A novel combined OTEC/SWRO plant

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.

All actual Ocean Thermal Energy Conversion plants (OTEC) that have been built or designed to date have been at sea level or above. While the concept of OTEC is more than 100 years old, the application has been very limited primarily because of the cost of the plant and the power it produces in comparison to other sources of power. Since OTEC plants are very inefficient (around 3%), huge amounts of low-grade heat must be supplied and rejected. Some authorities estimate that the cost of piping cooling water from some 1000 meters below the ocean surface represents nearly half of the plant cost. The purpose of this paper is to explore the possibility of siting an OTEC plant deep in the ocean and using it to drive a colocated Sea Water Reverse Osmosis Plant (SWRO). A thermodynamic analysis of this system is made to indicate the potential improvement in performance.as compared to conventional designs. Data on the performance and cost of conventional plants are used in conjunction with the thermodynamic analysis to give insight into potential advantages of the proposed scheme for the case where it is desired to produce desalinated water. Several advantages are shown to result from employment of this system as compared to conventional technologies including higher efficiency, lower cost, resistance to environmental damage, and improved aesthetics. It is concluded that the potential improvements from submerging an OTEC/SWRO plant, could lead to significant penetration of the technology for this niche situation.