Ocean Current Patterns and variability around Curaçao for Ocean Thermal Energy Conversion

Msc. thesis

Large-scale changes in ocean conditions caused by installing and operating Ocean Thermal Energy Conversion (OTEC) have not been studied in depth. Conversely, the effect on an OTEC plant by oceanographic features are not researched in depth either. The aim of this research is to describe the natural patterns and variability of the ocean currents around Curaçao, an island in the Caribbean Sea and a potential OTEC deployment location. This research is carried out in order to assess possible implications for the OTEC industry. Ten years of data from the Mercator Ocean Model with a spatial resolution of 1/12˚ and temporal resolution of one day was analyzed. The model is forced by wind data from ECMWF. A strong current jet is found to dominate the flow from east to west in the Caribbean Sea. The jet is identified as the Caribbean Current and it is forced by currents in the north equatorial Atlantic Ocean and large-scale wind patterns. The Caribbean Low Level Jet, an intensification of the Trade Winds over the Caribbean Sea, is strongest in winter and weakest in fall. Consequently, the current jet is found to have a peak from December to March and a trough in October and November. The largest surface velocities of the order of 1 m/s are found along the coast of Venezuela, where wind-driven upwelling enhances surface flow to the west. Along the Venezuelan coast, subsurface currents to the east, in the opposite direction to the surface currents, are also found. The period from April to September is characterized by the meandering of the jet and the formation of large (diameter > 200 km) anticyclonic eddies that cause large local surface velocities. These eddies contribute to the great variability observed in the Caribbean Sea. The origin of these eddies has not been clearly identified. Due to upwelling, no OTEC system should be deployed more than 50 km south of Curaçao to avoid cold surface water decreasing the system's performance. Hydrodynamic forces due to the calculated expected maximum velocity of 1.8 m/s, induce stresses in the cold-water pipe that do not exceed the yield stress.