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Ocean Energy for Sustainable Townsville
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Townsville is perfectly positioned to become the leading international centre for the research, development and commercialisation of the ocean based renewable energy technology, OTEC. OTEC (Ocean Thermal Energy Conversion) is an technology that has long been considered a potential source of low-cost, carbon-neutral, base-load electricity as well as bulk desalinated water. Whle OTEC technology has been under development for over sixty years, the commercialisation of the technology has not yet been achieved. As the global price of energy increases in step with concern for reducing greenhouse emissions, a valuable opportunity presents itself for Townsville to take the lead in forming an international consortium to complete the excellent work commenced by OTEC researchers and developers around the world. The information below tells the story of OTEC and provides valuable links to OTEC resources on the intenet. |
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Townsville is considered a potential base for OTEC technology because:
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A vision for Townsville's Energy Future might include an ocean energy farm of 100 OTEC plants located 100 km offshore each producing 100 MW of base load power with a subsea cable feeding into the mains grid near Townsville. We call this vision one hundred by three. Additional uses of OTEC Infrastructure
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Potential Ecological Consequences The ecological impacts of OTEC plants would need to be thoroughly considered given the proximity of the Great Barier Reef Marine Park. Here are some preliminary considrations. The flow of water from a 100-megawatt OTEC plant, would equal the of a large river. Since the salinity of the ocean is nearly uniform, these large discharges will not significantly affect the salinity of the receiving waters. The temperatures of the seawater discharges will be some 3°C (6°F) above or below their initial temperatures. If the warm and cold discharges are mixed, they will have an temperature near 18°C (64°F). The water will need to be discharged at a depth below the bottom of the surface layer in order to avoid contaminating the surface water intake. At that depth, somewhere below 100 m, the discharge will be denser than the water at that depth and will disperse gradually downward, having little impact on the surface layer where most life exists. Information source: Ocean Atlas |
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5 MW preproduction plant The literature suggests that the next step is to build a demonstration plant of 5 MWe to establish life cycles of major components. Much of the design work has already been completed. See details: by Vega and Nihous, Pacific International entre for High Technology Research. Design of a 5 MWe OTEC Pre-commercial Plant |
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It will then be possible to construct 100 MWe floating plants. Design work by Sea Solar has begun on the 100 MW plant ship. Shown below is the Sea Solar Power 100 MW hybrid cycle OTEC . See brochure: 100 MW OTEC. |
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Sea Solar OTEC Inputs: |
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Potential Locations for OTEC Plants OTEC plants are ideally suited to areas with a large temperature difference between the surface and deep waters. This map shows the global distribution of there areas. Ideal locations for OTEC plants rely o not just the water temperatures, but access to the mains power grid and demand for electricity. |
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Koffi Annan, Secretary General of the United Nations, watches a presentation on the Japanese Uehara Cycle OTEC plant by Xenesys at the United Nations conference for Small Island Developing States, Mauritius, January 10-14, 2005. OTEC is proposed as a suitable technology to assist in providing water and power for small island states. However, because of the high development costs, the next stages of development would need to be undertaken by industrialised countries. |
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History of OTEC - a proven technology 1881 - J. D’Arsonval first proposed the
concept of driving turbines with ammonia using temperature difference of the oceans. see .pdf report on history of OTEC |
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OTEC Internet Resources |
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Sea Solar Power is an innovative company that has designed an economically efficient system to harness the solar energy from the tropical oceans to generate electricity, produce desalinated water, and to grow a variety of food for most of the world's population.
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National Institute of Ocean Technology A Rankine cycle with a working fluid such as ammonia is a first choice for extraction energy from the temperature difference. The essential components of the cycle are an evaporator, turbine-Generator, Condenser and a Pump for circulating the working fluid.
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World Energy Council Survey of Energy Resources Ocean Thermal Energy Conversion (OTEC) is a means of converting into useful energy the temperature difference between surface water of the oceans in tropical and sub-tropical areas, and water at a depth of approximately 1 000 metres which comes from the polar regions. |
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National Renewable Energy Laboratory The oceans cover a little more than 70 percent of the Earth's surface. This makes them the world's largest solar energy collector and energy storage system. On an average day, 60 million square kilometers (23 million square miles) of tropical seas absorb an amount of solar radiation equal in heat content to about 250 billion barrels of oil. |
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Ocean thermal energy conversion (OTEC) is perhaps the most exciting world energy resource for the future-the near future. It promises vast amounts of energy (even ten times the current worldwide human utilization) that is cheap (competitive with $25-per-barrel crude oil), naturally self-renewing, and ecologically friendly. As a beneficial side effect, OTEC can turn vast stretches of starved "ocean deserts" into lush "ocean oases" teeming with sea life. |
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Energy Efficiency and Renewable Energy Ocean Thermal Energy Conversion Systems. A great amount of thermal energy (heat) is stored in the world's oceans. Each day, the oceans absorb enough heat from the sun to equal the thermal energy contained in 250 billion barrels of oil. OTEC systems convert this thermal energy into electricity - often while producing desalinated water. |
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United Nations Environment Program Ocean energy draws on the energy of ocean waves, tides, or on the thermal energy (heat) stored in the ocean. Oceans cover more than 70% of Earth's surface, making them the world's largest solar collectors. The sun warms the surface water a lot more than the deep ocean water, and this temperature difference stores thermal energy. |
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Wikipedia on Ocean Thermal Energy Conversion Ocean thermal energy conversion , or OTEC , is a way to generate electricity using the temperature difference of seawater at different depths. Nearly all energy utilised by humans originates from some form of cyclic heat engine . A heat engine is placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work. |
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Ocean Thermal Energy Conversion Ocean thermal energy conversion , or OTEC , is a way to generate electricity using the temperature difference of seawater at different depths. Nearly all energy utilised by humans originates from a cyclic heat engine . A heat engine is placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work. |
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The heat exchangers (evaporator and condenser) are a large and crucial component of the closed-cycle power plant, both in terms of actual size and capital cost. Much of the work has been performed on alternative materials for OTEC heat exchangers, leading to the recent conclusion that inexpensive aluminum alloys may work as well as much more expensive titanium for this purpose. |
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Image source: Stanford
