· Ocean Thermal Energy Conversion
· Uses the difference between cooler deep and warmer shallow or surface ocean waters to run a heat engine and produce useful work, usually in the form of electricity.
· Locations:
o On land, shelf, free-floating
§ On land
· Longer cold-water intake
§ On shore
· Reduces cold water intake
§ Shelf mounted
· Fixed to seafloor
o Out of turbulent surf zones
o Closer to cold water resources (more challenging delivery?)
· Open Cycle:
o Utilizes warm (surface) water to make electricity
o It is put into a low pressure container where it boils
o Expanding water vapor is used to drive a low-pressure turbine
o Salt of the water remains in the low pressure container
o Turbine is attached to an electrical generator
o Cold sea water is then used to condense the steam back into a liquid
o The air that is released from the water (incondensable) are then compressed to a pressure necessary to remove it from the system
· Closed Cycle
o Can be modeled as a saturated Rankine Cycle
o Unlike open-cycle systems, which use warm water to make electricity, closed-cycle systems utilize ammonia
§ Ammonia is attractive for its low boiling point
§ Other fluids with similarly low boiling points can be used as well
o Warm (surface) water is pumped through a heat exchanger
§ Here, the ammonia is vaporized
§ Expanding vapor is then used to turn a turbo-generator
o Cold (deep) water is then pumped into the system
§ This water is used to condense the vapor back into a liquid to be recycled
· Cons:
o Expensive
o Low Efficiency – 2-2.5% Electrical efficiency
o Biofouling- the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures. | 
