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Ocean thermal energy conversion (OTEC) uses the temperature difference between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity. OTEC is a base load electricity generation system. However, since the temperature differential is small, the thermal efficiency is low, making its economic feasibility a challenge. Among ocean energy sources, OTEC is one of the continuously available renewable energy resources that could contribute to base-load power supply.〔Lewis, Anthony, et al. IPCC: Special Report on Renewable Energy Sources and Climate Change Mitigation, 2011〕 The resource potential for OTEC is considered to be much larger than for other ocean energy forms (Energy Council, 2000 ). Up to 88,000 TWh/yr of power could be generated from OTEC without affecting the ocean’s thermal structure (and Fujita, 2002 ). Systems may be either closed-cycle or open-cycle. Closed-cycle OTEC uses 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. The most commonly used heat cycle for OTEC to date is the Rankine cycle, using a low-pressure turbine. 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.〔 OTEC theory was first developed in the 1880s and the first bench size demonstration model was constructed in 1926. Currently the world's only operating OTEC plant is in Japan, overseen by Saga University. == History == Attempts to develop and refine OTEC technology started in the 1880s. In 1881, Jacques Arsene d'Arsonval, a French physicist, proposed tapping the thermal energy of the ocean. D'Arsonval's student, Georges Claude, built the first OTEC plant, in Matanzas, Cuba in 1930.〔 〕〔("Power from the Sea" ''Popular Mechanics'', December 1930, pp 881-882 ) detail article and photos of Cuban power plant〕 The system generated 22 kW of electricity with a low-pressure turbine. The plant was later destroyed in a storm.〔Avery, William H. and Chih Wu. Renewable Energy From the Ocean: A Guide to OTEC. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ocean thermal energy conversion」の詳細全文を読む スポンサード リンク
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