The world’s first ocean thermal energy conversion (OTEC) unit is now in operation off India’s west coast and producing 1 MW of electrical power.
The ‘power plant’ is housed on a 65 m barge at present anchored 45 miles off the port of Tuticorin, and employs an innovative refrigeration cycle – a so-called ‘reverse’ cycle.
Liquid ammonia is vaporised in an evaporator using surface sea water at 28 °C, and the resulting pressurised vapour used to drive a sophisticated gas turbine to generate electricity. The ammonia vapour is then cooled to the liquid state in a condenser using deep-sea water at7°C, and returned to the evaporator.
The barge housing the Rankine cycle power plant is 68.5 m long,
16 m broad and 4 m deep. The project has been jointly conceived and developed by the National Institute of Ocean Technology, in Chennai, and Dempo Shipbuilding and Engineering of Goa.
"The process, once stabilised, is self-sustaining and continues in an infinite loop," according to Simon Pullokaran, general manager of Dempo. “This is a technology demonstration pilot plant with provision for data collection on all aspects of the design and operation of the process, which would help developing commercial scale plants that can be deployed along the coast providing an eco-friendly, renewable source of electricity."
This pilot plant can generate
1 MWe. Although some of the stages of the process have been tried out separately in laboratory and field conditions by other countries around the world, this is the first time an integrated full-sized plant encompassing the entire process has been built.
The barge has two reservoirs with warm water and cold water compartments to take in the surface and deep-sea water for the plant. The deep-sea water is collected through a 1200 m long pipeline suspended vertically in the sea by means of solid ballast and a mooring buoy. The OTEC barge has one of the deepest single point mooring systems in the world.
The plant was built by Dempo at its Bainguinim shipyard in Goa.
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