Conceptual design of a 10 MW shore-based OTEC plant

A 1982 study of a 10 MWe shore-based closed-cycle OTEC plant at Keahole Point, Hawaii, is updated to reflect advances in technology that have occurred over the past two years. Design options that show promise for reducing the capital cost of the plant are presented and are less conservative than those used in the earlier study. The options studied include the heat exchangers, the number and size of the cold-water pipes (CWP), the materials and method of construction of the CWP, and the CWP deployment technique. In all cases, the new options are within modest extrapolations of the current state of the art. Thermal-hydraulic optimization codes have been developed and used to upgrade and improve the design, and to focus on those components where significant cost reductions are possible. The power system has been improved with more cost-effective heat exchangers and a more water-efficient design. In addition, the long cold-water pipe associated with a shore-based plant warranted improved design concepts that appear to lead to lower costs. In the original study, the heat exchangers were shell-and-tube units, with plain, titanium tubes. An advanced option has been selected that uses compact, brazed-aluminum heat exchangers, whose lifetime usability is encouraged with recentmore » data from the Seacoast Test Facility in Hawaii. The new design has replaced the original single-piece, 5.2 m diameter cold-water pipe with a 4.1 m diameter equivalent unit. This study reviewed options for parallel or bundled pipes of smaller (2 meter) diameter; although less efficient hydrodynamically than a single, large pipe, the smaller diameters present fewer fabrication problems, and potentially simpler deployment methods. Also studied are various options for CWP materials and construction.« less