Alternative energy transmission systems from OTEC plants. Project 8980 third quarter progress report, January 1--March 31, 1977. [Study on 4 thermal storage systems

Abstract

Three types of thermal energy storage media were considered for transport of OTEC energy. They were the following: (1) sensible heat media, which depends upon the heat capacity of the material for energy storage, (2) latent heat of fusion material, and (3) reversible chemical reactions, which depend upon the change in energy content of certain compounds as chemical bonds are broken and other bonds are made. Only those systems operating in the nominal temperature range of 400/sup 0/ to 1000/sup 0/F were considered. The lower limit of the temperature swing of sensible heat thermal energy systems was approximately 400/sup 0/F. A literature search was undertaken and completed. As a result of the literature search, four thermal energy transport system concepts were selected and synthesized into conceptual systems that use OTEC energy to charge the thermal storage medium installed in a ship hull, then transport the heat storage system to shore for use, or convert the thermal energy to electricity using a heat engine. The four conceptual designs, of which two used sensible heat storage, one used the latent heat of fusion, and one used a reversible chemical reaction, were derived from thermal energy storage conceptual designs for solar thermal-electric powermore » plants or solar total energy systems. The four thermal energy transport systems were: (1) rock/oil hybrid - a sensible heat storage system using crushed gravel rock and a heat transfer fluid, Caloria HT-43; (2) HITEC - a sensible heat storage system using a molten salt; (3) sodium hydroxide - a latent heat of fusion system also using sensible heats of liquid and solid phases; and (4) sulfur trioxide/sulfur dioxide - a reversible chemical reaction system using the following reaction: SO/sub 3/ + Heat reversible SO/sub 2/ + /sup 1///sub 2/O2. Results of a cost/efficiency analysis of the four systems are tabulated and discussed. (WHK)« less