Ocean thermal energy conversion
Also called: OTEC · Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Beyond NCERT
Meaning
Ocean thermal energy conversion (OTEC) makes electricity from the difference in temperature between warm surface seawater and cold deep seawater. The gap needs to be about 20°C. The warm water heats a fluid until it turns to vapour, and the vapour turns a turbine. The cold deep water then cools the vapour back to a liquid, and the cycle repeats. It suits tropical seas, where the surface stays warm all year. It can give steady power to islands that are far from the mainland grid.
Example
The National Institute of Ocean Technology (NIOT) is building a demonstration OTEC plant at Kavaratti in Lakshadweep, in the Arabian Sea.
Don't confuse with
- Tidal energy: uses the rise and fall of tides. Water is trapped behind a floodgate dam and released through turbines. The best Indian sites are the Gulfs of Khambhat and Kachchh and the Sundarbans. OTEC uses differences in heat, not the movement of water.
- Geothermal energy: uses heat from inside the earth, not from the sea.