CHENNAI: With thermal power plants being the largest industrial users of water and exceedingly contributing to water-stress, Chennai-based National Institute of Ocean Technology (NIOT) has come out with a novel concept of using coolant water discharge from power plants to produce fresh water.
Thoothukudi Thermal Power Station will be the first in the country to have an in-house 2 MLD (million litres per day) desalination plant based on Low Temperature Thermal Desalination (LTTD) technology. This assumes significance as the Thoothukudi power plant is constantly accused of depleting the Tamirabarani water by drawing fresh water from the Srivaikuntam dam.
NIOT director MA Atmanand on Thursday revealed that the institute has already called for tenders and when successfully implemented, would be a model for other coastal thermal power plants to emulate. In India, almost 90% of thermal power generation depends on freshwater, which is used for cooling of power plants. But, much of that water is lost as clouds of vapour. However, the LTTD process uses the temperature variation between warm water discharge and surface sea water to condense the water vapour to produce fresh water.
Scientists at NIOT have tailor-made the 2 MLD desalination plants in such a way as to generate 1 MLD of safe drinking water and another 1 MLD of pure distilled water meant for industrial use at Thoothukudi power plant.
MoES secretary M Rajeevan Nair and NITI Aayog member VK Saraswat have hailed the project as ‘’game changer’’ at a conference on Technologies for Renewable Energy and Water, which got underway at NIOT on Thursday. Purnima Jalihal, Head (energy and fresh water group), NIOT, told Express that tenders were floated on March 5 and the project would approximately cost `40 crore.
“LTTD technology had been used successfully in the projects implemented in the Lakshadweep Islands. The novelty here is it has been fine-tuned to suit power plants’ need. Before this, an experimental plant generating 2-3 lakh litres per day was demonstrated at North Chennai Thermal Plant,” she said. She said thermal power plants discharge large quantities of warm water, which was an environment threat. The conventional desalination processes such as reverse osmosis leave behind high concentration of membrane which again contributes to environment degradation.
NITI Aayog member Saraswat said technologies such as these are critical for long-term sustainability. “Energy and water are important for the country’s growth and to generate energy we need water, which is becoming scarce due to various factors. So, how to meet energy demands without putting too much of stress on water resources. Processes like LTTD are the answer.”
He said according to a report by World Resources Institute (WRI), 40% of the country’s thermal power plants are located in areas facing high water stress and 50% of thermal power plants will face difficulties by 2030, owing to water deficit.
How LTTD works
LTTD works on the principle of utilising temperature gradient between two water bodies to evaporate the warmer water at low pressure and condense the resultant vapour with the colder water to obtain freshwater.