Ocean Thermal Energy Conversion is a renewable energy technology that uses the natural temperature difference of the ocean.

1. OCEAN
THERMAL
ENERGY
CONVERSION
Presented by:
B.A.T.M.Thilakarathne
SC/2016/9691

2. CONTENT
• Introduction
• Ocean
• Temperature of Ocean Water
• OTEC
• Sea water system
• Classification
• Cycle types
• Plant types
• Applications
• Advantages
• Disadvantages

3. INTRODUCTION

4. TEMPERATURE OF OCEAN WATER :
• There are 3 parts in ocean.
1. The surface layer.
2. Thermocline.
3. Deep ocean.
• The larger part of sunlight is
captured by ‘the surface layer’.
• Therefore the temperature of the
surface layer of ocean is higher
than deep ocean.
• So the deep ocean is the coldest.

5. • The stored solar energy in the ocean could be
converted into electrical power.
• The technology is called as Ocean Thermal
Energy Conversion(OTEC).
• The idea of tapping OTEC was first proposed by
French physicist ,Jacques Arsene d`Arsonal in
1881.
• The recent growth in interest in renewable energy,
development of OTEC has increased in the world.

6. OTEC(Ocean Thermal Energy Conversion)
OTEC is a renewable energy
technology that uses the natural
temperature difference in oceans to
produce electricity ,day and night
(OTEC is firm power (24/7)), year
around .

7. • With current technology, an annual temperature
difference of 20℃ or more is needed for OTEC.
• In order to produce power with the low temperature
range, a working fluid with low boiling point is used.
• Several countries are actively pursuing large-scale
deployment of OTEC.
• For example, companies and governments in France, Japan,
the Philippines and South Korea have developed roadmaps
for OTEC development.

8. • OTEC works on the principle of Rankine Cycle.

9. -Thermal resource region for OTEC-
• Tropical and equatorial zone are the interesting
areas for OTEC. Because of the highest
temperature difference.

10. Sea Water System
Warm water intake:-
• Depth - *For pilot plants will be about 10 m deep.
*For larger commercial plants will be about 20 m
deep.
• Shape and orientation - The intake structure is
constructed to produce
horizontal flows external to the
structure.

11. Cold water intake:-
• Depth -
• Shape and orientation - An open-ended pipe with
bar screens placed to
keep out relatively
large objects.
For most OTEC designs will be at a
depth of 750-1000m.

12. Used to vaporize a
working fluid with a low
boiling point (ammonia or
halocarbon Refrigerants).
Used to condense the
vapor and ensure the
vapor pressure difference
drives the turbine.
The warm
water
The cold water

13. CLASSIFICATION
According to cycle
type :-
• Open Cycle.
• Close Cycle.
• Hybrid Cycle.
According to location:-
• Land based plant.
• Off-Shore plant.

14. CYCLE TYPES

15. 1.Close Cycle
• Low boiling point working fluid is used (e.g. ammonia).
• The working fluid is evaporated by warm seawater.
• The expanding gas drives a gas turbine, is then re-condensed by
cold seawater, and the process is repeated.

16. Surface
layer
Deep
Ocean
Liquid
Ammoni
a
Vapor
Ammoni
a
Heat
Turbines
moves to
generate
electricity
condensate
evaporation
-Closed-Cycle OTEC Flow

17. • Open-Cycle systems use vaporized sea water as
the working fluid.
• Warm sea water pumped into a vacuum chamber
where a small amount is evaporated into low
density stream that drives a low pressure turbine.
• The steam is condensed by cold water.
• Desalinated water is a byproduct.
2.Open Cycle

18. Surface
layer
Deep
Ocean
Desalinate
d water
vapor
(Saturate)
Turbines
moves
to
generate
electricity
Desalinated
water vapor
(Unsaturated)
Desalinated
water
-Open-Cycle OTEC Flow

19. • This system used both open and close cycle
systems methods.
• The warm water enters to the vacuum chamber
where it is evaporated into steam.(Similar to the
open cycle)
• The steam vaporizes the working fluid .(Similar to
the close cycle)
• The steam drives a turbine that produces electricity.
• The steam condenses within the heat exchange to
produce desalinated water.
3.Hybrid Cycle

20. Surface
layer
Deep
Ocean
Desalinated
water vapor
Vapor
Ammoni
a
Turbines
moves to
generate
electricity
evaporation
-Hybrid-Cycle OTEC Flow
Liquid
Ammoni
a
condensate
Desalinated
water
Heat

21. PLANT TYPES

22. • Basic considerations for plant design and location
include
• A stable environment for the system operation
• A constant source of both warm and cold
water with a minimum temperature difference
20℃.
• A cost –effective way to deliver power and
complementary products.

23. • Land-based OTEC plants are constructed on the shoreline
with four large hot and cold pipelines dipping down into
the sea:
• Hot water input.
• Hot water output.
• Cold-water input.
• Cold-water output.
• An onshore OTEC facility can produce
• Electricity.
• Fresh water.
• Hydrogen that can promote agriculture.
• Provides refrigeration.
1. Land based plant

25. • The offshore platform installation has
comparatively lower land use and impact.
• but requires grid cables to be installed to
land.
• has higher construction and maintenance
costs.
2. Offshore plant

27. • Electricity Production.
• Desalinated Water.
• Refrigeration and Air-Conditioning.
• Mineral Extraction.
Applications

28. • Helps in producing fuels such as hydrogen,
ammonia, and methanol.
• Produces base load electrical energy .
• Produces desalinated water for industrial,
agricultural, and residential uses .
• Is a resource for on-shore and near-shore Mari-
culture operations .
Advantages

29. • Provides air-conditioning for buildings .
• Food Aquaculture products can be cultivated in
discharge water.
• Eco- friendly .
• Minimal maintenance costs compared to other
power production plants.

30. • High installation cost.
• It only had been tested in a very small scale.
• OTEC plant construction and operation may affect commercial
and recreational fishing.
• Other risks associated with the OTEC power system are the
safety issues associated with steam electric power generation
plants. Such as : -
Electrical hazards,
Rotating machinery,
Use of compressed gases,
Heavy material-handling equipment.
Disadvantages

31. • Irena.org, 2021. [Online]. Available: https://www.irena.org/-
/media/Files/IRENA/Agency/Publication/2014/Ocean_Thermal_Energy_V4_web.pdf.
References

32. Thank You!