The Ministry of Earth Sciences, along with the Tamil Nadu Government, will set up a 10 MLD low temperature thermal desalination plant about 40 km from Chennai, said Union Secretary of the Ministry of Earth Sciences, Shailesh Nayak.
Talking to City Express on the sidelines of Chemtech South 2013, Nayak said that a detailed project report is being prepared by Larsen and Toubro and the National Institute of Ocean Technology (NIOT) to set up this barge mounted desalination plant. This is a joint initiative by the Ministry of Earth Science and the Tamil Nadu government, he said. The main purpose of the plant is to meet the drinking water requirements of the city. He said the operating cost of producing per litre of water is 19 paise.
He said it would take nearly 18 months to get the DPR ready. The move comes in the wake of four low temperature thermal desalination plants being commissioned in the country.
Usually, in this technology, warm water is flashed inside a vacuum flash chamber and the vapour produced is condensed using cold water.
The temperature difference that exists between the warm surface sea water (28 to 30 degrees celsius) and deep sea cold water (7 to 15 degrees celsius) would be effectively utilised to produce potable water.
Nayak said the thermal desalination plant does not affect the marine eco-system unlike the regular desalination plants, which let out brine. Nayak also said that the thermal desalination plant in Tuticorin would be ready in the next two to three years. This will provide two million litres of water per day, he said.
Four Low Temperature Thermal Desalination (LTTD) plants have been successfully commissioned in the country at Kavaratti (2005), Minicoy (2011), Agatti (2011) islands of Lakshadweep and at North Chennai Thermal Power Station (NCTPS), Chennai (2008). The capacity of each of these LTTD plants is one lakh litre of potable water per day. The capital cost of the LTTD plant at Kavaratti was Rs 5 crore, at Minicoy Rs 13 crore, at Agatti Rs 21 crore, and at NCTPS, Rs 5 crore.