Fresh water from sea
India commissions first-ever offshore desalination plant
http://www.tribuneindia.com/2007/20070419/nation.htm#5
Vibha Sharma
Tribune News Service
New Delhi, April 18
In first-ever project of its kind in the world, India has successfully managed to commission an off shore barge-mounted desalination plant of one million litres per day(MLD) capacity using completely indigenous high-capacity low temperature thermal salination technology to produce freshwater from seawater.
Minister of Earth Sciences, Kapil Sibal, today said the plant was a forerunner to similar plants of higher capacity that could be set up in public private partnership (PPP) along the vast Indian coastline using the same low-cost technology to solve the country’s water woes in the future. The single point mooring of 1000 m at the barge was the first of its kind in the world, the minister said.
Population growth along with limited fresh water sources has made good quality water a precious commodity. Considering the fact that the Inter-governmental Panel on Climate Change’s latest assessment report predicted the gross per capita water availability to drop by almost 38 per cent by 2050, declining from 1820 cubic meter at present to 1,000 cubic meter, this low cost method can become an answer to challenges posed by imminent climate change and global warming.
“Following some more improvisations, we expect to be ready with the entire technology early next year and bring in private players to set up desalination plants of higher capacity along the coast for the use of common people, ” he added.
The Chennai-based National Institute of Ocean Technology (NIOT) has mounted the project at the Sagar Shakti barge, 40 km off the Chennai shore, using the in-house technology which is much cheaper to run than the conventional reverse osmosis technology used elsewhere in the world.
Other countries to have developed technologies to make salty sea water drinkable, include Israel, US and Dubai. They, however, use a different technology-reverse osmosis, which is much more expensive option. The indigenous technology will cost three paise per liter in the long run and its power consumption is 3.5 kw/hour. Compared to reverse osmosis which uses eight to 10 kw/ hour, it is a much cheaper option.
Under the process warm surface seawater is flash evaporated at low pressure and vapour is condensed with cold deep seawater. The water is transported to Chennai using water bags of special material that can hold and carry 2 lakh liters of fresh water. Since fresh water is lighter than the seawater, it floats and a small fishuing boat can tow the water bag to the shore.
Sibal said, NIOT managed to produce purest of pure water using the technology. The freshwater produced by NIOT has a TDS of less than 10 ppm. The accepted standard is 500 ppm whereas the BIS permits a ppm of 2000.In India, so far NIOT has indigenously designed, developed and demonstrated the desalination technology that can produce about one-lakh litre of fresh water from sea water per day. A one-lakh litre per day capacity LTTD plant was commissioned in May 2005 at Kavaratti, one of the Lakshadweep islands.
IIRC even Pakistan has desalination plant programme, what is the status?
