When the wind blows, it hits the surface of the ocean by propagating mechanical waves, more and less marked according to its force (wind): This is where the waves are created. Recently, it has been discovered that we can exploit the extraordinary potential of these waves and convert them into energy. So how can this promising wave energy be exploited?
It is renewable marine energy, also known as wave energy, which gets its name from the fact that it is produced from swells; which are waves that follow one another on the sea surface under the effect of the wind and which are sometimes propagated over large distances in the absence of obstacles.
Starting from the principle that the swell, as a source of energy, is free, inexhaustible and non-polluting, several devices have been put in place to recover it and subsequently convert it into electricity, and among these devices, the following three main systems have been put in place:
– The articulated floating chain: This is the best-known process using wave energy. It is a floating articulated structure perpendicular to the waves, made of steel pipes containing hydraulic pumps. The movement of the waves forces the hydraulic liquid to drive a turbine that feeds a generator producing electricity; this system is initially tested in Portugal, with a power of 750 kW, consisting of 5 articulated floats and weighing 1,350 tons.
– Oscillating water columns: A pivoting system driven by the orbital movement of the water as the waves pass, which in turn drives a turbine that can work in both directions. This type of device can be installed at sea or on the coast. It was tested ” OYSTER ” in Scotland in 2009 with a power of nearly 300 kW.
– The surge trap: It retains water from wave crests, creating excess pressure in the reservoir. The volume of water trapped is turbines.
According to the World Energy Council, 10% of the world’s electricity consumption could be covered by wave energy each year, and as we have seen, the techniques for exploiting wave energy are numerous, and they face several problems such as:
– Installation and maintenance work, especially off-shore, presents many technical constraints and high costs.
– The installation of these systems has a disastrous impact on the environment: Disfiguring the coastal landscape and the disappearance of marine fauna and flora.
– The strong corrosion due to seawater of the materials used.
– The problems of the fragility of the materials related to a very agitated marine environment.
In conclusion, operating systems are still in their infancy and therefore have many constraints, but some studies estimate that the efficiency of wave energy could be higher than that of wind power.