report seminar 2
DESCRIPTION
MechanicalTRANSCRIPT
I
A
Seminar Report
On
OCEAN THERMAL ENERGY CONVERSION (OTEC)
Presented By
VIVEK DAYANAND PRASAD
Exam seat no. 120520902
T.E (MECHANICAL)
Guided By
Prof. P.V. Chopade
Mechanical Engineering Department
Indira College of Engineering & Management,
Pune – 410506
[2014-15]
II
Shree Chanakya Education Society’s
Indira College of Engineering &
Management, Pune.
C E R T I F I C A T E
This is to certify that Vivek Dayanand Prasad (T120520902) has successfully
completed the Seminar work entitled “Ocean Thermal Energy Conversion” in
the partial fulfillment of T.E. (Mechanical) for University of Pune.
Prof. P.V. Chopade Dr. Milind .K.Landge Prof. S. B.Ingole
Guide TE Coordinator HOD, Mechanical
External Examiner Date: Seal
Place:
III
ACKNOWLEDGEMENT
With immense pleasure, I am presenting this project report as a part of the curriculum
of T.E .(Mechanical). I wish to thank all the people who gave me endless support right from
the stage the idea was conceived.
I would like to thank Prof.Sunil Ingole (HOD, Mechanical Department), & Prof.
Milind Landage (TE Coordinator) for giving me opportunity to deliver a seminar on this
interesting topic.
I am heartily thankful to Prof. P.V. Chopade whose encouragement, guidance and
support from the initial to the final level enabled me to develop an understanding of the
subject. This seminar would not be possible without help of our internet department &
library department who helped me gathering the information from various sources.
Lastly, I offer my regards and blessings to all of those who supported me in any
respect during the completion of the project.
VIVEK D. PRASAD
T.E. (MECHANICAL)
Exam Seat no. T120520902
IV
ABSTRACT
Ocean Thermal Energy Conversion (OTEC) 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, with
little impact on the surrounding environment.
The distinctive feature of OTEC energy systems is that the end products include not
only energy in the form of electricity, but several other synergistic products. The principle
design objective was to minimize plan cost by minimizing plant mass, and taking maximum
advantage of minimal warm and cold water flows. Power is converted to high voltage DC,
and is cabled to shore for conversion to AC and integration into the local power distribution
network.
OTEC utilizes the temperature difference that exists between deep and shallow waters —
within 20° of the equator in the tropics — to run a heat engine. Because the oceans are
continually heated by the sun and cover nearly 70% of the Earth's surface, this temperature
difference contains a vast amount of solar energy which could potentially be tapped for
human use. The oceans are thus a vast renewable energy resource, with the potential to help
us produce billions of watts of electric power.
V
TABLE OF CONTENT
1 INTRODUCTION.............................................................................................................................1
1.1 Basics:....................................................................................................................................1
1.1.1 Thermal Energy Conversion:..........................................................................................2
1.2 Background and History of OTEC Technology........................................................................3
2 TYPES OF ENERGY CONVERSION SYSTEM......................................................................................6
2.1 Closed-cycle...........................................................................................................................6
2.2 Open-cycle.............................................................................................................................7
2.3 Hybrid cycle...........................................................................................................................8
3 OTEC PLANT DESIGN AND LOCATION............................................................................................9
3.1 Land-Based and Near-Shore Facilities....................................................................................9
3.2 Shelf-Mounted Facilities......................................................................................................10
3.3 Floating Facilities.................................................................................................................11
4 COMPARITIVE ANALYSIS..............................................................................................................12
4.1 Advantages..........................................................................................................................12
4.2 Disadvantages......................................................................................................................13
5 OTHER APPLICATIONS..................................................................................................................14
6 CASE STUDY: (INDIA)....................................................................................................................16
7 CONCLUSION...............................................................................................................................17
BIBLIOGRAPHY.....................................................................................................................................18
VI
LIST OF FIGURES
Figure 1-1 Seebeck Effect..........................................................................................................8
Figure 1-2 Peltier Effect.............................................................................................................8
Figure 1-3 Joulean Effect...........................................................................................................9
Figure 1-4 Thomson Effect........................................................................................................9
Figure 3-1 A Thermoelectric Refrigerator...............................................................................14
Figure 4-1 Schematic of Thermoelectric Cooler......................................................................16
Figure 4-2 The Combined TE-Direct Evaporative Air Cooler................................................17
Figure 4-3 Schematic of Thermoelectric Refrigerator.............................................................18
Figure 4-4 Schematic of Solar Cells driven Thermoelectric Refrigerator...............................19
Figure 4-5 Different location of TE generator in Refrigerator................................................20
Figure 4-6 TPM & TSF............................................................................................................21
LIST OF TABLES
(Eliminate this if there are no graphs)
LIST OF GRAPHS
(Eliminate this if there are no graphs)
Ocean Thermal Energy Conversion (OTEC)
1 INTRODUCTION
Oceans cover more than 70% of Earth's surface, making them the world's largest solar
collectors. The sun's heat warms the surface water a lot more than the deep ocean water, and
this temperature difference creates thermal energy. Just a small portion of the heat trapped in
the ocean could power the world.
1.1 Basics:
Most people have been witness to the awesome power of the world's oceans. For least
a thousand years, scientists and inventors have watched ocean waves explode against coastal
shores, felt the pull of ocean tides, and dreamed of harnessing these forces. But it's only been
in the last century that scientists and engineers have begun to look at capturing ocean energy
to make electricity.
Figure 1.1.1
The ocean can produce two types of energy: thermal energy from the sun's heat, and
mechanical energy from the tides and waves. Ocean thermal energy is used for many
applications, including electricity generation. Ocean mechanical energy is quite different
from ocean thermal energy. Even though the sun affects all ocean activity, tides are driven
primarily by the gravitational pull of the moon, and waves are driven primarily by the winds.
As a result, tides and waves are sporadic sources of energy, while ocean thermal energy is
fairly constant. Also, unlike thermal energy, the electricity conversion of both tidal and wave
energy usually involves mechanical devices.
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Ocean Thermal Energy Conversion (OTEC)
1.1.1 Thermal Energy Conversion:
OTEC is a process which utilizes the heat energy stored in the tropical ocean. The
world's oceans serve as a huge collector of heat energy. OTEC plants utilize the difference in
temperature between warm surface sea water and cold deep sea water to produce electricity.
Intensive Energy
The energy associated with OTEC derives from the difference in temperature between two
thermal reservoirs. The top layer of the ocean is warmed by the sun to temperatures up to
20 K greater than the seawater near the bottom of the ocean. OTEC energy is different from
geothermal energy in that one cannot assume the cold reservoir is infinite. The physical
energy of two large reservoirs of fluid at different temperatures is
Equation 1.1
in J/kg where r is the mass of warm water divided by the mass of cold water entering the
plant(1). For optimal performance, r is approximately 0.5. It is assumed in this analysis that
the specific heat of the two fluid reservoirs is an average value over the often small
temperature difference, but varying with salinity in the case of seawater.
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, an OTEC system can produce a significant amount of power. The oceans are
thus a vast renewable resource, with the potential to help us produce billions of watts of
electric power. This potential is estimated to be about 1013 watts of base load power
generation, according to some experts. The cold, deep seawater used in the OTEC process is
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Ocean Thermal Energy Conversion (OTEC)
also rich in nutrients, and it can be used to culture both marine organisms and plant life near
the shore or on land. OTEC produce steady, base-load electricity, fresh water, and air-
conditioning options.
Figure 1.1.2
OTEC requires a temperature difference of about 36 deg F (20 deg C). This
temperature difference exists between the surface and deep seawater year round throughout
the tropical regions of the world. To produce electricity, we either use a working fluid with a
low boiling point (e.g. ammonia) or warm surface sea water, or turn it to vapor by heating it
up with warm sea water (ammonia) or de-pressurizing warm seawater. The pressure of the
expanding vapor turns a turbine and produces electricity.
1.2 Background and History of OTEC Technology
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. In 1935, Claude constructed another
open-cycle plant, this time aboard a 10,000-ton cargo vessel moored off the coast of Brazil.
But both plants were destroyed by weather and waves, and Claude never achieved his goal of
producing net power (the remainder after subtracting power needed to run the system) from
an open-cycle OTEC system.
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Ocean Thermal Energy Conversion (OTEC)
Then in 1956, French researchers designed a 3-megawatt (electric) (MWe) open-cycle
plant for Abidjan on Africa's west coast. But the plant was never completed because of
competition with inexpensive hydroelectric power. In 1974 the Natural Energy Laboratory of
Hawaii (NELHA, formerly NELH), at Keahole Point on the Kona coast of the island of
Hawaii, was established. It has become the world's foremost laboratory and test facility for
OTEC technologies.
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 kilometers off Keahole Point. The plant used a cold-
water pipe to produce 52 kWe of gross power and 15 kWe net power.
In 1980, the U.S. Department of Energy (DOE) built OTEC-1, a test site for closed-
cycle OTEC heat exchangers installed on board a converted U.S. Navy tanker. Test results
identified methods for designing commercial-scale heat exchangers and demonstrated that
OTEC systems can operate from slowly moving ships with little effect on the marine
environment. A new design for suspended cold-water pipes was validated at that test site.
Also in 1980, two laws were enacted to promote the commercial development of OTEC
technology: the Ocean Thermal Energy Conversion Act, Public Law (PL) 96-320, later
modified by PL 98-623, and the Ocean Thermal Energy Conversion Research, Development,
and Demonstration Act, PL 96-310.
At Hawaii's Seacoast Test Facility, which was established as a joint project of the
State of Hawaii and DOE, desalinated water was produced by using the open-cycle process.
And a 1-meter-diameter col seawater/0.7-meter-diameter warm-seawater supply system was
deployed at the Seacoast Test Facility to demonstrate how large polyethylene cold-water
pipes can be used in an OTEC system.
In 1981, Japan demonstrated a shore-based, 100-kWe closed-cycle plant in the
Republic of Nauru in the Pacific Ocean. This plant employed cold-water pipe laid on the sea
bed to a depth of 580 meters. Freon was the working fluid, and a titanium shell-and-tube heat
exchanger was used. The plant surpassed engineering expectations by producing 31.5 kWe of
net power during continuous operating tests.
Later, tests by the U.S. DOE determined that aluminum alloy can be used in place of
more expensive titanium to make large heat exchangers for OTEC systems. And at-sea tests
by DOE demonstrated that biofouling and corrosion of heat exchangers can be controlled.
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Ocean Thermal Energy Conversion (OTEC)
Biofouling does not appear to be a problem in cold seawater systems. In warm seawater
systems, it can be controlled with a small amount of intermittent chlorination (70 parts per
billion per hour per day).
In 1984, scientists at a DOE national laboratory, the Solar Energy Research Institute
(SERI, now the National Renewable Energy Laboratory), developed a vertical-spout
evaporator to convert warm seawater into low-pressure steam for open-cycle plants. Energy
conversion efficiencies as high as 97% were achieved. Direct-contact condensers using
advanced packings were also shown to be an efficient way to dispose of steam. Using
freshwater, SERI staff developed and tested direct-contact condensers for open-cycle OTEC
plants.
British researchers, meanwhile, have designed and tested aluminum heat exchangers
that could reduce heat exchanger costs to $1500 per installed kilowatt capacity. And the
concept for a low-cost soft seawater pipe was developed and patented. Such a pipe could
make size limitations unnecessary, as well as improve the economics of OTEC systems.
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. Today, scientists are developing new, cost-
effective, state-of-the-art turbines for open-cycle OTEC systems.
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Ocean Thermal Energy Conversion (OTEC)
2 TYPES OF ENERGY CONVERSION SYSTEM
2.1 Closed-cycle
Closed-cycle systems use fluid with a low boiling point, such as ammonia, to rotate a
turbine to generate electricity. Warm surface seawater is pumped through a heat exchanger
where the low-boiling-point fluid is vaporized. The expanding vapor turns the turbo-
generator. Then, cold, deep seawater—pumped through a second heat exchanger—condenses
the vapor back into a liquid, which is then recycled through the system.
In 1979, the Natural Energy Laboratory and several private-sector partners developed
the mini OTEC experiment, which achieved the first successful at-sea production net
electrical power from closed-cycle OTEC. The mini OTEC vessel was moored 1.5 miles (2.4
km) off the Hawaiian coast and produced enough net electricity to illuminate the ship's light
bulbs, and run its computers and televisions.
Then, the Natural Energy Laboratory in 1999 tested a 250 kW pilot OTEC closed-
cycle plant, the largest such plant ever put into operation. Since then, there have been no tests
of OTEC technology in the United States, largely because the economics of energy
production today have delayed the financing of a permanent, continuously operating plant.
Outside the United States, the government of India has taken an active interest in OTEC
technology. India has built and plans to test a 1 MW closed-cycle, floating OTEC plant.
Figure 2.1.3
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Ocean Thermal Energy Conversion (OTEC)
2.2 Open-cycle
Open-cycle OTEC uses the tropical oceans' warm surface water to make electricity.
When warm seawater is placed in a low-pressure container, it boils. The expanding steam
drives a low-pressure turbine attached to an electrical generator. The steam, which has left its
salt behind in the low-pressure container, is almost pure fresh water.
2.2.4
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Ocean Thermal Energy Conversion (OTEC)
Figure 2.2.5
It is condensed back into a liquid by exposure to cold temperatures from deep-ocean
water.
In 1984, the Solar Energy Research Institute (now the National Renewable Energy
Laboratory) developed a vertical-spout evaporator to convert warm seawater into low-
pressure steam for open-cycle plants. Energy conversion efficiencies as high as 97% were
achieved for the seawater to steam conversion process (note: the overall efficiency of an
OTEC system using a vertical-spout evaporator would still only be a few per cent). 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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Ocean Thermal Energy Conversion (OTEC)
2.3 Hybrid cycle
Hybrid systems combine the features of both the closed-cycle and open-cycle
systems. In a hybrid system, warm seawater enters a vacuum chamber where it is flash-
evaporated into steam, similar to the open-cycle evaporation process. The steam vaporizes a
low-boiling-point fluid (in a closed-cycle loop) that drives a turbine to produce electricity.
2.3.6
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Ocean Thermal Energy Conversion (OTEC)
3 OTEC PLANT DESIGN AND LOCATION
Commercial ocean thermal energy conversion (OTEC) plants must be located in an
environment that is stable enough for efficient system operation. The temperature of the
warm surface seawater must differ about 20°C (36°F) from that of the cold deep water that is
no more than about 1000 meters (3280 feet) below the surface. The natural ocean thermal
gradient necessary for OTEC operation is generally found between latitudes 20 deg N and 20
deg S. Within this tropical zone are portions of two industrial nations—the United States and
Australia—as well as 29 territories and 66
developing nations. Of all these possible sites, tropical islands with growing power
requirements and a dependence on expensive imported oil are the most likely areas for OTEC
development.
Commercial OTEC facilities can be built on
* Land or near the shore
* Platforms attached to the shelf
* Moorings or free-floating facilities in deep ocean water.
3.1 Land-Based and Near-Shore Facilities
Land-based and near-shore facilities offer three main advantages over those located in
deep water. Plants constructed on or near land do not require sophisticated mooring, lengthy
power cables, or the more extensive maintenance associated with open-ocean environments.
They can be installed in sheltered areas so that they are relatively safe from storms and heavy
seas. Electricity, desalinated water, and cold, nutrient-rich seawater could be transmitted from
near-shore facilities via trestle bridges or causeways. In addition, land-based or near-shore
sites allow OTEC plants to operate with related industries such as mariculture or those that
require desalinated water.
Favored locations include those with narrow shelves (volcanic islands), steep (15-20
deg) offshore slopes, and relatively smooth sea floors. These sites minimize the length of the
cold-water intake pipe. A land-based plant could be built well inland from the shore, offering
more protection from storms, or on the beach, where the pipes would be shorter. In either
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Ocean Thermal Energy Conversion (OTEC)
case, easy access for construction and operation helps lower the cost of OTEC-generated
electricity.
Land-based or near-shore sites can also support mariculture. Mariculture tanks or
lagoons built on shore allow workers to monitor and control miniature marine environments.
Mariculture products can be delivered to market with relative ease via railroads or highways.
One disadvantage of land-based facilities arises from the turbulent wave action in the
surf zone. Unless the OTEC plant's water supply and discharge pipes are buried in protective
trenches, they will be subject to extreme stress during storms and prolonged periods of heavy
seas. Also, the mixed discharge of cold and warm seawater may need to be carried several
hundred meters offshore to reach the proper depth before it is released. This arrangement
requires additional expense in construction and maintenance.
OTEC systems can avoid some of the problems and expenses of operating in a surf
zone if they are built just offshore in waters ranging from 10 to 30 meters deep (Ocean
Thermal Corporation 1984). This type of plant would use shorter (and therefore less costly)
intake and discharge pipes, which would avoid the dangers of turbulent surf. The plant itself,
however, would require protection from the marine environment, such as breakwaters and
erosion-resistant foundations, and the plant output would need to be transmitted to shore.
3.2 Shelf-Mounted Facilities
OTEC plants can be mounted to the continental shelf at depths up to 100 meters.
A shelf-mounted plant could be built in a shipyard, towed to the site, and fixed to the sea
bottom. This type of construction is already used for offshore oil rigs. The additional
problems of operating an OTEC plant in deeper water, however, may make shelf-mounted
facilities less desirable and more expensive than their land-based counterparts. Problems with
shelf-mounted plants include the stress of open-ocean conditions and more difficult product
delivery. Having to consider strong ocean currents and large waves necessitates additional
engineering and construction expense.
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Ocean Thermal Energy Conversion (OTEC)
Platforms require extensive pilings to maintain a stable base for OTEC operation.
Power delivery could also become costly because of the long underwater cables required to
reach land. For these reasons, shelf-mounted plants are less attractive for near-term OTEC
development.
3.3 Floating Facilities
Floating OTEC facilities could be designed to operate off-shore. Although
potentially preferred for systems with a large power capacity, floating facilities present
several difficulties. This type of plant is more difficult to stabilize, and the difficulty of
mooring it in very deep water may create problems with power delivery. Cables attached to
floating platforms are more susceptible to damage, especially during storms. Cables at depths
greater than 1000 meters are difficult to maintain and repair.
Riser cables, which span the distance between the sea bed and the plant, need to be
constructed to resist entanglement. As with shelf-mounted plants, floating plants need a stable
base for continuous OTEC operation. Major storms and heavy seas can break the vertically
suspended cold-water pipe and interrupt the intake of warm water as well. To help prevent
these problems, pipes can be made of relatively flexible polyethylene attached to the bottom
of the platform and gimballed with joints or collars. Pipes may need to be uncoupled from the
plant to prevent damage during storms. As an alternative to having a warm-water pipe,
surface water can be drawn directly into the platform; however, it is necessary to locate the
intake carefully to prevent the intake flow from being interrupted during heavy seas when the
platform would heave up and down violently.
If a floating plant is to be connected to power delivery cables, it needs to remain
relatively stationary. Mooring is an acceptable method, but current mooring technology is
limited to depths of about 2000 meters (6560 feet). Even at shallower depths, the cost of
mooring may prohibit commercial OTEC ventures. An alternative to deep-water OTEC may
be drifting or self-propelled plantships. These ships use their net power on board to
manufacture energy-intensive products such as hydrogen, methanol, or ammonia (Francis,
Avery, and Dugger 1980).Electricity generated by plants fixed in one place can be delivered
directly to a utility grid. A submersed cable would be required to transmit electricity from an
anchored floating platform to land.
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Ocean Thermal Energy Conversion (OTEC)
4 COMPARITIVE ANALYSIS
The world population is 6.1 billion in 2000, and it is still growing explosively. At the same
time, energy consumed by human is also increasing explosively, as shown . By considering
future economic growth and environmental problems it is obvious that in the 21st century we
cannot rely on the current mainstream resources, i.e. oil, coal, and uranium for the world
energy supply. Thus, we must face the urgent and important problem of developing an
alternative energy source to fossil and nuclear fuel. For the alternative energy sources we can
easily consider, for example, such as wind, solar and geothermal power. However, ocean
energy should become also an important potential energy source which must be obtained.
4.1 Advantages
1. OTEC uses clean, renewable, natural resources. Warm surface seawater and
cold water from the ocean depths replace fossil fuels to produce electricity.
2. Suitably designed OTEC plants will produce little or no carbon dioxide or other
polluting chemicals.
3. OTEC systems can produce fresh water as well as electricity. This is a
significant advantage in island areas where fresh water is limited.
4. There is enough solar energy received and stored in the warm tropical ocean
surface layer to provide most, if not all, of present human energy needs.
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Ocean Thermal Energy Conversion (OTEC)
5. The use of OTEC as a source of electricity will help reduce the state's almost
complete dependence on imported fossil fuels.
4.2 Disadvantages
1.OTEC-produced electricity at present would cost more than electricity generated from
fossil fuels at their current costs. The electricity cost could be reduced significantly if the
plant operated without major overhaul for 30 years or more, but data on possible plant life
cycles is unavailable.
2. OTEC plants must be located where a difference of about 40° Fahrenheit (F) occurs year
round. Ocean depths must be available fairly close to shore-based facilities for economic
operation. Floating plant ships could provide more flexibility.
3. High capital cost and an overall lack of familiarity and research with OTEC technology.
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Ocean Thermal Energy Conversion (OTEC)
5 OTHER APPLICATIONS
OTEC systems are not just limited to just producing electricity and because of the unique
design of these power stations are potentially available to tackle other ventures in
combination with electricity to offset some of the expenses associates with OTEC.
A. Fresh water production
Desalination is just one of the effective potential products that could be produced via OTEC
technology. Fresh water can be produced in open-cycle OTEC plants when the warm water is
vaporized to turn the low pressure turbine. Once the electricity is produced the water vapor is
condensed to make fresh water (Takahashi and Trenka, 1996). This water has been found to
be purer then water offered by most communities as well it is estimated that 1 MW plant
could produce 55 kg of water per second. This rate of fresh water could supply a small
coastal community with approximately 4000 m3/day of fresh water (Takahashi and Trenka,
1996). This water can also be used for irrigation to improve the quality and quantity of food
on coastal regions especially where access to fresh water is scarce.
B. Air conditioning and Refrigeration
Once cold water pipes are installed for an OTEC power plant the cold water being pumped to
the surface can be used for other projects other then to provide the working fluid for the
condenser. One of these uses is air conditioning and refrigeration. Cold water can be used to
circulate through space heat exchangers or can be used to cool the working fluid within heat
exchangers (Takahashi and Trenka, 1996). This technology can be applied for hotel and
home air conditioning as well as for refrigeration schemes.
C. Aquaculture and Mariculture
Another possibility for taking advantage of OTEC plants is the use of the water pipes to
harvest marine plants and animals for the purpose of food. This proposition is still under
investigation however it is proposed that seawater life including salmon, abalone, American
lobster, flat fish, sea urchin and edible seaweeds could be harvested for ingestion using the
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Ocean Thermal Energy Conversion (OTEC)
cold water pipes that would be readily available from the OTEC power plants (Takahashi and
Trenka, 1996).
Mariculture is another possibility that is currently being researched that would take advantage
of the cold deep ocean water being transferred to the oceans surface. This water contains
phytoplankton and other biological nutrients that serve as a catalyst for fish and other aquatic
populations (Takahashi and Trenka,1996). This water could serve to increase native fish
populations through the recycling of trace nutrients
that would not be otherwise available.
D. Coldwater Agriculture
Because the coastal areas suitable for OTEC are in tropic regions there is a potential to
increase the overall food diversity within an area using the cold water originating from the
deep ocean. It has been proposed that burying a network of coldwater pipes underground the
temperature of the ground would be ideal for spring type crops like strawberries and other
plants restricted to cooler climates (Takahashi and Trenka, 1996). This would not only supply
the costal populations with an increased variety of food but reduce the cost of transport of
cooler climate foods that would otherwise have to be shipped.
Figure 4.2.7
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Ocean Thermal Energy Conversion (OTEC)
6 CASE STUDY: (INDIA)
Conceptual studies on OTEC plants for Kavaratti (Lakshadweep islands), in the
Andaman-Nicobar Islands and off the Tamil Nadu coast at Kulasekharapatnam were initiated
in 1980. In 1984 a preliminary design for a 1 MW (gross) closed Rankine Cycle floating
plant was prepared by the Indian Institute of Technology in Madras at the request of the
Ministry of Non-Conventional Energy Resources. The National Institute of Ocean
Technology (NIOT) was formed by the governmental Department of Ocean Development in
1993 and in 1997 the Government proposed the establishment of the 1 MW plant of earlier
studies. NIOT signed a memorandum of understanding with Saga University in Japan for the
joint development of the plant near the port of Tuticorin (Tamil Nadu).
It has been reported that following detailed specifications, global tenders were placed
at end-1998 for the design, manufacture, supply and commissioning of various sub-systems.
The objective is to demonstrate the OTEC plant for one year, after which it could be moved
to the Andaman & Nicobar Islands for power generation. NIOT’s plan is to build 10-25 MW
shore-mounted power plants in due course by scaling-up the 1 MW test plant, and possibly a
100 MW range of commercial plants thereafter.
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Ocean Thermal Energy Conversion (OTEC)
7 CONCLUSION
OTEC has tremendous potential to supply the world’s energy. It is estimated that, in
an annual basis, the amount solar energy absorbed by the oceans is equivalent to at least 4000
times the amount presently consumed by humans. For an OTEC efficiency of 3 percent, in
converting ocean thermal energy to electricity, we would need less than 1 percent of this
renewable energy to satisfy all of our desires for energy.
OTEC offers one of the most compassionate power production technologies, since the
handling of hazardous substances is limited to the working fluid (e.g., ammonia), and no
noxious by-products are generated. Through adequate planning and coordination with the
local community, recreational assets near an OTEC site may be enhanced. OTEC is capital-
intensive, and the very first plants will most probably be small requiring a substantial capital
investment. Given the relatively low cost of crude oil and of fossil fuels in general, the
development of OTEC technologies is likely to be promoted by government
agencies. Conventional power plants pollute the environment more than an OTEC plant
would and, as long as the sun heats the oceans, the fuel for OTEC is unlimited and free
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Ocean Thermal Energy Conversion (OTEC)
BIBLIOGRAPHY
x[1]Ocean Thermal Energy Conversion [Online]. www.wikipedia.org
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