Advances in renewable and clean energy grow every day. It is enough to see the development that wind and solar energy has had in recent years to notice its growing importance as electrical sources. Wave energy, like much of the sea’s energies, has no such drawback.
The wave motor or wave energy comes from the waves. It is produced by taking advantage of its movement, making it a sustainable energy with great potential, because there are waves in all the seas and coasts of the planet. Energy is obtained through the mechanical energy and potential of the sea waves generated by the wind.
Undimotor is another name for wave energy, as its name suggests (undi means “waves” in Greek, and “motor” movement), it is an energy generated by the movement of the waves, and it is used thanks to different technologies.
How wave energy works
Wave energy is produced by electricity generators on the surface of the ocean that take advantage of the movement of the waves. At sea, water flow does not occur in a single direction; but it does always have a top-down movement. The amount of energy is determined by swell height, wavelength and water density.
Types of technologies to capture wave energy
Since the Frenchman Girard patented the first idea to exploit this energy in 1799, multiple technologies have been developed. The main ones are as follows:
Pelanis System
The first of the technologies used in wave motor energy is composed of cylinders and hydraulic joints. The movement of the cylinders relative to others is resisted by the joints, which take advantage of this energy to pump high pressure oil to the accumulators.
Salter Duck
Similar to the previous one. It is a row of wedge-shaped buoys anchored to the seabed. With the movement of the waves, the buoys go up and down as a piston allowing a movement in the air. The air rotates a turbine that produces power.
Point absorbers are vertical devices
That can be fixed directly at the bottom of the ocean or chained to the bottom of the ocean to absorb wave energy from all directions. Electricity is generated using the balancing action of the floating device. This type of fixed device can be used in deeper waters where the energy of the waves is higher.
Overflow devices
Can be fixed or floating structures whose tapered sides are placed perpendicular to the waves. Then the waves flow from the sides to a small reservoir above sea level. Potential water energy is converted into electricity by allowing it to flow through a Kaplan turbine generator and return to the sea.
Motor Wave system
A platform is placed at sea with membranes on the sides that, depending on the swell, expand or contract. The movement expels air and moves a turbine.
The Oyster
A clam-shaped machine is anchored to the sea bottom 10 meters above surface level. The arm opens and swings like a pendulum in response to sea movement.
An oscillating water
Column or buoys is a natural cave with a blow hole or artificial chamber with a wind turbine generator on the surface of the water. It is fixed directly on the coast, perpendicular to the waves. The waves result in a vertical oscillation of water within the chamber that acts as a piston in the air over the water. Compressed and decompressed air flows through the wind turbine generator and produces electricity.
Advantages and drawbacks of wave motor energy
Wave motor energy has great advantages, such as the production of electrical energy without emitting polluting gases into the atmosphere, generating minimal environmental impact, both visual and sound, since it does not require large installations. The sea also gives us the possibility of obtaining this energy for free, inexhaustible and constant. Most of this energy can be found in the Atlantic and Pacific Oceans.
Despite these great advantages, it has the disadvantage of requiring large investments for installation and maintenance. These costs will increase when you do the distance to the coast.
Sometimes wave motor energy is confused with the energy of tides, without being the same. The energy of the waves, obtains the electrical energy from the mechanical energy that causes the movement of the waves. However, the energy of the tides generates this energy from the movement of the tides.
Other Difficulties
The absence of a constant frequency and altitude in the waves is one of the main difficulties in obtaining this type of energy. Another difficulty is that not all coastal areas are adequate or have the conditions for the facilities. In addition, the challenge of installing equipment in the ocean is maintained, as it requires high investments and the saline environment is hostile to the devices.
Environmental effects
Plants near the shore that are visible from land can cause conflicts with tourist interests or with the acceptance of local populations. Because of this, the facilities must undergo a rigorous study to minimize impacts to the environment and find the optimal size and location.
Great maintenance
Almost all parties involved in the facilities to harness the energy of the waves require regular maintenance, as the salinity of the seawater is well invasive. And this once again results in costs.
Break with the seascape. Although their structures are not as invasive, they remain alien to the marine and coastal world.
On today, there are some projects that have opted for wave motor energy. However, experts agree that it has not been optimally developed. This energy source requires a lot of research to achieve a design and therefore a lot of investment.
Successful cases
There are some successful cases that use wave motor energy as an electrical source. The most emblematic are in Scotland and Norway. In Scotland is the Limpet plant, with OWC technology. Located on the coast, the structure has an air chamber at the top, while the lower one is open to the action of the waves.
A Waves4Power facility is available in Norway on Runde Island. This is a unique system that allows energy to be achieved through a gigantic buoy. The buoy has a vertical tube with openings at both ends and functions as a water pump. A piston is activated by the movement of the waves and produces electricity.
In Australia, off the coast of Perth, there is also an wave motor power plant, with a buoy mechanism. This plant supplies power to the Australian Department of Defense and its naval base.