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1. OTEC CYCLES – TYPES AND
WORKING
- DAANISH KAUSHAL
2020111016

2. O T E C
 A technology that converts solar radiation into usable power.
 Solar energy is absorbed by the largest collector of solar energy, i.e. the ocean
 Renewable energy generated using the natural thermocline – The natural temperature
gradient between the surface of the ocean and the water at depth of 800-1000m
 Thermocline of atleast 20oC is required for the system to be viably efficient.

3.  The science behind the thermocline is based on the Lambert’s Law of Absorption
–

4. WORKING PRINCIPLE
 The OTEC systems operate by using the
temperature gradient of the ocean to run a
Rankine Cycle –
 A low boiling point liquid refrigerant, such
as Ammonia is used as the working
medium for the cycle
 The working fluid is pumped through an
evaporator (heat exchanger) where the
heat from the surface water vaporizes the
liquid.
 The vapor is used to run a turbine, thereby
generating electricity
 The cold water at the depth of the ocean is
used to condense the vapor back to liquid
in the condenser (heat exchanger).

5. TYPES OF OTEC SYSTEMS
 There are 2 major types of OTEC systems that are available –
 CLOSED CYCLE
 OPEN CYCLE
 CLOSED: Makes use of low boiling working medium fluid such as NH3, Freon,
Propane etc. (Working fluid stays in closed loop)
 OPEN: Seawater itself serves all the roles – heat source, working medium, coolant
and heatsink.

6. CLOSED TYPE OTEC CYCLE
Resource(s): https://argonautes.club/the-indian-1-mw-floating-otec-plant.html

7. OPEN TYPE OTEC CYCLE

8. Flash evaporation is a distinguishing feature of open-cycle OTEC system.
Processes involved in open cycle OTEC are as follows –
1. The warm seawater is pumped into a chamber through spouts designed to
maximize the heat-and-mass-transfer surface area by producing a spray of the
liquid.
2. The pressure in the chamber (1% to 3% of atmospheric) is less than the saturation
pressure of the warm sea water.
3. Exposed to this low-pressure environment, water in the spray began to boil.
4. Dissolved gases in the water (O2, H2 etc.) are vacuumed out.
5. A separator is employed to split the water and the
6. The steam expands through a low-pressure turbine coupled with a generator that
produces electricity.
7. The exhaust steam is condensed back into liquid by cold deep seawater pumped
from the depth through a cold-water pipe.
Resource(s): https://gyansanchay.csjmu.ac.in/wp-content/uploads/2022/08/NCSOE-12.-OTEC.pdf

9. HOW DOES OTEC STAND OUT FROM
OTHER ENERGY SOURCES?
 Vastly available and self-renewing resource.
 Unlike a huge majority of fuels used today, there is virtually no emissions from
OTEC power generation.
 OTEC systems can operate continuously, providing a consistent and reliable source
of power that can meet the energy needs of large populations.
 This process yields a number of usable products, in addition to the power
generated, such as fresh, desalinated water etc.

10. ENERGY SCENARIO IN INDIA
 OTEC is said to have a potential capacity of 180GW for the 1.5x106 m2 of coastline
area available, as per studies from National Institute of Ocean Technology (NIOT).
 Indian government put strong emphasis on power generation by OTEC technology.
 India’s first ocean thermal energy conversion facility named “Sagar Shakti” has
been commissioned off the west coast of India.
 It has a capacity of 1 MW and is anchored off the Tuticorin Port.
 Other efforts include OTEC Cell set up by MoES(Ministry of Earth Sciences) for
R&D.
Resource(s): https://pib.gov.in/PressReleasePage.aspx?PRID=1582638