Seawater difference of temperature generation
公開日: 2013/07/11
佐賀大学教授 池上康之さんの夢の扉です。
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http://www.ioes.saga-u.ac.jp/en/about_oetc.html
Ocean Energy
There is plenty of energy stored in ocean seawater in various forms. Successful recovery of such energetic substances will provide us with environmentally friendly energy, which will replace fossil fuel. Utilization in concrete forms of such energy is highly sought henceforth.
Fig. 1 Worldwide distribution of difference temperatures of seawaters between surface and depth at 1,000m
Fig. 2 Vertical temperature distribution of seawater
The power generation system using a small temperature deference into the seawater is called Ocean Thermal Energy Conversion (OTEC). Fig. 3 shows the principle of OTEC. The system consists of evaporator, condenser, turbine, power generator and pump. These components are connected in pipe that is enclosed the working fluid like an ammonia. The liquid working fluid is sent to the evaporator with a pump. Then the working fluid was warmed by surface hot seawater and becomes vapor. vapor turns a turbine driving an electrical generator and generating electricity. The vapor discharged from the turbine enters the condenser, and is condensed by cold seawater pumped up from deep sea, therefore, return to the liquid.
It can generate electricity by performing this repetition, without using a fossil fuel and uranium.
Fig. 3 A sketch of principle of OTEC
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http://www.ioes.saga-u.ac.jp/en/about_oetc.html
Ocean Energy
There is plenty of energy stored in ocean seawater in various forms. Successful recovery of such energetic substances will provide us with environmentally friendly energy, which will replace fossil fuel. Utilization in concrete forms of such energy is highly sought henceforth.
Utilization examples of ocean energy
| Ocean energy conversion | Power generation utilizing temperature difference between surface and deep sea water. |
| Ocean wave power conversion | Power generation utilizing energy stored in waves of surface seawater. |
| Ocean tide power generation | Power generation utilizing energy the difference between the rise and fall of the tide. This method is a kind of hydro power generation. |
| Ocean salinity gradient power generation | Salinity difference in seawater contributes to generate power. |
| Recovery of rare metals from seawater | Recovery of rare metals from seawater Lithium, uranium, and other substances existing in seawater in molten condition shall be recovered. |
| Deep Sea Water | Utilizing of deep seawater running down some 1,000m deep for processing for food, cosmetic, mariculture and other purposes. |
About Ocean energy
Quantity of Ocean Energy
According to measured temperature of seawater at surface and deep sea, there are large temperature difference between surface and deep seawater. Fig. 1 shows temperature difference distribution between sea water at ocean's surface and sea water at the depth of the 1000m in the world. Temperature of near equator is very high, 24 degrees. Amount of ocean energy is about 1000×1011kWh/year, which is estimated inside the Japanese economic water, 360km（200 nautical mile) of coast.
Conversion of the energy into oil is equivalent to about 8,600 million ton. Then, it was found that Japanese economic water has such large energy.
Conversion of the energy into oil is equivalent to about 8,600 million ton. Then, it was found that Japanese economic water has such large energy.
Fig. 1 Worldwide distribution of difference temperatures of seawaters between surface and depth at 1,000m
Temperature Distributions of Seawater
Fig. 2 shows the vertical temperature distribution of seawater at tropical and subtropical zone. It was found the temperature of sea water continues falling until a depth of about 700m.Fig. 2 Vertical temperature distribution of seawater
Ocean Thermal Energy Conversion (OTEC)
The power generation system using a small temperature deference into the seawater is called Ocean Thermal Energy Conversion (OTEC). Fig. 3 shows the principle of OTEC. The system consists of evaporator, condenser, turbine, power generator and pump. These components are connected in pipe that is enclosed the working fluid like an ammonia. The liquid working fluid is sent to the evaporator with a pump. Then the working fluid was warmed by surface hot seawater and becomes vapor. vapor turns a turbine driving an electrical generator and generating electricity. The vapor discharged from the turbine enters the condenser, and is condensed by cold seawater pumped up from deep sea, therefore, return to the liquid.
It can generate electricity by performing this repetition, without using a fossil fuel and uranium.
Fig. 3 A sketch of principle of OTEC
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Ocean thermal energy conversion
From Wikipedia, the free encyclopedia
Ocean thermal energy conversion (OTEC) uses the temperature difference between cooler deep and warmer shallow or surface ocean waters to run a heat engine and produce useful work, usually in the form of electricity. OTEC is a base load technology that allows for production of electricity on a constant basis. However, the temperature differential is small and this impacts the economic feasibility of ocean thermal energy for electricity generation.
The most commonly used heat cycle for OTEC is the Rankine cycle using a low-pressure turbine. Systems may be either closed-cycle or open-cycle. Closed-cycle engines use working fluids that are typically thought of as refrigerants such as ammonia or R-134a. These fluids have low boiling points, and are therefore suitable for powering the system’s generator to generate electricity. Open-cycle engines use vapour from the seawater itself as the working fluid.
OTEC can also supply quantities of cold water as a by-product. This can be used for air conditioning and refrigeration and the nutrient-rich deep ocean water can feed biological technologies. Another by-product is fresh water distilled from the sea.[1]
Demonstration plants were first constructed in the 1880s and continue to be built. Currently the world's only operating OTEC plant is in Japan, overseen by Saga University.
The most commonly used heat cycle for OTEC is the Rankine cycle using a low-pressure turbine. Systems may be either closed-cycle or open-cycle. Closed-cycle engines use working fluids that are typically thought of as refrigerants such as ammonia or R-134a. These fluids have low boiling points, and are therefore suitable for powering the system’s generator to generate electricity. Open-cycle engines use vapour from the seawater itself as the working fluid.
OTEC can also supply quantities of cold water as a by-product. This can be used for air conditioning and refrigeration and the nutrient-rich deep ocean water can feed biological technologies. Another by-product is fresh water distilled from the sea.[1]
Demonstration plants were first constructed in the 1880s and continue to be built. Currently the world's only operating OTEC plant is in Japan, overseen by Saga University.
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Kume Island
http://en.wikipedia.org/wiki/Kume_Island
Kume Island[1] (久米島 Kumejima, Okinawan: クミジマ Kumijima) is an island, part of the Okinawa Islands and administratively part of the town of Kumejima, Okinawa Prefecture, Japan. It has an area of 59.11 metres (193.9 ft).[2] The island had a population of 8,713 (2010).
Kume Island is a volcanic island. Its principal economic activities are the production of sugarcane and tourism.[3]
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