Interviews |

Dr M A Atmanand I Methods of desalination can convert sea water to potable water

G’nY. What economic benefits does India stand to gain from deep sea mining ? Methods of desalination.
NIOT is developing a crawler based deep sea mining machine which will pick up manganese nodules from a depth of about 6000 m, crush and pump it to the surface ship. Various sub systems like pumping trails, crawler locomotion trials etc. are being executed in a phased manner. Manganese nodules in the Central Indian Ocean Basin (CIOB) contain cobalt (0.2-0.3 per cent), nickel (1-2 per cent), copper (1-2 per cent) and manganese (27-30 per cent). The total estimated quantities of cobalt is 1.82 million tonnes (MT), nickel 10.47 MT, copper 9.5 MT and manganese 247 MT. As the terrestrial resources of cobalt and nickel, which are essential for medical applications and steel respectively, are very limited, it is necessary to mine them from the deep sea bed. At the current metal price, deep sea mining offers a viable proposition .
G’nY. Can India effectively manage coastal areas and check coastal damage?
Coastal erosion throughout India is a massive challenge to coastal engineers. It is necessary to study the shore level change and also the current and wave at a particular location and identify a suitable shore protection measure. There have been knee jerk reactions in finding solutions to coastal erosion, which has led to serious problems in some other locations. It is also necessary to have sustainable protection measures like installation of geo tubes at appropriate locations instead of just dumping tripods and boulders without any scientific study. Shore level changes have been mapped by the National Centre for Coastal Research (NCCR), an institute under MoES. NIOT has successfully done the beach restoration at Pondicherry and shore protection at Kadalur Periakuppam, which is located between Mahabalipuram and Pondicherry in Tamil Nadu. Studies at various other locations like Vizag and Kerala are also underway.
G’nY. There is a rapid decline of freshwater in India. How can we counter this through desalination of seawater?
Oceans can serve as the largest source of freshwater. There are various methods of desalination that can convert seawater to potable water. The technology developed by NIOT is Low Temperature Thermal Desalination (LTTD), which uses the temperature difference between ocean surface and deep sea. Warm seawater from the sea surface is sent to a vacuum chamber where it boils at room temperature, called flash evaporation. The steam thus formed is cooled by deep sea cold water to produce freshwater. This method is environment friendly compared to reverse osmosis plants. The only limitation is that the plant should be located close to deep waters to access the cold water. Three plants working on this principle have been commissioned in the islands of Kavaratti, Minicoy and Agathi in the Lakshadweep. Work is ongoing to set up similar plants in another six islands. The same principle can also be used for thermal power stations where hot water is discharged into the environment. This is being done experimentally at North Chennai Thermal station and is in the offing at Tuticorin. Methods of desalination.
G’nY. What novel instrumentations are being developed by NIOT for ocean observation? How many of these are patented?
Data buoys for ocean observations including tsunami monitoring are indigenised as also are many other observation systems like the autonomous underwater profiling drifter. Some others like drifters are in the process of being indigenised. Patents have been applied for many of them. For sensing of buried objects, a buried object sensing sonar is being developed. Methods of desalination.
G’nY. What innovations developed by NIOT have helped generate employment for India’s populace?
Cage culturing is taken up by NIOT—cages having a diameter of 9 m are anchored to the sea bed and fingerlings are reared in these cages under natural conditions. Training has been offered to fishers in the Andamans, Nellore in Andhra Pradesh and Rameswaram in Tamil Nadu who can now take this up on their own. NIOT will handhold them as and when required. This has helped in generating a new opening for fishers for their livelihood.
G’nY. As renewable energy is becoming important for greening development, how can we tap energy from the oceans?

India being closer to equator has potential for developing Ocean Thermal Energy Conversion (OTEC). As a prelude, an OTEC powered desalination plant is being set up in the island of Kavaratti in Lakshadweep. Offshore wind is also being attempted with Ministry of New and Renewable Energy and private players like Suzlon to set up plants off the coast of Gujarat and Rameswaram. A lot of research is being done to extract wave energy using efficient low wave to electricity converters. Ocean current is another form of ocean energy on which work is done at NIOT. Desalination
G’nY. What is the role of NIOT in Deep Ocean Mission?

NIOT is going to take up large projects as part of Deep Ocean Mission of MoES. One of the important projects being designed is the development and commissioning of a manned submersible in which three humans will be able to go to a depth of 6,000 m underwater. With this India will join the select club of developed countries like USA, Japan, Russia, China etc. who already have
this facility.

NIOT will be continuing its journey in various areas of ocean technology by having more observational platforms, generating ocean energy and freshwater from sea on a larger scale and taking up sustainable coastal protection measures, developing more systems for deep sea work, to bring India at par with the developed countries.

For a detailed report on ocean exploration, technological innovations, Himalayan glaciers, etc: Click here.

Further Reading:

National Oceanic and Atmospheric Administration’s Effort in Combating Ocean Acidification

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