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How do we Harvest Energy from
Water?
Last Updated on:
12/01/2010 06:01 AM |
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Ocean energy draws on the energy
of ocean through two basic ways. One
way is thermal energy. Thermal
energy is provided by the sun. We harness the energy
that is stored in the surface layers of the ocean. The
second way is mechanical energy which come from
tides and waves. |
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Hydropower Energy |
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The term geothermal comes from
the Greek geo meaning earth and therine meaning heat thus geothermal energy is
energy derived from the natural heat of the earth. The earth’s temperature varies
widely, and geothermal energy is usable for a wide range of temperatures from room
temperature to well over 300° F. For commercial use, a geothermal reservoir
capable of providing hydrothermal (hot water and steam) resources is necessary.
Geothermal reservoirs are generally classified as being either low temperature
(<150° C) or high temperature (>150° C). Generally speaking, the high temperature
reservoirs are the ones suitable for, and sought out for commercial production of
electricity. Geothermal reservoirs are found in “geothermal systems” which are
regionally localized geologic settings where the earth’s naturally occurring heat
flow is near enough to the earth’s surface to bring steam or hot water to the
surface. Examples of geothermal systems include the Geysers Region in Northern
California, the Imperial Valley in Southern California, and the Yellowstone Region
in Idaho, Montana, and Wyoming.
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Hydropower Energy links
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Ocean Thermal Energy Conversion (OTEC) |
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The water at the surface of the
ocean is warmer than the water at deeper depths. This temperature difference can
be used by Ocean Thermal Energy Conversion (OTEC) systems to generate electricity.
Warm water from the surface and cold water pumped from deeper depths can be
utilized by three types of OTEC systems. Open-cycle OTEC uses the seawater itself
as the working fluid by boiling it at low pressures. This produces low-pressure
steam that passes through a turbine generator to produce electricity. The cold
water is used to condense the vapor back to a liquid. Closed-cycle OTEC uses warm
surface water to vaporize a low-boiling point working fluid, such as ammonia. The
expanding vapor of the working fluid drives a turbine generator to produce
electricity. The cold water is used to condense the vapor back to a liquid, which
is recycled by the system. Hybrid systems employ both closed-cycle and open-cycle
systems. OTEC systems are currently in the research and demonstration stage of
development.
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OTEC links |
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Tidal Energy |
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There are basically two
methodologies for creating tidal power: the use of tidal dams or ocean currents.
Dams are based on using a barrage at a bay or estuary with a large tidal range.
Power is generated primarily at ebb tides as the barrage creates a significant
head of water, much like a hydroelectric dam.
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more Tidal Energy links
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Wave Energy |
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Ocean waves are caused by the
wind as it blows across the sea. Waves are a powerful source of energy. The
problem is that it's not easy to harness this energy and convert it into
electricity in large amounts. Thus, wave power stations are rare.
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more Wave Energy links
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