Editing Desalination (section)

===Low-temperature thermal===
Originally stemming from [[ocean thermal energy conversion]] research, [[low-temperature thermal desalination]] (LTTD) takes advantage of water boiling at low pressure, even at [[ambient temperature]]. The system uses pumps to create a low-pressure, low-temperature environment in which water boils at a temperature gradient of {{convert|8|-|10|C-change}} between two volumes of water. Cool ocean water is supplied from depths of up to {{convert|600|m|abbr=on}}. This water is pumped through coils to condense the water vapor. The resulting condensate is purified water. LTTD may take advantage of the temperature gradient available at power plants, where large quantities of warm wastewater are discharged from the plant, reducing the energy input needed to create a temperature gradient.<ref name="isope1">{{cite web|last=Sistla|first=Phanikumar V.S.|title=Low Temperature Thermal DesalinbationPLants|url=http://www.isope.org/publications/proceedings/ISOPE_OMS/OMS%202009/papers/M09-83Sistla.pdf|work=Proceedings of the Eighth (2009) ISOPE Ocean Mining Symposium, Chennai, India, September 20–24, 2009|publisher=International Society of Offshore and Polar Engineers|access-date=June 22, 2010|display-authors=etal|archive-url=https://web.archive.org/web/20111004094556/http://www.isope.org/publications/proceedings/ISOPE_OMS/OMS%202009/papers/M09-83Sistla.pdf|archive-date=October 4, 2011|url-status=dead}}</ref>

Experiments were conducted in the US and Japan to test the approach. In Japan, a spray-flash evaporation system was tested by Saga University.<ref>Haruo Uehara and Tsutomu Nakaoka [http://www.ioes.saga-u.ac.jp/VWF/general-review_e.html Development and Prospective of Ocean Thermal Energy Conversion and Spray Flash Evaporator Desalination] {{webarchive|url=https://web.archive.org/web/20120322075415/http://www.ioes.saga-u.ac.jp/VWF/general-review_e.html |date=March 22, 2012 }}. ioes.saga-u.ac.jp</ref> In Hawaii, the National Energy Laboratory tested an open-cycle OTEC plant with fresh water and power production using a temperature difference of {{Convert|20|C-change}} between surface water and water at a depth of around {{convert|500|m|abbr=on}}. LTTD was studied by India's National Institute of Ocean Technology (NIOT) in 2004. Their first LTTD plant opened in 2005 at Kavaratti in the [[Lakshadweep]] islands. The plant's capacity is {{convert|100000|L|abbr=on}}/day, at a capital cost of INR 50 million (€922,000). The plant uses deep water at a temperature of {{convert|10|to|12|C}}.<ref name=irc>[https://www.indiatimes.com/news/india/indian-scientists-develop-world-s-first-low-temperature-thermal-desalination-plant-357286.html Indian Scientists Develop World's First Low Temperature Thermal Desalination Plant]. Retrieved January 1, 2019.</ref> In 2007, NIOT opened an experimental, floating LTTD plant off the coast of [[Chennai]], with a capacity of {{convert|1000000|L|abbr=on}}/day. A smaller plant was established in 2009 at the North Chennai Thermal Power Station to prove the LTTD application where power plant cooling water is available.<ref name="isope1"/><ref>[http://www.headlinesindia.com/archive_html/18April2007_35210.html Floating plant, India] {{webarchive|url=https://web.archive.org/web/20080827213914/http://www.headlinesindia.com/archive_html/18April2007_35210.html |date=August 27, 2008 }}. Headlinesindia.com (April 18, 2007). Retrieved May 29, 2011.</ref><ref>[https://web.archive.org/web/20071031012249/http://www.hindu.com/2007/04/21/stories/2007042109200400.htm Tamil Nadu / Chennai News : Low temperature thermal desalination plants mooted]. The Hindu (April 21, 2007). Retrieved March 20, 2011.</ref>