Conceptual design of a 5 MW OTEC power plant in the Oman Sea

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1 Journal of Marine Engineering & Technology ISSN: (Print) (Online) Journal homepage: Conceptual design of a 5 MW OTEC power plant in the Oman Sea Amir-Sina Hamedi & Sadegh Sadeghzadeh To cite this article: Amir-Sina Hamedi & Sadegh Sadeghzadeh (2017) Conceptual design of a 5 MW OTEC power plant in the Oman Sea, Journal of Marine Engineering & Technology, 16:2, , DOI: / To link to this article: Published online: 07 May Submit your article to this journal Article views: 205 View Crossmark data Full Terms & Conditions of access and use can be found at

2 JOURNAL OF MARINE ENGINEERING & TECHNOLOGY, 2017 VOL. 16, NO. 2, Conceptual design of a 5 MW OTEC power plant in the Oman Sea Amir-Sina Hamedi a and Sadegh Sadeghzadeh b a Department of Energy, Sharif University of Technology, Tehran, Iran; b School of New Technologies, Iran University of Science and Technology, Tehran, Iran ABSTRACT Developing ocean energy extraction, including ocean thermal energy conversion (OTEC), has been of interest to researchers for many decades. OTEC is a free fuel technology and could be used as a baseline power generation. These advantages plus the engineering challenge have resulted in researchers striving to design and construct prototype devices. Making use of worldwide experience, all sections of a conceptual design including site selection, technical specifications and cost estimation were carried out for an Iranian OTEC power plant. A 5 MW closed cycle floating plant with an annual average temperature difference of 22 C was chosen at a 33 km distance from Chabahar harbour. Deep seawater would be extracted from 1000 m depth and would result in 3.52 MW of net power. According to cost calculations, the levelised cost of electricity of the plant has been estimated to be approximately $/kwh, which is an acceptable level compared to other renewables. The conceptual OTEC design presented in this paper demonstrates a thermal potential in the Oman Sea which could assist with meeting the power demand for the southern coast of Iran. ARTICLE HISTORY Received 24 April 2016 Accepted 13 April Introduction Increased worldwide energy consumption, environmental concerns and the oil crisis of the 1970s have intensified interest in exploiting renewable energy. Oceans and seas provideinspirationforengineerstoutiliseenergyofseawater in various ways. These ways can be divided into two main areas: wave energy (mechanical) and temperature difference (thermal). However, today, researchers have in general focused more on wave energy than thermal energy conversion. Ocean thermal energy conversion (OTEC) is a system which uses the temperature difference between warm surface seawater and cold deep seawater to drive a workingfluidinarankincycletoproduceelectricity. The warm seawater evaporates a working fluid, typically ammonia, in a heat exchanger and the cold seawater, which is extracted from 500 to 1000 m depth, is used to condense the ammonia vapour after it has driven a turbine. Surface seawater varies with a range of C depending on season, while deep seawater often does not change significantly by season and remains fairly steady in the range of 5 9 C. An average temperature difference of 20 C is needed to drive the Rankin heat engine and produce an approximately constant base-load power (Griekspoor 1981). OTEC technology can utilise different power production cycle types. Closed cycle runs a heat engine by generating a pressure difference in a working fluid. Open cycle OTEC uses seawater as the working fluid by providing a relative vacuum in the heat exchanger generating lowpressure steam. Also a combination of closed and open cycles,namedkalina,usesbothwaterandammoniaas working fluids. Other variations for OTEC technology include location. Onshore units are land-based and offshore units are either free floating/grazing or moored to the sea bed. OTEC technology generates electricity continuously and could be used as a base-load power plant, which is a major advantage compared to other renewable energies including solar and wind. The resource of ocean thermal energy is worldwide, which means this technology could providebenefittomanynations.althoughtherearesome potential adverse effects including possible release of CO 2 absorbed in seawater and fish entrapment, depending on intake grill design, OTEC technology is considered to be environment-friendly (Ruud Kempener (IRENA), Frank Neumann (IMIEU) 2014). Sinceatestplantupto1MWcapacityhasbeen installed, the present main challenges of developing OTEC are deployment of the water duct system and CONTACT Sadegh Sadeghzadeh sadeghzadeh@iust.ac.ir 2017 Institute of Marine Engineering, Science & Technology

3 JOURNAL OF MARINE ENGINEERING & TECHNOLOGY 95 heat exchangers at a 5 MW or greater size and also the lack of long-term operating experience (Ruud Kempener (IRENA), Frank Neumann (IMIEU) 2014). The location of Iran near seas with OTEC potential encourages us to develop a conceptual design of an OTEC plant to provide energy for coastal regions. 2. OTEC technology progress 2.1. History The idea of OTEC dates back to the nineteenth century when a French physicist, Jacques d Arsonval, suggested a system which converts the temperature difference within seawater to generate electricity by means of a heat engine. This idea was discarded until 1925 when one of his students, Georges Claude, built the world s first OTEC plant in Cuba (Uehara et al. 1988). Due to energy crisis of the 1970s, interest in constructing large-scale OTEC prototypes was reignited. Companies and organisations in the US and Japan built test OTEC plants and urged other countries, including the UK and Sweden to become involved in OTEC projects. In Table 1 there is a list of significant OTEC plants which have been or are planned to be installed worldwide. As Table 1 demonstrates there is no record of OTEC utilisation, either prototype or in large scale in Iran, thus, this paper aims to explore the thermal potential of the seas around Iran and also to develop a conceptual design Design parameters ThecomponentsofanOTECopencycleareshownin Figure 1: condenser, evaporator, turbo-generator, pumps, pipingandpowercables.inanopencycle,warmwater from surface seawater flows through a flash evaporator drum. The developed vacuum causes seawater to evaporateattherelativelylowseawaterintaketemperature of C. The vapour flow drives a low-pressure turbine and generator and then condensed in a drum by pumped deep seawater. This drum also is vacuumed to facilitate condensing. The discharged water from the condenser could be used for cooling systems such as air conditioning or as fresh water, which introduces multiproduct OTEC plants, which can improve profitability. The major difference between closed and open cycle is the working fluid (a refrigerant, mostly ammonia, in closed cycle), which alters the plant equipment arrangement. In the closed cycle, ammonia is condensed and evaporated by deep cold seawater and surface warm seawater, respectively. In these two drums the pressure is high due to the boiling point of ammonia at the intake seawater temperature range. This pressure difference between evaporator and condenser makes ammonia vapour flow through the turbine and generate electricity. Efficiency is a key parameter which influences whether or not a technology is feasible. Due to Carnot and Rankin efficiency and other losses at the turbo-generator and pumps, the energy conversion efficiency associated with OTEC technology is low. Although a typical Carnot efficiency of an OTEC plant is about 6 8%, the real cycle efficiency is estimated at between 2% and 4% (Lavi 1980). Enormous quantities of cold and warm seawater are needed to run an OTEC plant, which also requires substantial heat exchangers and pipes. However, because the warm and cold seawater is effectively a free fuel and due to progress in heat exchanger and pipe material design and manufacture, large-scale OTEC plants are now starting to reach the stage of economic viability in comparison to other renewable energies, particularly in areas where electricity, fresh water and air conditioning costs are high. Table 1. Important worldwide installed or planned OTEC power plants (Ravindran 2000; Wikipedia contributors 2015a). Location Nominal or nameplate power output Description Hawaii 50 kw One of the oldest plant, 1979, closed cycle, Lockheed Missile and Space Co. Japan/Nauru 120 kw Installed in 1982 by Tokyo Electric Power Services Company Hawaii 1 MW A land-based plant, open cycle, operating between by LLC and NELHA Japan/Okinawa 50 kw A land-based plant using for power generation and research on other applications of OTEC, installed in 2013 by Xenesys, IHI and Yokogawa Hawaii 10 MW Working with the U.S. Navy and the Department of Energy, Lockheed Martin has invested $15 million over the past three years toward the technology need for and the design of a 10 MW prototype plant to validating the technologies necessary for small- to large-scale (100 MW or greater) commercial sized OTEC power plants India/Tuticorin south India 1 MW A floating closed cycle plant was attempted by the National Institute of Ocean Technology, India. Difficulties in connecting the 1 km cold water pipe due to lack of marine infrastructure led to closure of the project Southern China 10 MW The 10 MW prototype offshore plant will be the largest planned OTEC project until Like the Hawaii project, which was also to be a 10 MW facility, the China OTEC plant is designed to pave the way for higher capacity plants ranging from 10 to 100 MW Martinique/Bellefontaine 10 MW Floating platform, planned to operate from 2016, DCNS France

4 96 A.-S. HAMEDI AND S. SADEGHZADEH Figure 1. OTEC open cycle schematic. 3. Conceptual design 3.1. Site selection This section investigates an appropriate site for an OTEC plant installation making use of Iran s long 2700 km coastline (Wikipedia contributors 2015b). The major concern is water depth since the water depth in Caspian Sea and Persian Gulf (near the shore) is limited to 200 m. Henceitwaseasytoputasidethesetwooptionsand instead investigate the Oman Sea (Wikipedia contributors 2015c). Heading to the east in the Oman Sea, the depth increases up to 3400 m near Chabahar harbour (Wikipedia contributors 2015b). Therefore, this area was investigated further to assess the temperature profile and depthneartheharbourtofindanappropriatesite. Unfortunately, there is no sufficient data for depth and temperature profile for the Oman Sea in standard references. Therefore, it was necessary to use somewhat less comprehensive data. Figure 2(a,b) presents 10 years average of the Oman Sea water temperature and average variation temperature of the Arabian Sea (nearest sea to the Oman Sea) for both summer and winter, respectively. According to the average vertical temperature profile, the water temperature at 300 m is 17.5 C, so there is a need to go deeper to reach the required cold seawater. Unfortunately, deep seawater temperature data for this area are not found in standard references. Therefore, it was necessary to use the general sea temperature profilesasseeninfigure3. Figure 2. Seawater temperature difference of the Oman Sea (a) and the Arabian Sea in depth and various seasons (b) (Piontkovski and Chiffings 2014).

5 JOURNAL OF MARINE ENGINEERING & TECHNOLOGY 97 Figure 3. General deep seawater temperature profiles for different latitudes the Atlantic Ocean (Piontkovski et al. 2012). conceptual design to use these data to estimate the temperature at depths of 500, 750 and 1000 m in the Oman Sea at 9 C, 7 C and 5 C, respectively. Based on Figures 2 and 3 it was possible to prepare Table 2. As Table 2 demonstrates, the 22 C temperature difference probably exists at 1000 m depth. Therefore, the next stage was to inspect the nearest area to the Chabahar harbour to identify a 1000 m depth location for cold water extraction. To find this site Google earth maps was utilised. From Figure 4, three sites near Chabahar were identified which have 500, 750 and 1000 m water depth. Due to the illustrated reasons, site 3 was chosen as the cold water extraction site is 33 km far from the harbour and at 1000 m water depth a temperature of 5 C is expected to be available. Table 2. Annual temperature difference of Oman Sea at depth difference of 500, 750, 1000 m by seasons. 500 m 750 m 1000 m July June January February Average ( C) Figure 3 shows that both mid-latitudes and tropics temperature below 600 m water depth are approximately the same. Hence, it was judged acceptable for a 3.2. Technical specification The distance of deep cold seawater extraction point to shore would restrict the feasibility of an onshore plant, as capital costs are increased by the 33 km cold water pipe distance as well as associated reduction in thermodynamic efficiency. Hence, an offshore platform was chosen to minimise costs. If open cycle should be selected, the condenser discharged water could have other applications such as provision of fresh water or for use in cooling systems. Since there is no island near this site to deliverdischargedwater,plusconstructinganopencycle Figure 4. Three site features in the Oman Sea near the Chabahar harbour. Image 2015 CNES/Astrium; Data SIO, NOAA, U.S. Navy, NGA, GEBCO; Google; Image 2015 DigitalGlobe.

6 98 A.-S. HAMEDI AND S. SADEGHZADEH Table 3. Ammonia physical properties (Ammonia (data page) 2015 June 5). Parameter Value Formula NH 3 Molecular weight g/mole Boiling point (1 bar) 33.3 C Boiling point (5 bar) 10 C Boiling point (10 bar) 25 C Latent heat 1187 kj/kg Specific density demands more capital cost, selecting a closed cycle plant was preferable. Therefore, a 5 MW offshore closed cycle OTEC plant was selected. A refrigerant needs to be identified to act as the working fluid in a closed cycle system. Anhydrous ammonia is the most common and available refrigerant; thus, it is important to check ammonia s physical properties for the site-specific operating conditions. According to Table 3 ammonia sboilingpointat1bar is 33.3 C. Considering that the cold water intake temperature is 5 C, providing a 33.3 C temperature is not possible. Hence, it is necessary to change the condenser and evaporator operating pressures to adjust ammonia s boiling and condensing points to the two seawater intakes temperature. Table 3 shows ammonia s condensing and boiling points at 5 and 10 bar which are 10 C and 25 C, respectively, which match the cold and warm seawater temperatures. The closed cycle operating condition is illustrated in Figure 5. Carnot and cycle efficiency is estimated via the following equations: η carnot = T Hot T Cold = 22 T Hot 300 = 0.073, η cycle = W Q = 1 T Cold T Hot (1) 278 = = To calculate water intake flow rate Equation (2) is applied as follows: Q c = P ηc T c = Q h kg/s kj/s 6435 kg/s, (2) Average temperature difference between inlet and outlet cold and hot seawater is 5 C and 3 C, respectively, and cycle efficiency as mentioned previously is assumed to be 3.7%. Thus, the seawater flow rate in the condenser and evaporator becomes around 6430 and 10,720 kg/s, respectively. The selected heat exchanger material plays a key role with respect to estimating heat transfer area. Dissolved saltsandairmakeseawatercorrosive;thus,utilisinga corrosion-resistant material with high heat transfer coefficient has been studied in many marine journals. Titanium grade 1 has better characteristics than other metals Figure 5. Operating condition of the proposed closed cycle OTEC plant.

7 JOURNAL OF MARINE ENGINEERING & TECHNOLOGY 99 Table 4. Thermo-fluid parameters compared to other published designs. Parameter Value Unit Other notes Working fluid Ammonia Inlet/outlet water temperature difference 3 and 5 C 3.1 and 5.8 in Magesh (2010) and Vega (2002) Seawater flow rate 10,720 kg/s 13,900 kg/s for a 8 MW plant in Uehara et al. (1988) Heat exchanger material Titanium and steel alloy Titanium in Upshaw (2012) and Griekspoor (1981) LMTD 4 and 5.4 C 2.89 and 4.37 in Siahaya and Salam (2010) Overall heat transfer coefficient 4 kw/m 2 K 4inMagesh(2010) Condenser heat transfer area 8446 m 2 10,400 for a 5 MW plant in Uehara et al. (1988) Evaporator heat transfer area 6255 m 2 Ammonia flow rate 114 kg/s 137 in Uehara et al. (1988) and polymers (Griekspoor 1981) and the overall heat transfer coefficient is in order of 4 kw/m 2 K. However, some chemicals including chlorine should be added periodically to prevent microorganism build up in the heat exchangers. Another determinant variable is logarithmic mean temperature difference (LMTD). This parameter is an average between seawater inlet and outlet temperature and condensing or boiling points, which is calculated as Equation (3): LMTD C = (T con T c,in ) (T con T c,out ) Ln ( Tcon T c,in T con T c,out ) = 4 C, LMTD H = 5.4 C. (3) LMTD for the condenser and evaporator is 4 C and 5.4 C, respectively, and the heat transfer area is estimated by Equation (4) as follows: P A C = ηulmtd C 5000 = kw 8446 m 2, m 2 C 4 A E 6255 m 2. (4) According to Equation (3) the heat transfer area for the condenser and evaporator would become 8445 and 6255 m 2, respectively. The working fluid flow rate is another major parameter which is calculated by Equation (5): Q E = AULMTD E = m a LH a. (5) This can be calculated to be 114 kg/s. To validate and compare the overall values, the last column of Table 4 provides some variables which exist in other references. One of the most substantial factors in cost estimation relates to the heat exchangers. There are many different typesofheatexchangersbutforthepresentapplication, plate and frame heat exchangers are preferred. This is Figure 6. Plate and frame evaporator sizing. duetohighturbulenceandeasycleaningforplateheat exchangers,thusthebio-foulingfactorislowandasa result, an improved heat transfer coefficient is obtained. Moreover, in a constant duty application, a plate heat exchanger takes up less space than a shell and tube; therefore, in a restricted space floating plant, selecting a plate heat exchanger is desirable. Due to limitations in plate numbers in heat exchangers, the size needs to be optimised. Assuming four plate heat exchangers each for the condenser and evaporator, there would be about 603 and 447 plates for the condenser and evaporator, respectively (with each plate active area of 3.5 m 2 ) seederivationbelow: N C = A a n = 8446 = 603 plates, N E = A a n = 6255 (6) = 447 plates The dimensions of the heat exchangers are illustrated in Figure 6. Thelastpartofthetechnicaldesignrelatestopiping and pumps. There are many potential compositions and alloys for pipes including steel, aluminium, plastic, concrete and fibres composites. Due to seawater s corrosive nature and pipe scaling effect, the most resilient composition was selected to resist bio-fouling. Plastic or fibre-reinforced composites are suitable due to capability for in-site extrusion and flexibility, which can resist the sub-sea flows (Griekspoor 1981;Vega2002).

8 100 A.-S. HAMEDI AND S. SADEGHZADEH Table 5. Thermo-fluid pipe and pump parameters. Parameter Value Unit Comparison with other designs Evaporator plate dimensions (each) 1.75*2*5.58 m m 2 (5 MW onshore) (Uehara et al. 1988) Condenser plate dimensions (each) 1.75*2*7.53 m 4.6*1*6.1 (4 MW) (LUISA) Cold water pipe 2.8 (1000 m length) m 7.5 m for 10 MW plant in Griekspoor (1981) Hot (warm) water pipe 3.7 (20 m length) m 7 m for 25 MW plant in Uehara et al. (1988) Pipe composition Fibre-reinforced composites fibre-reinforced composites in Griekspoor (1981) Cold water pump flow rate 6.43 m 3 /s Hot (warm) water pump flow rate m 3 /s Cold water pump power 793 kw Hot (warm) water pump power 515 kw Working fluid pump power 172 kw Net power output 3520 kw 3660 for a 5 MW plant in Uehara et al. (1988) Mixed effluent pipe diameter 4 m Mixed effluent pipe depth 60 m There are two parts of head loss in seawater pipes, which needs to be made up by pumps. One is piping friction and the other is head loss in the heat exchangers. By estimating head loss, seawater intake pumps power can be estimated. It is possible to decrease pumping power by increasing pipe diameter. Typically, there is a limitation on inlet fluid velocity (normally around 1 m/s) to avoid heat exchanger seal damage and also to account for material resistance. Moreover, to mitigate possible environmental issues, warm and cold seawater would normally be mixed and discharged at a moderate water depth; thus, a 4 m diameter pipe was designed to discharge the mixed warm and cold seawater at a 60 m water depth. Pipes and pumps parameters are presented in Table 5: 3.3. Cost estimation To investigate OTEC technology investment feasibility, it is necessary to estimate the levelised cost of electricity (LCOE) and compare this with other possible power plant technologies. LCOE is divided into two main costs: capital cost (CAPEX) and operating cost (OPEX). To have a more precise cost evaluation it is desirable to use a dynamic model, which is defined in more details in the references. To avoid excessive length, in this paper all that is reported are the final calculations. Considering cost estimations for real OTEC projects all over the world, and considering lower construction costs in Iran the calculated capital cost for each component and the final CAPEX value are summarised in Table 6. Due to free fuel, the OPEX estimation is divided into two parts including labour cost and maintenance. Seventeen personnel support a floating 5 MW OTEC plant, with each receiving a salary of 12,000 $ per year. Maintenance costs have been estimated at 5% of the total capital cost per year. Thus, these two costs would become 204,000 and 1,612,000 $ per year, respectively. Table 6. CAPEX estimation (Cavrot 1993; Magesh, 2010; Ruud Kempener (IRENA), Frank Neumann (IMIEU), 2014). Parameter Cost per unit Cost ($) Heat exchanger 500 $/m 2 7,350,000 Turbo-generator 700 $/kw 3,500,000 Pump 1000 $/kw 1,480,000 Seawater pipe 500 $/m 540,000 Platform 1100 $/kw 5,500,000 Cabling (33 km) 700 $/kw 3,500,000 Rankin cycle 1000 $/kw 5,000,000 Other costs 20% of total 5,374,000 Total 32,244,000 Considering a discount rate (i = 8%) and a project lifetime (n = 25 y) the cost recovery factor (CRF) can be calculated. The other affecting parameter is the capacity factor (CF), which addresses the period of year the plant will be fully operational producing net power. According to Lavi (1980), CF could be assumed to be 0.9. Therefore, the LCOE is calculated as follows: [ ] $ LCOE kwh [ ] $yr = CAPEX[$] CRF [yr 1 ] + OPEX ] W electricity [kw] 8760 CF [ hr yr 32, 244, , 816, 000 = = $/kwh. (7) There is a summary of economic parameters from otherdesignscomparedtotheonespresentintable7. Table 8 includes LCOE of common power plant technologies which can be compared to LCOE for the OTEC plant described in this paper. According to Table 8 OTEC technology has lower LCOE in comparison with solar PV and offshore wind andhenceinduecourseislikelytobeconsideredseriously as an alternative renewable energy technology.

9 JOURNAL OF MARINE ENGINEERING & TECHNOLOGY 101 Table 7. Economic parameters estimation. Parameter Value Unit Comparison with other designs Gross power 5 MW Netoutputpower 3.52 MW Capital cost 32,244,000 $ 42 $M for a 5 MW plant (Vega), $M for a 25 MW plant (Uehara et al. 1988) Operating cost 1,816,200 $/yr 2 $M for a 5 MW plant (Siahaya and Salam 2010), 6$M for a28mw(magesh2010), 1.6$Mfora5MWplant (Uehara et al. 1988) CRF yr 1 CF 0.90 In range of (Lavi 1980) LCOE $/kwh $/kwh in (Lavi 1980), $/kwh for an onshore 5 MW plant (Uehara et al. 1988) Table 8. LCOE comparison between various different power plant technologies (Ruud Kempener (IRENA), Frank Neumann (IMIEU), 2014). Technology Min. LCOE value ($/kwh) Conv. coal 0.09 N.G. conv. combined cycle Adv. nuclear Wind Solar PV Geothermal Biomass Offshore wind Solar thermal Conclusion The conceptual design demonstrates that Iran s potential for an OTEC power plant deployment in the Oman Sea shouldbepursuedseriously.someimportantpointshave been determined which are discussed below: (1) Investigating the temperature difference between the surface and deep seawater shows an adequate temperature difference in different seasons with an average of 22 C. This shows the potential of the Oman Sea for OTEC plants. (2) Due to the long distance of the selected site (33 km) to harbour, an offshore floating plant is proposed. This remoteness dictated a closed cycle OTEC plant, since the delivery of discharge desalinated water is not economic. (3) Technical progress in floating production technology and OTEC components make this technology feasible.somebottlenecksinthepastincludingheat exchangers and cold water pipe deployment are now believed to be surmountable. (4) Estimated LCOE ( 0.12 $/kwh) using CAPEX and OTEX appears acceptable compared to alternative renewable options, including solar PV and offshore wind technology. Based on the conceptual design presented in this paper, constructing a 5 MWe floating closed cycle OTEC power plant, located at a site relatively close to Chabahar harbour is proposed. Disclosure statement No potential conflict of interest was reported by the authors. ORCID Amir-Sina Hamedi References Ammonia (data page) Jun 5. InWikipedia, thefree encyclopedia [Internet]. [cited 14:48, 2015, Aug 3]. Available from: = Ammo nia_(data_page)&oldid = Cavrot DE Economics of ocean thermal energy conversion (OTEC). Ren Energy. 3: Griekspoor W Oceanthermalenergyconversion. Res Conser. 7: Lavi A Ocean thermal energy conversion: a general introduction. Energy. 5: Luisa V Ocean thermal energy conversion Hawaii Natural Energy Institute, School of Ocean and Earth Science and Technology. Honolulu (HI): University of Hawaii at Manoa. Magesh R OTEC technology a world of clean energy and water. London, UK: World Congress on Engineering (WCE). Piontkovski SA, Chiffings T Long-term changes of temperature in the Sea of Oman and the western Arabian Sea. Int J Oceans Oceanography. 8: SergeyA.Piontkovski,HamedM.H.Al-Gheilani,BarryP. Jupp, Adnan R. Al-Azri, Khalid A. Al-Hashmi InterannualchangesintheSeaofOmanecosystem.OpenMarine Biol J. 6: Ravindran M The Indian 1 MW floating OTEC plant an overview. IOA Newslett 11: 8 9. Ruud Kempener (IRENA), Frank Neumann (IMIEU) Ocean thermal energy conversion technology brief, Irena (International Renewable Energy Agency) Ocean Energy Technology Brief 1 June Siahaya Y, Salam L Oceanthermalenergyconversion (OTEC) power plant and its by products yield for small islands in Indonesia sea water. ICCHT-5th International Conference on Cooling and Heating Technologies, Bandung, Indonesia. Uehara H, Dilao CO, Nakaoka T Conceptualdesignof ocean thermal energy conversion (OTEC) power plants in the Philippines. Solar Energy. 41: Upshaw CR Thermodynamic and economic feasibility analysis of a 20 MW ocean thermal energy conversion (OTEC) power plant [MSc thesis] [Internet]. University of Texas, May [cited 2015 Mar 23]. Available from: repositories.lib.utexas.edu/handle/2152/etd-ut Vega LA Ocean thermal energy conversion primer. Marine Technol Soc J. 36:

10 102 A.-S. HAMEDI AND S. SADEGHZADEH Vega LA Economics of ocean thermal energy conversion (OTEC):anupdate.OffshoreTechnologyConferenceheldin Houston, Texas, USA, 3-6 May doi: /21016-ms Wikipedia contributors. 2015a.Oceanthermalenergyconversion. Wikipedia,TheFreeEncyclopedia. 31 Jul Web. 19 Aug Available from: index.php?title = Ocean_thermal_energy_conversion&old id = Wikipedia contributors. 2015b.GulfofOman.Wikipedia, The Free Encyclopedia. 11 Jul Web. 3 Aug Available from: = Gulf_of_ Oman&oldid = Wikipedia contributors. 2015c. Persian Gulf. Wikipedia, The Free Encyclopedia. 9 Aug Web. 19 Aug Available from: = Persian_ Gulf&oldid =