Ocean Thermal Energy Conversion (OTEC)

Ocean Thermal Energy Conversion (OTEC)

• Ocean thermal energy conversion (OTEC) is a source of renewable energy.

• Ocean Thermal Energy Conversion (OTEC) makes use of the naturally occurring thermal gradient of the oceans.

• The warm water acts as a heat source whilst the cold water at about 1000 m acts as a heat sink. This creates a thermal power cycle which can be used to generate electricity.

• The minimum difference required between the heat source and the heat sink is 20 °C.

• The efficiency of OTEC is very low (< 4 %) but the enormous magnitude of this potential energy resource merits its investigation.

• In addition, OTEC could provide a continuous energy supply, unlike many other renewable technologies.

1. Advantages of OTEC System

1. Power from OTEC is continuous, renewable and pollution free.

2. Unlike other forms of solar energy, output of OTEC shows very little daily or seasonal variation.

3. Drawing of warm and cold sea water and returning of the sea water, close to the thermocline, could be accomplished with minimum environment impact.

4. Electric power generated by OTEC could be used to produce hydrogen.

5. Tropical and sub-tropical island sites could be made free from pollution caused by conventional fuels for electricity generation.

6. OTEC system might help in enrichment of fishing grounds due to the nutrients from the unproductive deep waters to the warmer surface waters.

7. A floating OTEC plant can generate power even at mid sea and can be used to provide power for off shore mining and processing of manganese nodules.

2. Limitations of OTEC System

1. Capital investment is very high.

2. Due to small temperature difference in between the surface water and deep water, conversion efficiency is very low about 3-4 %.

3. Low efficiency of these plants coupled with high capital cost and maintenance cost makes them uneconomical for small plants.