2. CONTENTS
INTRODUCTION
HISTORY OF OTEC
TYPES OF OTEC PLANTS
ACHIEVEMENTS IN OTEC
SCHEMATIC REPRESENTATION OF OTEC PLANT
APPLICATION OF OTEC
BENEFITS OF OTEC
LIMITATION OF OTEC
CONCLUSION
REFERRENCES
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3. INTRODUCTION
OTEC, or ocean thermal energy conversion, is an energy technology that converts solar radiation
to electric power. OTEC systems use the ocean's natural thermal gradient—the fact that the
ocean's layers of water have different temperatures—to drive a power-producing cycle
As long as the temperature between the warm surface water and the cold deep water differs by
about 20°C (36°F), an OTEC system can produce a significant amount of power.
The cold, deep seawater used in the OTEC process is also rich in nutrients, and it can be used to
culture both marine organisms and plant life near the shore or on land.
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4. INTRODUCTION
The oceans cover a little more than 70 percent of the Earth's surface. This makes them the
world's largest solar energy collector and energy storage system.
On an average day, 60 million square kilometres (23 million square miles) of tropical seas absorb
an amount of solar radiation equal in heat content to about 250 billion barrels of oil.
This potential is estimated to be about 10 raised to power 13 watts of power generation,
according to some experts.
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6. TYPES OF OTEC PLANT
OTEC Plants are primarily of three types
Land based plants or onshore plants
Shelf based plants
Floating type plants
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7. TYPES OF OTEC PLANT
LAND BASED PLANT
In this types of plant the OTEC plant is located on an onshore site while it draws water from an
ocean or sea through pumps and water is transported through pipes.
This type of plant offers the following advantage-
They can be installed in sheltered area so they can be saved during storm and other harsh
condition
It does not require sophisticated mooring, or lengthy power cables
It can be located close to industries such as Mari culture or those that require desalinated water.
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9. TYPES OF OTEC PLANT
SHELF BASED PLANT
OTEC plants can be mounted to the continental shelf at depths up to 100 meters (330 ft). A shelf-
mounted plant could be towed to the site and affixed to the sea bottom.
The advantage of such plant is that is located close to hot as well as cold source of water so it can
be more effective in power generation
Such plant can also be build along with other facilities such as research centres in ocean for
variety of applications
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11. TYPES OF OTEC PLANT
FLOATING PLANT
Floating type OTEC plant operate off shore. This type of plant are primal for large system and are
ideal for pilot plants.
The main advantages of such plant is that it can be easy installed and the required research for
setting up a permanent plant as well as for research projects can bed done
The disadvantage of such plant is that it is more prone to damages due to storms .The process of
laying powerlines at greater depth is yet another disadvantage
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13. HISTORY OF OTEC
In 1881, Jacques Arsene d'Arsonval, a French physicist, was the first to propose tapping the
thermal energy of the ocean.
Georges Claude, a student of d'Arsonval's, built an experimental open-cycle OTEC system at
Matanzas Bay, Cuba, in 1930. The system produced 22 kilowatts (kW) of electricity by using a
low-pressure turbine.
Then in 1956, French researchers designed a 3-megawatt (electric) (MWe) open-cycle plant for
Abidjan on Africa's west coast
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14. ACHIEVEMENTS IN OTEC
In 1979, the first 50-kilowatt (electric) (kWe) closed-cycle OTEC demonstration plant went up at
NELHA. Known as "Mini-OTEC," the plant was mounted on a converted U.S. Navy barge moored
approximately 2 kilometres off Keahole Point.
In 1981, Japan demonstrated a shore-based, 100-kWe closed-cycle plant in the Republic of
Nauru in the Pacific Ocean. The plant surpassed engineering expectations by producing 31.5
kWe of net power during continuous operating tests.
In May 1993, an open-cycle OTEC plant at Keahole Point, Hawaii, produced 50,000 watts of
electricity during a net power-producing experiment. This broke the record of 40,000 watts set
by a Japanese system in 1982.
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16. APPLICATIONS OF OTEC
The various applications of OTEC are-
Power Generation
Refrigeration & Air Conditioning of offshore and onshore structures
Desalinating water
Artificial Fishing
Mineral Exploration
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18. POWER GENERATION
Two main methods are used for power generation they are –
Closed Cycle Method
Open Cycle Method
Hybrid cycle Method
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19. POWER GENERATION USING
CLOSED CYCLE METHOD
In the closed-cycle OTEC system, warm seawater vaporizes a working fluid, such as ammonia, flowing
through a heat exchanger (evaporator).
The steam of ammonia is utilized to run a turbine to generate power
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21. POWER GENERATION USING OPEN
CYCLE
In an open-cycle OTEC system, warm seawater is the working fluid. The warm seawater is "flash"-
evaporated in a vacuum chamber to produce steam at an absolute pressure of about 2.4
kilopascals (kPa).
This is used to run turbine to generate power
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23. POWER GENERATION USING
HYBRID SYSTEM
A hybrid cycle combines the features of both the closed-cycle and open-cycle systems.
In a hybrid OTEC system, warm seawater enters a vacuum chamber where it is flash-evaporated
into steam, which is similar to the open-cycle evaporation process
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25. APPLICATION IN AIR
CONDITIONING AND MINOR
REFRIGERATION
The cold seawater delivered to an OTEC plant can be used in chilled-water coils to provide air
conditioning for both offshore and on shore projects and structure.
The cold water of the ocean can be used as an exchanger medium for HVAC as well as minor
refrigeration
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27. DESALINATING WATER
Desalinated water can be produced in open- or hybrid-cycle plants using surface condensers.
In a surface condenser, the spent steam is condensed by indirect contact with the cold seawater.
This condensate is relatively free of impurities and can be collected and sold to local communities
where natural freshwater supplies for agriculture or drinking are limited
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28. ARTIFICIAL FISHING
The cold [5°C (41ºF)] seawater made available by an OTEC system creates an opportunity to
provide large amounts of cooling to operations that are related to or close to the plant.
Salmon, lobster, abalone, trout, oysters, and clams are not indigenous to tropical waters, but they
can be raised in pools created by OTEC-pumped water
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29. MINERAL EXPLORATION
OTEC could provide to mine ocean water for its 57 elements dissolved in solution.
In the past, most economic analyses showed that mining the ocean for trace elements dissolved
in solution would be unprofitable because so much energy is required to pump the large volume
of water needed and because it is so expensive to separate the minerals from seawater.
However, because OTEC plants will already be pumping the water economically, the only problem
to solve is the cost of the extraction process
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30. BENEFITS OF OTEC
It is totally a non polluting form of energy
It can help reduce our dependence on fossil fuels
It can help produce desalinated water from sea water
It can help improve quality and variety of sea food in market
It is a great source of energy and power for offshore and near shore operation
It is a great source power for exploration and related activities in the sea
Unlike other forms of solar energy the energy from sea shows little daily variation
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31. LIMITATION OF OTEC
The site of OTEC are limited
The initial cost of setting up a project is quite high
The maintenance cost of such project is high since the components are subjected to a large
amount to destructive forces of nature
Low efficiency along with large investment makes the projects uneconomical
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32. CONCLUSION
The technology is a great one to satisfy the ever increasing need for energy for the present as
well as for the future generation and also a non polluting one.
If proper research and development is carried on in this field we can satisfactorily fulfil the needs
of the people and reduce our dependence on fossil fuels which contributes to large part of our
energy requirement but is bound to be exhausted in a few years.
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