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[clarification needed] sufficient to provide a measurable difference in water temperature.
Cold-bed agriculture
[edit]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
[edit]
References
[edit]- ↑ "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. 27 August 2015. Retrieved 2023-11-27.
- ↑ "Temperature of Ocean Water". UCAR. Archived from the original on 2010-03-27. Retrieved 2012-09-05.
- ↑ "Energinat - DOW Technologies - Cold Agriculture". www.energinat.com. Archived from the original on 29 January 2016. Retrieved 14 July 2016.
- ↑ "West Hawaii Tech Pau Hana". Archived from the original on 2022-01-31. Retrieved 2016-07-14.
- ↑ "What is OTEC". OTEC News. the OTEC foundation. 30 September 2011. Archived from the original on 23 February 2020. Retrieved 14 July 2016.
