Preliminary Feasibility Study of an Ocean Thermal Energy Converter (OTEC) Platform for Offshore Brazil

Abstract

This study aims to identify the technical and operational challenges that impact the feasibility for the implementation of a 1MW (gross) Brazilian offshore Ocean Thermal Energy Conversion (OTEC) pilot plant. The OTEC technology utilizes the thermal gradient available between different layers (and depths) in the ocean to operate a heat engine to produce power output. It is expected to become mature enough to establish commercial power plants. The analysis is done by using coupled models in which ocean characteristics, the sizing of engineering apparatus and operational aspects of an OTEC plant are taken into account. A closed Rankine cycle with ammonia as the working fluid was considered for the plant. The Brazilian Blue Amazon is a geographic region defined along the Brazilian coast with a high potential for thermal gradient applications due to temperature gradients of more than 20 °C between sea surface and water depths of 600m z 1000 m throughout the year. This study focuses in such region, called CHT field, in Campos Basin. Campos Basin is an attractive location suitable for offshore floating OTEC plants in Blue Amazon that is also located near the Brazilian Offshore Oil fields. Because of this, a synergy may appear between Offshore Oil Production know-how and floating OTEC applications, since its clean and renewable energy source may also be used to Decarbonize FPSOs and other offshore structures. The available thermal power is analyzed in terms of an average annual estimated for the CHTfield, based on different thermal gradients. For each thermal gradient, the mass flows of sea Hot Water Pipe (HWP) and Cold Water Pipe (CWP), Working Fluid (WF), the pipe diameters, the WT, HWP and CWP pump capacities, and operational parameters of the offshore OTEC plant are calculated. One of the outcomes of this study is the possibility of analyzing greater operational capacities of offshore OTEC plants, such as 10 and 100 MW.