Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.

OTEC(Ocean Thermal Energy Conversion) system using the temperature difference between cooler deep and surface ocean waters is one of the renewable energy. But in Korea, OTEC system can not apply except in winter because surface sea water temperature is not enough. C-OTEC(Combined OTEC) system is that utilizes temperature difference between sea water and the condenser of power plants via working fluid. It can be a good alternative in the warm surface sea water for Mid-latitudes region like Korea. In this study, a marine survey using multi-beam echo sounder, single-beam echo sounder and sparker seismic wave is performed and sea water intake pipe line is proposed for the 10kW C-OTEC Pilot Plant.