National Institute of Ocean Technology (NIOT) – Desalination Plant In Lakshadweep

Stepping up from its ongoing initiative of providing potable water in six islands of Lakshadweep using Low Temperature Thermal Desalination (LTTD) technology, the Chennai-based National Institute of Ocean Technology (NIOT) is working at making this process free of emissions.

What is Low Temperature Thermal Desalination (LTTD) technology?

  • It is based on Ocean Thermal Energy Conversion (OTEC) principle.
  • It is one process that uses the availability of a temperature gradient between two water bodies or flows to evaporate the warmer water at low pressure and condense the resultant vapour with the colder water to obtain freshwater.
  • While ocean, with its temperature variation across its depth, presents one such scenario of two water bodies, a coast based thermal power plant discharging huge amounts of condenser reject water into the nearby ocean represents an alternate scenario.

Note: Near Lakshwadeep there is a difference of about 15 – 20 degree Celsius between sea surface water and deep sea water.

image 40
  • Warm surface sea water is flash evaporated at low pressure and the vapour is condensed with cold deep sea water.
  • LTTD exploits the difference in temperature (nearly 15°C) in ocean water at the surface and at depths of about 600 feet.
  • This cold water condenses water at the surface, that is warmer but whose pressure has been lowered using vacuum pumps.
  • Such de-pressurised water can evaporate even at ambient temperatures and this resulting vapour when condensed is free of salts and contaminants and fit to consume.

Note: Sea water is salty. When water evaporates, it leaves the salts behind. Those vapours when get condensed, are transformed into pure fresh water.

image 41
  • The LTTD technology does not require any chemical pre and post-treatment of seawater and thus the pollution problems are minimal and suitable for island territories.
  • Since no effluent treatment is required, it gives less operational maintenance problems compared to other desalination processes.
  • The LTTD technology is completely indigenous, robust and environment friendly.
  • The cost per liter of desalination would depend on the technology used and cost of electricity which varies from place to place.

Existing issue: Currently the desalination plants, each of which provides at least 100,000 litres of potable water everyday, are powered by diesel generator sets — there being no other source of power in the islands. However, the need for diesel power to reduce the water pressure means that the process is not fossil-fuel free and also consumes diesel, a precious commodity in the islands that has to be shipped from the mainland critical for powering the electric grid.  

Leave a Reply

Your email address will not be published. Required fields are marked *

The maximum upload file size: 20 MB. You can upload: image, document, archive, other. Drop files here

Online Counselling
Today's Current Affairs
This is default text for notification bar