereby securing them on the seabed without requiring additional active securing mechanisms

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Adaptability or versatility

If a modular system with multiple storage positions is used, then adaptability to varying storage needs is improved, but device complexity increases

Engineering Contradiction:
Improvemodular expandabilityVSAvoidframe structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The frame structure is segmented into modular components including horizontal beams and vertical legs that can be configured in different arrangements. The frame may comprise one or more horizontal beams with storage positions therebetween, and one or more vertical legs extending downward, allowing the system to be scaled from single-tank to multi-tank configurations without requiring completely different designs for each storage capacity

Inventive Principle:
Principle #1Segmentation

3Reliability

If tanks are secured firmly to prevent movement, then reliability is improved, but ease of installation deteriorates

Engineering Contradiction:
Improvetank positioning stabilityVSAvoidinstallation ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The fastening devices are designed to be dynamic rather than permanently fixed, allowing them to be easily attached and detached. The vertical legs include fastening devices that can securely hold the tanks in position during operation but can be quickly released when installation or removal is needed, providing both stability during use and ease of installation

Inventive Principle:
Principle #15Dynamics

4Stability of the object's composition

If the frame structure uses materials with negative buoyancy, then stability on seabed is improved, but weight of the structure increases

Engineering Contradiction:
Improveseabed placement stabilityVSAvoidframe structure weight
Core Design Contradiction:
Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The frame structure utilizes materials with negative buoyancy (density greater than water) such as metals like steel or aluminum. By changing the material parameter from buoyant materials to negatively buoyant materials, the frame itself provides downward force that stabilizes the entire structure on the seabed and counteracts the positive buoyancy of the tanks, eliminating the need for additional heavy ballast while maintaining stability

Inventive Principle:
Principle #35Parameter changes

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 system enables secure, stable, and accessible storage of pressurized gas tanks on the seabed, facilitating easy installation and expansion, while minimizing the risk of floatation and enhancing safety and operational efficiency.

Implementation Method 1

a frame structure for horizontal storage of tanks with a positive buoyancy in water therein, wherein the frame structure has a negative buoyancy in water

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP4308845B1Submersible system for storing tanks and method of storing tanks on a seabed
Publication Date: 2025.08.13 FMC KONGSBERG SUBSEA AS
  • EP4308845B1 patent drawingFigure 1A
  • EP4308845B1 patent drawingFigure 1B
  • EP4308845B1 patent drawingFigure 2A

AI summary

The invention relates to a submersible system (1) comprising at least a first frame structure (2) for horizontal storage of tanks (3) with a positive buoyancy in water therein, wherein the first frame structure (1) has a negative buoyancy in water and comprises at least two storage positions (4) for supporting at least two tanks (3), wherein the storage positions (4) are arranged side by side in one level and each storage position comprises at least one cradle (4) for supporting a tank (3) from below, and wherein the system (1) comprises a fastening device (6,11) having a first and a second state, wherein: i. when in the first state, the fastening device (6,11) is configured to permit positioning of a tank (3) from above into the at least one cradle (4) and; ii. when in the second state, the fastening device (6,11) is configured to secure a tank (3) positioned in the at least one cradle (4) in a radial direction of the tank (3) preventing movement of the tank (3) in a vertical upward direction; and wherein a total buoyancy of the system (1) when submerged in water, when tanks (3) are positioned in each of the storage positions, is negative. The invention also relates to an associated method of storing tanks on a seabed using the submersible system (1).