Concept Developments for Offshore Thermal Energy Conversion Platforms

This paper discusses studies leading to the concept design of two platforms to support the Department of Energy's Offshore Thermal Energy Conversion (OTEC) mission in the 1980's. The first part of the paper discusses the technical and economic factors evaluated in the selection of optimum plant size and configuration. Variables included a range of capacities from 50 to 500 MW, six hull-form options and three deployment sites. Parametric trends in platform size and weight as a function of payload and hull shape are evaluated. A methodology for evaluating the various platform options is presented, based upon consideration of cost, schedule and risk, leading to recommendations for an optimum plant. The second part of the paper describes the development of the conceptual design of two selected commercial plant candidates, a ship and a semisubmersible, each of 400-MW net output, to be deployed off Hawaii. Initial tradeoff studies are described and selected platform characteristics are provided. Methods of plant fabrication and deployment are proposed, with emphasis on cost/schedule relationships. Finally, concepts are presented for a demonstration plant which will prove the technical and economic feasibility of OTEC before commitment to the prototype commercial plant.