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

Abstract

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.