1-1. What is OTEC? OTEC is an innovational power generation system to generate electricity, using relatively small temperature difference (economically feasible over 15 degrees Celsius) between warm and cold seawater. In tropical areas, the average temperature of the ocean surface waters is more than 20 degrees Celsius whereas that of the deep waters is about 5 degrees Celsius; therefore, these areas are suitable for OTEC facilities all the year around. Fig 1. The area available for OTEC and the temperature difference