The following points highlight the four devices used for conversion of wave energy. The devices are: 1. Hydraulic Accumulator Wave Machine 2. High Level Reservoir Wave Machine 3. The Dolphin Type Wave Power Machine 4. Dam-Atoll Wave Machine.
1. Hydraulic Accumulator Wave Machine:
The machine consists of the following main components:
i. Pressure Amplifier:
The waves enter the cylinder of pressure amplifier at the bottom and move the main piston. The pressure of the closed loop fluid is amplified to about 5 bars.
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ii. Hydraulic Accumulator:
The high pressure fluid is conducted through a one-way up valve to a hydraulic accumulator. The accumulator has air cushions on the top which assists in maintaining a constant pressure.
iii. Pelton Turbine:
Part of high pressure fluid flows through a Pelton wheel or Francis hydraulic turbine that drives an electrical generator.
On the trough of the wave, the composite piston is pushed downward by the high fluid pressure. The exhaust water is sucked via return valve. The capacity of hydraulic accumulator is large enough to permit continuous turbine operation though the waves are cyclic.
2. High Level Reservoir Wave Machine:
It also consists of pressure amplifier which sends high pressure water to a high level reservoir on a shore line. The potential energy of water in the reservoir is used to run a water turbine coupled to an electrical generator.
3. The Dolphin Type Wave Power Machine:
The major components of the system are a dolphin, a float, a connecting rod and two electrical generators (Fig. 7.54).
The float has two motions. The rolling motion about its own fulcrum with the connecting rod is amplified and converted into continuous rotary motion with the help of gears. The electrical generator is driven. The other vertical motion is also amplified and converted into rotary motion to drive the gears.
4. Dam-Atoll Wave Machine:
The waves wrap themselves around the atolls (small volcanic islands) from all sides, producing a spiral in the centre. A turbine is driven when water is discharged radially outward.