Energy and the environmenta coastal perspective opencycle. Pdf a closed cycle ocean thermal energy conversion basically involves a working fluid which has a boiling. Placing warm seawater in a lowpressure container causes it to boil. Figure 3 schematic diagram of an opencycle otec system.
Preliminary results robert gresham, levi thornton, brendon rankou. Open cycle otec thermalhydraulic systems analysis and. Closed cycle ocean thermal energy conversion systems use a working fluid with a low boiling point, ammonia for example, and use it to power a turbine to generate electricity. One source of renewable energy is ocean thermal energy conversion otec system. Open cycle otec systems can produce desalinated water which is very important in thirdworld countriesvi. A hybrid ocean thermal energy conversion otec system, including an energy generation sub system for receiving warm sea water, evaporating a working fluid at a natural depth of the received warm sea water to produce a working vapor, and generating energy from the working vapor and a pumping sub system for pushing cold sea water up to a natural depth of the. The present status and features of otec and recent. The resultant steam is expanded through a lowpressure steam. Hybrid design otec the hybrid cycle is one that has yet to be tested but uses principles from both the closed and open cycle otec systems to obtain maximum efficiency. We have developed an analytic thermohydrauli c systems model of the power cycle and seawater supply systems for an open cycle ocean thermal energy conversion otec plant that allows us ready examination of the effects of system and component operating points on plant size and parasitic power requirements. Electricity generation by the ocean thermal energy. First is the open cycle system, which uses seawater as the working fluid. Although otec relies on an enduring source, it is undoubted there are economic challenges. These fluids have low boiling points, and are therefore suitable for powering the system s generator to generate electricity.
Pdf the ocean thermal energy conversion strategies and. The steam expands through a lowpressure turbine that is coupled to a. The warm seawater is flashevaporated in a vacuum chamber to produce steam at an absolute pressure of about 2. Schemes and cycles for ocean temperature differences. In open cycle otec, the sea water is itself used to generate heat without any. Opencycle otec system energy technology britannica. In this kind of system, warm surface seawater is partially vaporized as it is injected into a near vacuum. The vapor expands through the turbine and is condensed with cold sea water.
Based on the power cycle the otec system can be classified in to two viz. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. The oceans cover a little more than 70 percent of the earths surface. Warm seawater is taken in from the surface of the oceans and cold water from the deep at 5 o.
Claudes cycle is also referred to as opencycle otec ocotec because the working fluid flows once through the system. In this system, the warm surface water is flashevaporated in a chamber maintained under high vacuum and the. The hybrid cycle uses both seawater and another working fluid, usually designed using ammonia. In an open cycle otec facility seawater is used as a working fluid. The significant expansion of development of opencycle otec systems began in 1984 with the development of a verticalspout evaporator. The former cycles use volatile working fluids refrigerants such as ammonia or r4a, whereas open cycle engines use vapor produced from the seawater. Numerical analysis of an ocean thermal energy conversion system. Otec facilities take advantage of the rankine cycle, a process which converts thermal energy into kinetic energy via turbines. Ocean thermal energy conversion engineering university of. The combined evaporatorcondenser further includes a plurality of evaporator spouts and a mist eliminator, wherein the pressure is maintained across the plurality of evaporator spouts. Opencycle ocean thermal energy conversion fsec energy. Anl was also responsible for environmental assessments. Otc 20957 first generation 50 mw otec plantship for the.
These three systems all employ the thermodynamics of a working heat exchanger and use the temperature differences naturally occurring in the ocean as the driving force. This system is more complex that either of the other cycles but it marries the compact closed cycle system with the ability to produce drinking water. The design oriented analysis of an otec system must consider both survivability design loads and operationalfatigue loads. Closedcycle otec power systems, which operate at elevated pressures, require smaller turbines than opencycle systems. A small 1 mw otec is capable of producing some 4,500 cubic meters of fresh water per day, enough to supply a population of 20,000 with fresh waterv. The steam that comes from the lowpressure boiling system is enough to power a turbine thus creating work 1. Open cycle otec warmer surface water is introduced through a valve in a low pressure compartment and flash evaporated. A system model of open rankine cycle ocean thermal energy conversion ocqtec was used to examine the effects of component performance and design on plant cost.
A system model of open rankine cycle ocean thermal energy conversion ocqtec was used to examine the effects of component performance and design on. Warm sea water is flash evaporated in a partial vacuum in the evaporator. The plant failed to achieve net power production because of a poor site selection e. In opencycle otec, warm sea water is used directly as the working fluid. In the open cycle warm seawater is located in a lowpressure tank and caused to then boil 1. Otec systemsotec systems there are three types of electricity conversionthere are three types of electricity conversion systems. The closed or anderson, otec cycle power plantthe closed or anderson, otec cycle power plant ii. The turbines can then be used to drive generators, producing electricity. Closedcycle otec uses working fluids that are typically thought of as refrigerants such as ammonia or r4a. This makes them the worlds largest solar energy collector and energy storage system. The otec system has three scenarios that can be harnessed in terms of ocean water temperature differentials which are a closed cycle, an open cycle, and a hybrid cycle. There are some decisive differences, however, between ordinary power generation systems and otec. In the ccotec system, warm surface seawater and cold seawater are used to vaporize and condense a working fluid, such as anhydrous ammonia, which drives a turbine. In an open cycle otec system, warm seawater is the working fluid.
Ocean thermal energy conversion systems slideshare. Vega, national marine renewable energy center at the university of hawaii. Us55494a ocean thermal energy conversion otec system. Principle and preliminary calculation of ocean thermal. The heart of it is a large turbine driven by steam, which is cooled by water pumped up from the deep ocean. Calculation of power pumps on otec power plant ocean. In a hybrid otec system, warm seawater enters a vacuum chamber where it is flashevaporated into steam, similar to the open cycle process. These include an open cycle 3, a hybrid cycle that. Conduct research in the areas of innovative turbine concepts for the large machines required for opencycle systems. Opencycle ocean thermal energy conversion otec research. Open cycle here 1,2,3,4,5,6,7,71,8 are the direction of flow in open cycle process. The open cycle system uses the warm seawater as the working fluid. In an opencycle system, steam generated from the warm seawater is the. The system analyzed here will operate in a closed cycle.
Basic heat exchanger performance evaluation method on otec. With this in mind, the first verification test was performed by making. First generation 50 mw otec plantship for the production of electricity and desalinated water luis a. Otec ocean thermal energy conversion principle your. There are also open cycle otec platforms, which can be beneficial as well. The steam vapourises the ammonia working fluid of a closed cycle loop on the other side of an ammonia vapourizer. Us5582691a ocean thermal energy conversion otec system. The closed rankine cycle otec is essentially the same cycle as that employed for ordinary thermal power plants as well as nuclear power generation. The otec ocean thermal energy conversion power plant is one candidate. The warm seawater vaporizes the fluid in the heat exchanger which then turns the turbines of the generator. Study of ocean thermal energy conversion system request pdf. Ocean thermal energy conversion technology britannica. The most commonly used heat cycle for otec is the rankine employing a lowpressure turbine and systems can be either closed cycle or open cycle. Otec transforms the heat stored in the surface water of tropical oceans, into.
Content of the seminar and pdf report for ocean thermal energy. Open and closed cycle ocean thermal energy conversion. A hybrid cycle combines the features of both the closed cycle and open cycle systems. In this system, the warm water layer of sea acts as a reservoir of heat source and cool water at the depth act as a reservoir of heat sink. He demonstrated this cycle in cuba claude, 1930 with a small landbased plant making use of a direct contact condenser dcc.
Numerical analysis of an ocean thermal energy conversion. Several techniques have been proposed to use this ocean thermal resource. A 210 kw gross open cycle shore based otec plant facility off the island of hawaii was designed built and run successfully by. There are two basic types of ocean thermal energy conversion otec systems which are as under. Study of ocean thermal energy conversion system article in mitigation and adaptation strategies for global change 82. Although somewhat outdated, otec 1the claude open cycle is referred to in this paper as ocotec, for convenience. This page contains ocean thermal energy seminar and ppt with pdf report. They convert the thermal energy in the ocean, which is reserved as the vertical temperature gradient in. Ocean thermal energy conversion otec types renewable.
The otec system also generates fresh water as a primary product and. Identify and evaluate advanced concepts for ocean thermal energy extraction. Created by the solar energy research institute, known today as the national renewable energy laboratory, the evaporator transforms warm ocean water into lowpressure steam. Electricity generation by the ocean thermal energy tethys. Ocean thermal energy conversion otec and the pacific islands page 9 open cycle otec system the open cycle system is generally similar to the closed cycle system and uses the same basic components. In closedcycle otec, warm seawater heats a working fluid with a low boiling point, such. One is the difference of thermal head, in other words, temperature difference between evaporation. Otec systems use the oceans natural thermal gradient. The warm seawater vaporizes the fluid in the heat exchanger which then turns the turbines of the. In the ccotec system, warm surface seawater and cold seawater are used to vaporize and condense a.
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