Leveraging wave energy

1986/08/01 Ferreres, Iñaki Iturria: Elhuyar aldizkaria

• Energia berriztagarriak

Until now, tidal power plants have been the only way to harness marine energy. However, research has allowed the development of two systems that take advantage of wave energy. Leveraging the energy of the wave can save up to 5% of global energy.

After several years of research, two pilot plants have been built on the seashore in the Norwegian West. Its annual output will be 3.5 million kW.h. The price of this energy is comparable to that obtained with the diesel generator.

On two floors you can see different designs and concepts. These are:

Multiresonant Oscillating Water Column (MOWC).
• Convergent channel.

MOWC Water Oscillating Multiresonating Column

In this system, taking advantage of the force of the waves and channeling the waves, you get a vertical oscillating movement in the water mass in a chamber. The oscillations of this mass generate an alternative air current that acts on the axial turbine associated with an alternator.

This system consists of a concrete box and a tower located above them. So a camera is formed. The turbine is placed on it.

The bottom is open to underwater waves. By introducing the waves they produce a piston effect inside the chamber. Compressed air moves the turbine and when the water column descends, depression occurs and air is taken to remove the turbine.

The axial turbine used is of the type WELES and maintains the direction of rotation, although the air current moves up or down. Thus, the electrical current generated does not need rectification.

The movement of water inside the chamber is governed by the shape of the underwater entrances. A constant amplitude is obtained, although the waves have different continuation frequencies or amplitudes.

When the frequency of the outer waves is different, the oscillation of the inner water column is different. Therefore, the biggest problem and drawback of this system lies in the control of the oscillation of this water column.

Convergent channel

In this system, concentrating the force of the waves in a channel, the water rises to a boat, a few meters above sea level. There the potential energy is collected to convert it into electricity through a hydraulic turbine.

The installation consists of two unique elements. On the one hand, the outer manifold concentrates and captures the incoming direction of the waves and the effect on different frequencies. On the other hand, the convergent channel increases the height of the waves that disperse inland.

In addition to these two elements, a tank and a hydraulic turbine are required.

The outer manifold has a ramal shape and the channel section decreases slowly.

In turn, a wall that forms the channel fulfills the function of dam in the reservoir, accumulating water that exceeds its height.

Using the manifold in a wave width of 55 meters and climbed 3 meters above sea level, 11,000 m 3 accumulate. However, this system can be used in installations of 0.5 to 300 MW.

The conditions of the different places should be measured and each of them should be designed as a collector and channel.