An offshore power generation structure comprising a submerged portion having a first deck portion comprising an integral multi-stage evaporator system, a second deck portion comprising an integral multi-stage condensing system, a third deck portion housing power generation equipment, cold water pipe; and a cold water pipe connection. The heat exchangers in the evaporator and condenser systems include a multi-stage cascading heat exchange system. Warm water conduits in the first deck portion and cold water conduits in the second deck portion are integral to the structure of the submerged portion of the offshore platform.