OTEC runs on warm and cold sea-water instead of burning a fuel.
OTEC can only work in the Tropics because it is there that the largest natural temperature differences can be found.
The quoted minimum temperature difference required is 20 degrees but a little less could be possible.
The warmer the surface water and the colder the deep water the better the system can run per unit of water pumped.
The cold water must be taken from 750-1000 meters below the sea-surface if the system is to work ‘naturally”.
OTEC requires around 2.5 litres per second of deep-sea-cold-water to produce around 1 kw of electricity.