Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that uses the temperature difference between warm surface water and deep ocean cold water to power a Rankine cycle and generate electricity. OTEC International LLC’s design uses a closed-cycle where liquid ammonia is vaporized in a heat exchanger fueled by the warm surface water. The vapor powers turbines that turn generators to produce electricity. The ammonia is cooled back to liquid state using the deep-ocean cold water and the process begins again.
Because the cold ocean water has become warmer in the process, it is discharged at a shallow depth, in water of a similar thermal layer.
The OTI design employs a combination of commercially available turbines, generators, pumps, motors/drives, couplings, valves and actuators, all with pedigrees for performance and reliability. Overall system performance is further enhanced by integration of proprietary heat exchangers in a floating platform exploiting principles of nature.
OTEC plants can operate anywhere that large volumes of water are available with average temperature differences of approximately 40 degrees F. This includes a wide band of locations around the world from approximately 20 degrees north to 20 degrees south of the equator. For off-shore connection to a land-based grid, access to cold water at depths of 1000 to 14000 meters within 30 miles of the interconnection point is preferable.
The process is energy intensive, so it is the net gain of power—that is, what is produced above the needs to produce it—that is the critical factor. Once this net gain is achieved, the cost to produce OTEC becomes competitive. There’s no fuel cost, just operating costs. Building an OTEC plant is capital intensive, and the OTI Technical Team is constantly applying best-value engineering practices to design, planning, manufacturing, operations, logistics and decommissioning – the entire life cycle.