Simplified Formulation of Coupled System Between Moored Ship and Elastic Pipe for OTEC Plantship

2021 ◽  
Author(s):  
Ryoya Hisamatsu ◽  
Tomoaki Utsunomiya
Keyword(s):  
Numerical Simulation ◽  
Cold Water ◽  
Early Stage ◽  
Large Diameter ◽  
Coupled System ◽  
Equation Of Motion ◽  
Floating Body ◽  
Floating Platform ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

Abstract A commercial-scale Ocean Thermal Energy Conversion (OTEC) floating platform will require a large diameter Cold Water Pipe (CWP) to be attached. Several studies have analyzed the dynamic behavior of the coupled system between the floating platform and the CWP. However, the characteristic of the coupled behavior has not yet been fully understood. This study aims to formulate the coupled system of an OTEC floating plant and simplify the formula to clarify the characteristic of the coupled behavior. The formula is suitable for validation of the numerical simulation results and the preliminary design of an OTEC plant. In the first section of this paper, we derive the equation of motion and equilibrium of the direct moored floating body and an elastic pipe hanged off from the floating body. In the second section, we verify the formula for a 100MW OTEC plantship with 800m length and 12m diameter CWP. The Response Amplitude Operator (RAO) is calculated by solving the equation of motion and statistics responses in 3 hours are compared with a numerical simulation by OrcaFlex. As the result of the comparison, we observed that the present formula is applicable in the early stage of the practical design loop.

Analysis and Design of the Cold-Water Pipe (CWP) for the OTEC System with Application to OTEC-1

1980 ◽  
Vol 17 (03) ◽  
pp. 281-289
Author(s):  
Allan T. Maris ◽  
J. Randolph Paulling
Keyword(s):  
Cold Water ◽  
Large Diameter ◽  
Deep Ocean ◽  
Water Pipe ◽  
Floating Platform ◽  
Pipe System ◽  
Analysis And Design ◽  
Thermal Energy Conversion ◽  
Diameter Pipe ◽  
Ocean Thermal Energy

OTEC--Ocean Thermal Energy Conversion--currently requires a large floating platform and a 1000-metre-long, large-diameter pipe to supply deep ocean cold water. The design of the pipe in this system requires the development and application of analysis procedures to determine the response of the coupled platform pipe system to sea loadings. This paper discusses the development of the analysis procedures and the results of the application of these procedures to several pipe designs which appear feasible for an OTEC-1 MW power plant system.

Preliminary Design of a 1-MWe OTEC Test Plant

1982 ◽  
Vol 104 (1) ◽  
pp. 3-8 ◽  
Author(s):  
T. Kajikawa
Keyword(s):  
Cold Water ◽  
Working Fluid ◽  
Test Plant ◽  
Mooring System ◽  
Preliminary Design ◽  
Closed Cycle ◽  
Water Pipe ◽  
Thermal Energy Conversion ◽  
Design Value ◽  
Ocean Thermal Energy

An ocean-based, 1-MWe (gross) test plant has been planned to establish the feasibility of OTEC (ocean thermal energy conversion) power generation in the revised Sunshine Project. The preliminary design of the proposed test plant employs a closed-cycle power system using ammonia as the working fluid on a barge-type platform with a rigid-arm-type, detachable, single-buoy mooring system. Two types each of titanium evaporators and condensers are to be included. The steel, cold-water pipe is suspended from the buoy. The design value of the ocean temperature difference is 20 K. The paper presents an overview of the preliminary design of the test plant and the tests to be conducted.

The Ocean Thermal Gradient Hydraulic Power Plant and Its Scope

2003 ◽  
Author(s):  
Earl J. Beck
Keyword(s):  
Power Plant ◽  
Thermal Gradient ◽  
Cold Water ◽  
Working Fluid ◽  
Hydraulic Power ◽  
Tropical Oceans ◽  
Thermal Energy Conversion ◽  
Near Shore ◽  
Power Outputs ◽  
Ocean Thermal Energy

Heretofore, the concept of developing power from the tropical oceans, (Ocean Thermal Energy Conversion, or OTEC) has assumed the mooring of large platforms holding the plants in deep water to secure the coldest possible condensing water. As the Ocean Thermal Gradient Hydraulic Power Plant (OTGHPP) does not depend, on the expansion of a working fluid, other than forming a foam of steam bubbles. It does not need extremely cold water as would be dictated by Carnot’s concept of efficiency and the 2nd Law of Thermodynamics. Plants may be based on or near-shore on selected tropical islands, where cool but not extremely cold water may be available at moderate depths. This paper discusses the above possibilities and two possible plant locations, as well as projected power outputs. The location and utilization of large of amounts of power on isolated islands, where cabling of power to major population centers would not be feasible are discussed. Two that come to mind are the reduction of bauxite to produce aluminum and the of current interest is the electrolyzing of water to produce gaseous hydrogen fuel to be used in fuel cells, with oxygen as a by-product.

OTEC Cold Water Pipe Global Dynamic Design for Ship-Shaped Vessels

2013 ◽  
Author(s):  
Sherry Xiang ◽  
Peimin Cao ◽  
Richard Erwin ◽  
Steve Kibbee
Keyword(s):  
Cold Water ◽  
Dynamic Performance ◽  
Dynamic Responses ◽  
Outer Diameter ◽  
Water Pipe ◽  
Floating Platform ◽  
Reinforced Plastics ◽  
Global Dynamic ◽  
Offshore Industry ◽  
Ocean Thermal Energy

Ocean Thermal Energy Conversion (OTEC) technology has been considered as a renewable power generation for the tropical oceans where a thermal gradient from subsea to surface are higher than 20°C since 1980. In 2009, the OTEC technical readiness report has identified that semi-submersible, ship-shaped vessel and spar are most feasible to OTEC application. All three are technically mature and well-established floating facilities and have been widely manufactured and operated in offshore industry all over the world. A pilot OTEC development, led by Lockheed Martin (LM) Industry Team, has configured a semi-submersible floating platform. As an alternative design, SBM is developing OTEC designs based on converted ships. Ship shapes provide good access to facilities for practical operation and maintenance activities. Our study focused on demonstrating the feasibility of constructing and installing a 4 meter outer diameter Cold Water Pipe (CWP) based on conventional land-based manufacture of Fiberglass Reinforced Plastics (FRP) followed by installation with SBM marine equipment. Based on insights gained from this exercise, we will continue to develop the installation methods for larger diameter CWPs. The CWP is a key design challenge for OTEC since it must be strong enough to withstand the forces and motions while being light enough to be installed with available marine equipment. This paper focuses on the cold water pipe global dynamic performance hosted by a converted ship for a 10MW OTEC plantship offshore Hawaii. The offshore Hawaii location was selected for purposes of comparison rather than the existence of any specific prospective projects. The CWP is connected to the vessel via a sealed gimbal device that allows the CWP’s angular motions to be decoupled from the vessel. The fundamental understanding of CWP vibrations is discussed. The CWP global dynamic responses to extreme storms and operational fatigue environments are presented. Vortex Induced Vibration (VIV) and other design issues are discussed. The key global design considerations of CWP for the ship-shaped vessel are identified and summarized.

scholarly journals Potential Ocean Thermal Energy Conversion (OTEC) in Bali

KnE Energy ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 5 ◽  
Author(s):  
Adrian Rizki Sinuhaji
Keyword(s):  
Renewable Energy ◽  
Cold Water ◽  
Power Production ◽  
Maximum Efficiency ◽  
Thermal Distribution ◽  
The North ◽  
Thermal Energy Conversion ◽  
Minimal Difference ◽  
Ocean Thermal Energy ◽  
Better Than

<p>OTEC is a method for generating electricity which uses the temperature difference that exist between deep and shallow water with the minimal difference about 20°C. This paper aim to determine the potential and the provision of new and renewable energy in Indonesia.OTEC is very compatible build in Indonesian sea because Indonesia is placed in equator teritory, a lot of island, strain and many difference of topography especially in North Bali Sea. A calculation ocean thermal distribution in Indonesia for OTEC is doing with statistics from ocean thermal surface.The maximum efficiency of carnot engine (ηmax) is obtained in the North Bali Sea by 0.788813. Figures are better than other regions in the Indonesia. OTEC power production is renewable energy that could be a solution to produce electricity, and also can produce fresh water and cold water for agricultural and cooling purposes especially in the tourist area like Bali. </p><p><em><strong>Keywords</strong></em>: OTEC, Bali, Temperature, Renewable Energy </p>

Dynamic Positioning of a Floating OTEC Plant Using Current-Derived Forces

1989 ◽  
Vol 26 (03) ◽  
pp. 233-244
Author(s):  
Warren E. Bucher
Keyword(s):  
Gulf Stream ◽  
Cold Water ◽  
Equations Of Motion ◽  
Surface Current ◽  
Dynamic Positioning ◽  
Dynamic Positioning System ◽  
Thermal Energy Conversion ◽  
Vertical Speed ◽  
Positioning Method ◽  
Ocean Thermal Energy

A study is performed to determine whether Ocean Thermal Energy Conversion (OTEC) platforms can be dynamically positioned by the use of forces derived from ocean currents. The dynamic positioning characteristics of a 40-MWe spar buoy configured plant are simulated by computer solution of the equations of motion. The dynamic positioning system consists of two large vertical vanes attached to the plant's cold-water pipe. The vanes act as underwater sails and, where the current has a vertical speed gradient, may be operated such that the resulting hydrodynamic force and plant velocity have components directed upstream to the surface current. Forces on and motions of the plant are determined for operations in Hawaiian currents and in the Gulf Stream. The dynamic positioning method is shown to be theoretically feasible.

Coupled Analysis Approach in OTEC System Design

2012 ◽  
Author(s):  
Shan Shi ◽  
John Halkyard ◽  
Nishu Kurup ◽  
Lei Jiang
Keyword(s):  
System Design ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Cold Water ◽  
Large Diameter ◽  
Working Fluid ◽  
Coupled Analysis ◽  
Ammonia Vapor ◽  
Water Pipe ◽  
Floating Platform

Ocean Thermal Energy Conversion (OTEC) technologies based on floating platforms generate electrical energy by utilizing the temperature difference between the deep ocean water and the surface water. One typical offshore floating OTEC system uses the temperature difference to drive a heat engine, utilizing a closed-loop Rankine cycle with a working fluid such as ammonia (NH3). Cold water is pumped through a large flexible pipe from approximately 1000m depth to heat exchangers which condense the ammonia vapor. Warm water from the surface is pumped through heat exchangers to evaporate the liquid ammonia to drive the turbine. An OTEC floating platform could be a semisubmersible, a spar, or other typical offshore hull form with a taut or a catenary mooring system. As opposed to oil and gas production platforms, the OTEC system consists of a large diameter cold water pipe (CWP) which will participate in the global performance of the floating platform. Its unique behavior also includes the contribution of CWP entrained water which behaves differently in lateral and vertical directions due to its open bottom design. The hydrodynamic behavior of the large scale cold water pipe is an important consideration in the system design and analysis. The study presented in this work includes the application of a fully coupled analysis program with an accurate cold water pipe dynamic model in OTEC floating system analysis. The study could be useful for future guidance and reference on OTEC floating platform designs.

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