Effect of Sea Current to Composites Cold Water Pipeline of Ocean Thermal Energy Conversion in Indonesia

Abstract

Ocean thermal energy conversion (OTEC) is a new source of future energy that is clean and environmentally friendly with zero emissions. It is very potential to be developed in Indonesia, which is located at the equator. to meet the electricity needs of the outermost and remote islands that are not currently covered by the main power plants in Indonesia. Indonesia has deep seas around the islands with temperatures of 5°C and surface temperatures above 25-28°C, so a temperature difference of 20°C can be obtained easily for OTEC power plants. Cold water supplied to the OTEC plant with a capacity of 2 MW at sea level requires a pipe with a diameter of 4 m and a length of 500 m. The pipeline must be insulating, not floating, corrosion-resistant, and resistant to current loads. Current is a very serious concern with the potential to cause pipe failure. The pipe material being investigated is a short fiberglass High-density polyethylene composite. In this study, a simulation of the effect of current on the composite pipe was carried out to obtain an overview of the stress that occurs and the proper pipe dimensions used. The highest current speed in Indonesian water is found in the Makassar Strait from July to September at 0.8 m/s at a depth of 100 m. Based on the OTEC Pro Simulation software for a capacity of 2 MW, resulted in the pipe size is 4 m and the pipe length is 500 m which refers to the temperature profile. In the simulation, the calculation of the dynamically moving current becomes the drag force on the pipe, and with the Autodesk inventor, it is known that the deflection in the pipe, and the yield stress cause failure in the pipe. Subsequently, from the deflection and yield stress data, a pipe thickness of 20-30 cm is obtained for the short fiberglass-HDPE composite material which is safe to use as an OTEC cold water pipe with a capacity of 2 MW. Pipes with a thickness smaller than 15 cm are too thin for a diameter of 4 m because the pipe wall has already experienced a deflection in a horizontal position and pipes with a thickness of > 30 cm are known from the simulation that the pipes cannot be connected rigidly and the pipes also experience stress due to current and pipe weight. so that the stress becomes greater in the pipe.