Otec

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OCEAN THERMAL ENERGY CONVERSION

Abstract

Ocean Thermal Energy Conversion (OTEC), to me, is the developing worlds answer to OPEC (Organization of Petroleum Exporting Countries). We will no longer have to depend on oil supplies from other countries. OTEC is an efficient, clean process, which utilizes the difference in temperatures between the oceans surface and its depths to produce energy. The ocean thermal energy conversion process works something like a refrigerator in reverse. The warm surface waters vaporize a refrigerant and the vapour is then used to drive a turbine. The refrigerant vapour is then condensed back into a liquid after being cooled by cold water brought up from the ocean depths. This technology is best applied in the tropics like India, because the sun heats the ocean surface to comparably high temperatures, creating the highest temperature differentials between surface and depths, which translates into the largest potentials of energy production. This paper describes the status of the various ocean thermal energy technologies, with emphasis placed on those with a near-term potential and applicability in large numbers.

1. Introduction

Ocean Thermal Energy Conversion (OTEC) technology is based on the principle that energy can be extracted from two reservoirs at different temperatures. A temperature difference as low as 20°C can be exploited effectively to produce usable energy. Temperature differences of this magnitude prevail between ocean waters at the surface and at depths up to 1000 meters in many areas of the world, particularly in tropical and subtropical latitudes between 24 degrees north and south of equator. This thermal gradient—the fact that the ocean's layers of water have different temperatures—is effectively used to drive a power-producing cycle. The oceans are thus a vast renewable resource, with the potential to help us produce billions of watts of electric power. This potential is estimated to be about 1013 Watt of baseload power generation. The cold, deep seawater used in the OTEC process is also rich in nutrients, and can be used to culture both flora & fauna near the shore or on land.

2.HISTORY
“Those hot ocean waters have a more useful purpose than just generating hurricanes. A reverse refrigeration process generates electricity from, the difference in temperature between surface and deep water.” -By Sterling D. Allan

OTEC technology is not new. In 1881, Jacques Arsene d'Arsonval, a French physicist, proposed tapping the thermal energy of the ocean. But it was d'Arsonval's student, Georges Claude, who in 1930 actually built the first OTEC plant in Cuba. The system produced 22 kW of electricity with a low-pressure turbine. In 1935, Claude constructed another plant aboard a 10,000-ton cargo vessel moored off the coast of Brazil. Weather and waves destroyed both plants before they became net power generators. The United States involved in OTEC research in 1974 with the establishment of the Natural Energy Laboratory of Hawaii Authority. The Laboratory has become one of the world's leading test facilities for OTEC technology. Today, with a Power Purchasing Agreement between the government of Tamil Nadu, India, and Sea Solar Power SSP), Anderson (President, SSP) is preparing to construct a test facility near Tamil Nadu coast, for the power cycle.

Types of OTEC Plants:
1. Land or near the shore.
2. Platforms attached to the shelf.
3. Moorings or free-floating facilities in deep ocean water

2. WORKING OF OTEC [pic]

Figure 1: Schematic representation of OTEC

A Refrigerator in reverse: OTEC generates electricity by using the temperature difference of 20°C (36°F) or more that exists between warm tropical waters at the sun-warmed surface, and colder waters drawn from depths of about 1000 m. To convert this thermal gradient...
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