Concept Design of a 10 MW Ship-Shaped OTEC Plant

Abstract

The purpose of the research is to provide insight into the conversion of a second-hand vessel into an Ocean Thermal Energy Conversion (OTEC) plant. To this end, a 10 MW ship-shaped OTEC platform, located in the waters around Curaçao, has been designed.
At present, only a few of OTEC plants are in operation, primarily with the purpose of research and development. These projects consist of small scale onshore platforms, the biggest of which produces a maximum of 100 kW of continuous electricity. The lack of existing large oshore OTEC installations, together with the time frame of the project, limit the project to a concept design. Ultimately, the report will serve as a guideline for the implementation of ship-shaped OTEC platforms.
The use of Systems Engineering (SE) has been motivated by the need to establish a clear structure to address effectively the challenges posed by the complexity of the installation. This methodology facilitates the revision of the performance of the ship-shaped OTEC throughout the design process.
From the initially defined Top Level Requirements (TLRs) a plant architecture has been developed, covering the engineering of the power plant, selection of mooring system and dimensioning of the second-hand Panamax bulker to be converted. The research has brought forward the main drivers of the design: process ducting, water pipes and, particularly, heat exchangers. As a result, the integration of process equipment, mooring system and hull has rendered an optimized platform layout.
The proposed solution was, then, assessed with regards to the utilization of space on board and the stability of the hull. While the ratio of occupied versus empty space is deemed adequate, it is necessary to add ballast water to increase the draft and the use of alternative solutions, such as bilge keels or fixed ballast in the top side tanks, to dimish the excess of stability of the hull.
Overall, the findings of the research suggest that the construction and operation of a ship-shaped OTEC plant is feasible. Nevertheless, a holistic validation demands for the incorporation of all new components, followed by structural and hydromechanic analysis of the platform. Lastly, it is recommended to study the use of different heat exchanger types and power ouputs that could derive in more space-efficient
design.