WRITING TASK 1
The diagrams below show the design for a wave-energy machine and its location.
Summarise the information by selecting and reporting the main features and make comparisons where relevant.
You should spend about 20 minutes on this task.
The diagrams illustrates the structure of a system which produces electricity from waves and the locations it can be set up.
As can be seen from the first diagram, the wave-energy machine is constituted of two main chambers linked with each other via two air passages. The turbine is placed in the upper chamber while the lower chamber is partly submerged in the sea wate.
As regards its operation, first, the sea wave enters the lower chamber and raises the water level there to push the air up to rotate the turbine before finding its way out at the top of the system. After that the sea wave withdraws from the lower chamber, which creates a drop in pressure to suck the air back in from the opening in the top chamber to revolve the turbine and come down to the lower compartment of the system. The cycle is then repeated and creates continuous force on the wings of the turbine to make it rotate and generate electricity.
As is shown in the second diagram, the energy generating system can be established close to the shore with smaller waves and lower installation cost accompanied by more modest electricity output. Howerver, when it is erected far offshore where the waves are more powerful, the cost of construction is higher and proportional to the electric yield.
Overall, the diagram presents the working mechanism of a power generating system operating by waves and its possible locations which reveals the positive correlation between the energy output and the installation cost.