Why does an open-cycle OTEC use low-pressure container?

Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that uses the temperature difference between the ocean's surface and deep water to generate electricity. The heat from the surface water and the cold from the deep water drive a Rankine Cycle, which produces electricity.  OTEC plants pump large amounts of deep, cold seawater and surface seawater to run a power cycle. The cooled warm water and the warmed cold water are then discharged back into the ocean.  OTEC can also be used to provide cold water for building air-conditioning systems, which can result in energy... Show more

Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that uses the temperature difference between the ocean's surface and deep water to generate electricity. The heat from the surface water and the cold from the deep water drive a Rankine Cycle, which produces electricity. 

OTEC plants pump large amounts of deep, cold seawater and surface seawater to run a power cycle. The cooled warm water and the warmed cold water are then discharged back into the ocean. 
OTEC can also be used to provide cold water for building air-conditioning systems, which can result in energy savings of up to 90%. 

There are three types of OTEC systems: closed-cycle, open-cycle, and hybrid. 

Some environmental concerns about OTEC are:
- Impacts on marine life
- Intake of warm water from the ocean can impact marine life, particularly in shallow waters.
- Potential for oil spills: OTEC plants that use oil as a working fluid could release oil into the environment in the event of a spill. 
 

Related:

Renewable Energy Practice Test: Geothermal Energy & Applications 

Renewable Energy Practice Test: Tidal Energy

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