IELTS writing task 1-11

The diagram below shows the production of electricity using a system called Ocean Thermal Energy Conversion (OTEC).

Write a report for a university lecturer describing the information below.

Write at least 150 words.

How Ocean Thermal Energy Conversion (OTEC) works

Model answer 1

Ocean thermal energy conversion (OTEC) is a system that converts heat energy into the electric power using the temperature difference between surface seawater, which can be up to 29 degrees Celsius, and deep seawater, which is only 5 degrees Celsius.

The main components of the system are an evacuated evaporation chamber, a turbine and a condensing chamber. The solar energy of the sun heats up the surface water and this warm water is introduced into the evacuated evaporation chamber, where it boils. As it boils, salt is deposited and water vapour is generated. This vapour then drives a turbine to generate electricity. After it powers the turbine, the water vapour enters the condensing chamber, which is cooled by the water from the depths of the ocean. The water vapour is condensed in this chamber, producing drinking water. Meanwhile, waste salt water is discharged into the ocean and the process can be repeated.

Band score 8.5

Model answer 2

The figure demonstrates the process of production of electricity using a system called Ocean Thermal Energy Conversion(OTEC)

Overall in the figure, in elaborates different uses of Natural sources (sea, sun) and other appliances as different kinds of chamber, turbine etc.

Firstly , the sea water is entered with two pipes one at the surface of sea having water temperature nearly about 29 degree whereas other was joined nearly about 600m downwards from sea level. As warm seawater is converted into water vapor by solar energy it is inserted towards evacuated evaporating chamber where salt and vapor is separated. As vapor is lighter in moves towards the pipe connected with turbine which generally moved inside the other chamber. Then, it flowed towards to condensing chamber.

Secondly from the dipper pipe cold water moves with higher pressure and circulates the condensing chamber mixing with salt water separated from Evacuated evaporation chamber and the vapor condensed in chamber creating pure drinking water. Then there is separation of drinking water and waste salt water.

In summary, the OTEC process shows method of filtrating pure water from sea water by using solar energy.

Band score 7.5