This takes advantage of the fact that the ocean is an enormous heat engine. So, in principle any two reservoirs with different temperatures T1 and T2 can produce energy. There will be a demonstration of this principle in class today. In other words, all thermodynamic systems must tend towards equilibrium.
Some energy goes towards performing work and some is lost as waste heat.
Since heat differences in the ocean will be smaller, then one must substitute ammonia for water as the working fluid. Energy extracted proportional to the volume of water and the temperature it drops. Principal energy loss is when the warmer water meets the cooler water in the condenser. Thermal gradients of greater than 22 C can be exploited and used as a heat engine Energy is derived from cooling warm surface water to the temperature of the water at approximately 500-1000 feet depth. The ocean is a huge reservoir for storing the energy of the sun that is incident on the earth.