Deep ocean water

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 sufficient to provide a measurable difference in water temperature.

Cold-bed agriculture

A potential indirect use of cold ocean water is "cold-bed agriculture". During condensation or ocean thermal energy conversion operations, the water does not reach ambient temperature, because a certain temperature gradient is required to make these processes viable. The water leaving those operations is therefore still colder than the surroundings, and a further benefit can be extracted by passing this water through underground pipes, thereby cooling agricultural soil. This reduces evaporation, and even causes water to condense from the atmosphere.[4] This allows agricultural production where crops would normally not be able to grow. This technique is sometimes referred to as "cold agriculture"[5] or "cold-bed agriculture".[6]

See also

References

  1. ^ "Ocean Stratification". The Climate System. Columbia University Press. Archived from the original on 29 March 2020. Retrieved 2015-09-22.
  2. ^ "The Hidden Meltdown of Greenland". NASA Science News. NASA. Retrieved 2023-11-27.
  3. ^ "Temperature of Ocean Water". UCAR. Archived from the original on 2010-03-27. Retrieved 2012-09-05.
  4. ^ "Energinat - DOW Technologies - Cold Agriculture". www.energinat.com. Archived from the original on 29 January 2016. Retrieved 14 July 2016.
  5. ^ West Hawaii Tech Pau Hana
  6. ^ "What is OTEC". OTEC News. the OTEC foundation. 30 September 2011. Retrieved 14 July 2016.
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