Semi-Submerged Marine Turbine Stabilization
Solution Overview
Problem
Existing solutions for extracting energy from marine and tidal currents face challenges such as reduced power capture due to depth-related current velocity reduction, complex and costly installation in deep water, and efficiency losses from wave-induced motions and forces in surface-floating devices.
Innovation Solution
A semi-submerged floating body with a specialized hull form and vertical struts supports a submerged turbine, minimizing wave-induced motions and using active lifting surfaces and asymmetrical struts to stabilize and align the device with current direction, allowing for efficient energy extraction with conventional mooring components and easy maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a surface floating body is used to support the turbine, then the device can be installed in deep water, but wave-induced motions and forces increase, reducing turbine efficiency and increasing design loads
Solution Approach 1:
The floating body transitions from a surface-floating configuration to a semi-submerged configuration, changing the vertical dimension of operation. The main body is positioned below the water surface while vertical struts extend above, operating in a intermediate dimension that avoids both surface wave effects and deep water constraints
Solution Approach 2:
The draft of the floating body is optimized to a specific range (0.5-2 times the significant wave height) to change the operational parameters. This parameter adjustment reduces wave-induced motions by positioning the main body in deeper, more stable water while maintaining accessibility for installation and maintenance
2Power
If the turbine is positioned deeper in the water column, then current velocity increases for power capture, but the device becomes more difficult to install and maintain
Solution Approach 1:
The vertical struts extend above the water surface, creating an above-water interface that provides access points for installation and maintenance operations without requiring the turbine itself to be exposed. This dimensional extension solves the accessibility problem while maintaining deep water turbine positioning
3Ease of manufacture
If conventional mooring components are used, then mooring and anchoring costs are minimized, but the device may not maintain stable alignment with current direction
Solution Approach 1:
Asymmetrical struts are employed to create directional stability and weathervaning capability. The asymmetrical configuration generates hydrodynamic forces that naturally align the device with the current direction, providing passive stabilization without complex active control systems or expensive specialized mooring components
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 enables efficient energy capture from marine currents with reduced wave-induced loads and costs, maintaining stability and performance across varying sea conditions, and facilitates easy installation and maintenance by aligning the turbine with the current direction.
Implementation Method 1
A number of different solutions exist for generating electricity through recovering the kinetic energy from ocean and tidal currents
Implementation Method 2
A semi-submerged floating body with a specialized hull form and vertical struts supports a submerged turbine
Data Source
AI summary
A floating, semi-submerged, tethered device that supports a horizontal axis turbine and power generation equipment for extracting kinetic energy from a tidal stream or ocean current. A submerged body (1) is supported by surface piercing struts (2) of small water plane area (FIG. 6). The device is tethered to the seabed by a spread of mooring lines (12) that are deployed both into and away from the direction of the tidal current. A horizontal axis turbine (4) harnesses energy from the water flow and drives a generator housed within the body. A horizontal strut hydrofoil (24) corrects the trim of the device when subject to varying loads from the mooring system and can also be used to dampen pitch motion. Rudder flaps in the struts (25) can be used to counteract roll motion. Power is exported from the device to the seabed by an umbilical (17). A thrusters (22) can be used to constrain the rotation of the device about its mooring system to prevent excessive twist building up between the mooring lines and the power export umbilical.