Cold, salty water deep below the surface of Earth's oceans
Deep ocean water (DOW) is the name for cold, salty water found in the deep sea, starting at 200 m (660 ft) below the surface of Earth's oceans. Ocean water differs in temperature and salinity. Warm surface water is generally saltier than the cooler deep or polar waters;[1] in polar regions, the upper layers of ocean water are cold and fresh.[2] Deep ocean water makes up about 90% of the volume of the oceans. Deep ocean water has a very uniform temperature, around 0–3 °C (32–37 °F), and a salinity of about 3.5% or, as oceanographers state, 35‰ (parts per thousand).[3]
In specialized locations, such as the Natural Energy Laboratory of Hawaii, ocean water is pumped to the surface from approximately 900 m (3,000 ft) deep for applications in research, commercial and pre-commercial activities. DOW is typically used to describe ocean water at sub-thermal depths[clarify] sufficient to provide a measurable difference in water temperature.
When deep ocean water is brought to the surface, it can be used for a variety of things. Its most useful property is its temperature. At the surface of the Earth, most water and air is well above 3 °C. The difference in temperature is indicative of a difference in energy. Where there is an energy gradient, skillful application of engineering can harness that energy for productive use by humans.
The simplest use of cold water is for air conditioning: using the cold water itself to cool air saves the energy that would be used by the compressors for traditional refrigeration. Another use could be to replace expensive desalination plants. When cold water passes through a pipe surrounded by humid air, condensation results. The condensate is pure water, suitable for humans to drink or for crop irrigation. Via a technology called ocean thermal energy conversion, the temperature difference can be used to run a heat engine to generate electricity.
^"Ocean Stratification". The Climate System. Columbia University Press. Archived from the original on 29 March 2020. Retrieved 2015-09-22.
^"The Hidden Meltdown of Greenland". NASA Science News. NASA. Retrieved 2023-11-27.
^"Temperature of Ocean Water". UCAR. Archived from the original on 2010-03-27. Retrieved 2012-09-05.
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surface water is generally saltier than the cooler deep or polar waters. In polar regions, the upper layers of oceanwater are cold and fresh. Deepocean water...
sink into the deep sea basins and spread in entire deepocean by the thermohaline circulation. Upwelling of cold water from the deepocean is replenished...
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a decline in mixing of the ocean layers, so that warm water stabilises near the surface. A reduction of cold, deepwater circulation follows. The reduced...
Mackenzie), the water of which quasi floats on the saltier, denser, deeperoceanwater. Between this lower salinity layer and the bulk of the ocean lies the...
65% of the ocean's completely open water. The oceanic zone has a wide array of undersea terrain, including trenches that are often deeper than Mount Everest...
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