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BETA NUR PRATIWIM0211012)
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What is OTEC ?OTEC ocean thermal energy conversion) :sistem konversi energi panas laut menjadi energi listrik.
FUNDAMENTALS 75% of the Earth Covered by water
Ocean water stores much more heat than theatmosphere
(Jackie Rowley)
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Lockheed Martin
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History 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 anexperimental open-cycle OTEC system at Matanzas Bay, Cuba,in 1930. The system produced 22 kilowatts (kW) of electricityby using a low-pressure turbine. In 1935, Claude constructedanother open-cycle plant, this time aboard a 10,000-ton cargovessel moored off the coast of Brazil. But both plants weredestroyed by weather and waves, and Claude never achievedhis goal of producing net power (the remainder aftersubtracting power needed to run the system) from an open-cycle OTEC system.
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 competitionwith inexpensive hydroelectric power.
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History Contd
1979: The first 50-kilowatt ( (kWe)
closed-cycle OTEC demonstrationplant went up at NELHA.
Known as "Mini-OTEC," the plantwas mounted on a converted U.S.Navy barge moored approximately 2kilometers off Keahole Point. The
plant used a cold-water pipe toproduce 52 kWe of gross power and15 kWe net power.
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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, experimentingwith anti corroding Titanium and plastics as rotor material.
The new designs for OTEC are still mostly experimental. Onlysmall-scale versions have been made. The largest so far is nearJapan, and it can create 100 kilowatts of electricity.
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OTEC Description
Oceanic Thermal Energy Conversion
OTEC utilizes the oceans 20C natural thermal gradiebetween the warm surface water and the cold deep sea watto drive a Rankine Cycle
OTEC utilizes the worlds largest solar radiation collectorthe ocean. The ocean contains enough energy power all the worldselectrical needs.
12/18/2009 8OTEC African Deployment
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OTEC System P-Diagram
OTEC
System
ControlsWater Pump
Fluid Pump
OTEC CPU
Turbine
Generator
Heat Exchangers
Pipes
Working fluid
(Noise Factors)
Temperature
Sea state
Weather
Corrosion
(Output Functions)
Power
Water
(Input Signals)
Water
Startup Power
9OTEC African Deployment
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Operational Concept
System Boundary
Power PlanControl
SystemWarm Seawater isExternal Input
Cold Seawater is
External Input
Power
Plant
O
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Open-Cycle
Open-cycle OTEC uses the tropical oceans' warm surfacewater to make electricity. When warm seawater is placed in alow-pressure container, it boils. The expanding steam drives alow-pressure turbine attached to an electrical generator. Thesteam, which has left its salt behind in the low-pressurecontainer, is almost pure fresh water. It is condensed backinto a liquid by exposure to cold temperatures from deep-ocean water.
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Closed-Cycle (Rankine)
Closed-cycle systems use fluid with a low-boiling point, suchammonia, to rotate a turbine to generate electricity. Here's hoit works. Warm surface seawater is pumped through a heexchanger where the low-boiling-point fluid is vaporized. Texpanding vapor turns the turbo-generator. Then, cold, deseawaterpumped through a second heat exchangercondenses the vapor back into a liquid, which is then recyclthrough the system.
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Laju amonia menguap(kg/s)
h:entalphi
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Hybrid SystemHybrid systems combine the features of both the closed-cycleand open-cycle systems. In a hybrid system, warm seawaterenters a vacuum chamber where it is flash-evaporated into
steam, similar to the open-cycle evaporation process. Thesteam vaporizes a low-boiling-point fluid (in a closed-cycleloop) that drives a turbine to produces electricity.
Ammonia is the working flu
Warm sea water is flashed is then used to vaporammonia
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MAIN COMPONENTS OF AN OTEC SYSTEM Evaporators
Condensers
Cold-water pipe
Turbines
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HEAT EXCHANGERS
In an advanced plate-and-fin design,working fluid and seawater flowthrough alternating parallel plates; finsbetween the plates enhance the heattransfer
Original material chosen Titanium -Expensive, so alternative material Aluminium.
Selected Aluminium alloys may last 20years in seawater.
Characterized by low pressure ratios and high mass flow of working fluidsThe turbine is to be designed to have a good isentropic expansion efficover a considerable range of pressure ratio
TURBINES
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Otec production of electricity
Nomi
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ECONOMIC CONSIDERATIONS
OTEC needs high investmentEfficiency only 3% - low energy density large heat transfer equipment
therefore more cost
F b id d hil h i i
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Factors to be considered while choosing a site:
Thermal gradient in the ocean
Topography of the ocean floor
Meteorological conditions hurricanes
Seismic activity Availability of personnel to operate the plant
Infrastructure airports, harbors, etcilabilityof shoreline sites
Offshore
Distance,
km
Capital
Cost, $/kW
10 4200
50 5000
100 6000
200 8100
300 10200
400 12300
Cost Estimates for 100 MW CC-OTEC Plantship(COE for 10 % Fixed Rate, 20 years, Annual Operation & Maintenance 1
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POTENTIALEquatorial, tropical and sub-tropical regions i.e.
20 N to 20 S, have favorable temperature profile Total estimated potential 577000 MW 99 nations and territories have access to the
OTEC thermal resource:
AmericasMainland - 15AmericasIsland - 23AfricaMainland - 18AfricaIsland - 5Indian/Pacific OceanMainland - 11Indian/Pacific OceanIsland - 27
Countries with access to deep ocean water withshore and favorable business climate:
AmericasMainland - 1, Mexico
AmericasIsland - 12
AfricaMainland - 1, Tanzania
AfricaIsland - 1, Madagascar
Indian/Pacific OceanMainland - 1, India
Indian/Pacific OceanIsland
E i t l A t
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Environmental Aspects
Positives:
Environmentally benign - no toxic products are released
Carbon di oxide emission - less than 1% of fossil fuel plant
Nutrient rich coldwaterpromotes mariculture
Chilled soil agriculture promotes growth of temperatecrops in tropical regions.
Cold water for air conditioning
Fresh water production (1 MW plant -> 4500 m3)
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Promotes mariculture
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Environmental Aspects
Negatives:
Fish eggs and larvae entrained, destroyed Sterilization of land by land based plants
Floating plants navigational hazard
Metal pieces entrained affects marine orgs.
Mixing of warm and cold sea water
OTEC is yet untested on large scale over a long period of
time
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Records available from experimental plants demonstrtechnical viability and provide invaluable data on toperation of OTEC plants. The economic evaluation OTEC plants indicates that their commercial future liesfloating plants of approximately 100 MW capacity industrialized nations and smaller plants for small-islandeveloping-states
Small OC-OTEC plants can be sized to produce from 1 Mto 10 MW of electricity, and at least 1700 m3to 3500 m3
desalinated water per day.
The Future
O C &
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210kW OC-OTEC Experimental Plant (1993-1998) in Hawaii
OTEC R&D
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Prospek di IndonesiaUntuk lautan di wilayah Indonesia, potensi termal 2,5 x 1023 joule
dengan efisiensi konversi energi panas laut sebesar tiga persen dapat
menghasilkan daya sekitar 240.000 MW. Potensi energi panas lautyang baik terletak pada daerah antara 6- 9lintang selatan dan 104-
109bujur timur. Di daerah tersebut pada jarak kurang dari 20 km
dari pantai didapatkan suhu rata-rata permukaan laut di atas 28C
dan didapatkan perbedaan suhu permukaan dan kedalaman laut
(1.000 m) sebesar 22,8C. Sedangkan perbedaan suhu rata-rata
tahunan permukaan dan kedalaman lautan (650 m) lebih tinggi dari
20C. Konversi energi panas laut dapat dijadikan alternatif
pemenuhan kebutuhan energi listrik di Indonesia.
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Resources http://www.otecnews.org/
http://www.hawaii.gov/dbedt/ert/otec/index.html
http://www.ocees.com/mainpages/qanda.html#faq3 Pierre Cannon Sumon Nandy Amy Nandy
PRABUDDHA BANSAL ARAVIND G NAVANEETHA KRISHNAN N SHASHANK NARAYAN Finney, Karen Anne.2008.. Guelph Engineering Journal, Ocean Thermal Energy Conversion
(1), 17 - 23. ISSN: 1916-1107. Kadir, Abdul. 2005. Teknologi Konversi Energi Panas Laut:Prinsip, Perkembangan dan
Prospek. L.A.Vega,Ph.D. Marine Technology Society Journal, Ocean Thermal Energy Conversion
PrimerV. 6, No. 4 Winter 2002/2003 pp. 25-35
Mamahit, E.J.Calvin. Pengembangan Konversi Energi Panas Laut. Takahashi and Masutani.2001. Ocean Thermal Energy Conversion OTEC. University of
Hawaii at Manoa, Honolulu, HI, USA.
http://www.otecnews.org/http://www.ocees.com/mainpages/qanda.htmlhttp://www.ocees.com/mainpages/qanda.htmlhttp://www.ocees.com/mainpages/qanda.htmlhttp://www.otecnews.org/http://www.otecnews.org/