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Technology Projects > Ocean Structures > Activities

A. LTTD Plants in islands

MoES-NIOT is extending technical support for the issues related to the LTTD plants commissioned at Agatti, Minicoy and Kavaratti and proposal to install similar plants in six more islands.

Setting up of LTTD Plants in Six Islands of UT Lakshadweep

Back ground:
Lakshadweep islands are remote, facing drinking water scarcity due to increased population and tourism activities. MoES-NIOT has developed Low Temperature Thermal Desalination (LTTD) technology and established the plants at Kavaratti (2005), Minicoy and Agatti (2011). The produced fresh water is being supplied continuously to local communities since commissioning of the plants. The major technical challenges include site specific design and installation of 950m long pipeline to draw cold water from 350m depth and marine structure to draw cold/warm water and to support the pipe line. As the sea bed topography and environment are different in each island, the design of marine structures and cold water pipe was prepared considering site specific conditions of respective island. All marine structures and cold water pipe are performing well even during extreme environmental conditions. Performance enhancement studies conducted on the deaerator efficiency and the vapour flow inside the flash chamber were carried out. The findings from these studies are considered in the Detailed Project Report (DPR) submitted to UT Lakshadweep Administration for setting up the six more LTTD plants (Amini, Androth, Chetlat, Kadamat, Kalpeni and Kiltan).

Ministry of Earth Sciences has taken responsibility of overall project from design to commissioning including tendering and administrative approval for the project through National Institute of Ocean Technology. Contracts were awarded through national bidding processes and initiated the implementation activities at islands.

Progress:

MoES-NIOT initiated the implementation activities at islands after awarding the contract.

• The contract for the Establishment of LTTD plants in Amini, Kadamat, Chetlat, Kalpeni, and Kiltan Islands were executed during April 2018 and for Androth during October 2018..
• The Conceptual and detailed design submitted by the contractors for all the six Islands were reviewed and approved for execution during November/December 2018..
• Subsequent to the approval of design, Men and materials were mobilized and work has commenced in the Islands..
• Kalpeni LTTD plant was commissioned and fresh water was obtained on 9th January, 2020.
• The construction activities on remaining islands, namely, Amini, Androth, Chetlat, Kadamat and Kiltan Islands is in progress.

Marine Structures, Kalpeni

Marine Structures, Amini

B. Ocean Structures

Development of Technologies for offshore structural components:

Design of the Offshore reef with beach nourishment for coastal protection at Puducherry
Feasibility studies on fixed and floating platform for offshore wind turbine.
Estimation of wave forces (breaking & non-breaking) through wave structures interaction studies.
Analysis, Design, model studies of Fixed and Floating Platform components such as Mooring, risers and connections to floating bodies for offshore structures.

(a) Design of the offshore reef with beach nourishment for coastal protection at Puducherry

Back ground:

The coastline of Puducherry has suffered from severe coastal erosion due to natural and anthropogenic activities. Initially, sand bypassing was carried out by harbor authorities to prevent down drift erosion and to maintain channel free from siltation. Later, discontinuing sand bypassing due to various technical reasons, lead to erosion on Puducherry city. Puducherry government has implemented sea walls and Groynes at various timelines to mitigate the problem which protected the coastal infrastructure but erosion shifted further north.
Shore line management plan was submitted to Pondicherry government and Pilot Beach nourishment was also recommended on the north of Puducherry harbour. Puducherry government has implemented the beach nourishment scheme, which showed a gain of beach to an extent of 60m. The newly formed beach received positive response from local population and Puducherry government requested ESSO-NIOT to restore the lost beach near Gandhi Statue area of Puducherry. Numerical models were constructed to study the shoreline response for beach nourishment with various configurations of retaining structures. Based on these results a northern nearshore reef and southern offshore reef along with beach nourishment was recommended. The Northern reef is proposed to be implemented by MoES-NIOT on pilot basis and Southern Reef along with Beach Nourishment is being taken up by the Puducherry Government.
The process of preparation of seabed for laying the stone base on which the steel reef will be placed is completed.         Detailed methodology, considering the prevailing site conditions, has been worked out for base layer preparation and is being executed. On the working platform, the construction of the wedge shaped steel reef has been completed. The bottom of the wedge reef, in the shape of a triangle with a base width of 50m and a length along the spine of 60m, has been completed. Successfully launched appx.900 ton wedge shaped steel reef into the open sea, positioned and ballasted.

Progress:
The changes in shore line, beach profiles and hydrodynamics are being monitored at regular intervals.
A workshop for officials of Puducherry Government was conducted by NIOT to improve their understanding of the project.
Hon'ble Minister of Earth Sciences attended a public event at project site and dedicated the restored beach to the public.

Puducherry beach restoration Project

 

(b) Feasibility Studies on Platform for Fixed and Offshore Wind Turbines

Back ground:

Offshore wind being pollution free would be an ideal solution to meet this increasing demand as Indian coast is blessed with significant winds. The promising factors for offshore wind development are i) Strong / Consistent winds compared to land, ii) Less sound pollution and visual intrusion, iii) Best benefit to coastal areas due to less transmission cost, iv) Exploitation of available onshore wind sites and v) Easy transportation of Larger Capacity Turbines.

Wind resource assessment results show high potential at Kanyakumari followed by Rameshwaram and Jakhau. Turbines with 3 MW capacities perform at high Plant Load factor at all the 3 locations along Indian coast when compared with other commonly available turbines in the range of 1.5 to 5MW. Oceanographic parameters were obtained through numerical modeling and Geotechnical investigations were performed at potential sites along Gujarat coast. Preliminary design of substructure by exploring different concepts like Monopile, Jacket and Gravity based foundations was carried out based on their suitability for site specific environmental and soil data at potential locations.

• The Lidar based data collection platform at Gulf of Khambhat has been successfully installed during March, 2017 and various meteorological parameters like wind speed, direction, temperature and humidity are continuously being measured.
• The platform at Gulf of Kutch has been successfully installed during October, 2017 and various meteorological parameters are continuously being measured.
• Data is being collected from both the platforms since April 2017/October 2017. Monthly average wind speed of about 8.3m/s at 20m elevation from sea level has been observed at Gulf of Khambhat
• National Institute of Wind Energy (NIWE) proposes to develop a demonstration offshore wind farm with the capacity of 30 MW off Dhanushkodi coast and requested NIOT to provide details of Wave climate, Tides, Tidal range, currents, earthquake, soil characteristics, maps of protection zones, wind resource, detailed Logistic study, power evacuation study and suitable substructure design and its installation methodologies etc

Analysis of Offshore Support Structure for Wind Turbines and Data Platforms

Progress:

• Offshore wind data is being collected continuously at both locations in Gulf region and NIWE is in the process of data analysis.

(c) Wave structure interaction studies

Back ground:

The response of ocean structures to hydrodynamic forces (wave and currents) is nonlinear and complex. The existing standards do not have reliable methods to estimate wave forces on coastal structure. Wave Structure interaction studies were taken up to address such needs and the method to estimate forces on structures through full scale experiments and Numerical Modelling. A Full scale experiments are being conducted on intake structure at Agatti Island, where wave and tidal measurements have been recorded since March 2012 to till date by bottom mounted directional wave recorders which measures both incident and reflected waves. An extensive array of pressure transducers is fixed on the intake structure to measure the incident wave pressure. Standardization for estimation of wave loads on marine structures and development of numerical tools for estimation of wave loads is in progress.

Progress:

• Based on the inputs from the studies, Indian Road Congress is in the process of evolving guidelines for estimation of wave loads on structures, for which a sub-committee was constituted with MoES-NIOT coordinating the activities. Long term field measurements were also requested.