Sources of energy : The sea, a power to exploit

The seas of the world, whatever their nature, Authorized or prohibited, in harmony with the oceans, constitute significant potential to be exploited for the supply of energy sources. This is marine energy, thalasso-energy, or even blue energies which promote the production of electricity thanks to the various resources of the marine environment.

While global electricity consumption is approximately 16 000 TWh/an, the seas and oceans have the potential to produce electricity in an inexhaustible way, with a theoretical energy potential of up to 100 000 TWh/an. So, the seas, in harmony with the oceans, given their capacity and scope, constitute a huge source of renewable energy thanks to the physicochemical properties of water.

“Marine energies are a form of exploitation of renewable resources from the marine environment. They understand the tides, the currents, waves, the heat, salinity, biomass and winds”, explains Zacharie Sohou, oceanographer, professor and Director of the Fisheries and Oceanological Research Institute of Benin (IRHOB). According to his explanations, there are a variety of marine energies, notably the energy of offshore winds, coming from the winds released by the sea, tidal energy which exploits tidal currents, tidal energy from marine or river currents. There is also wave energy, which comes from sea waves, thermal energy from the seas (ETM) or tidal energy, which results from the variation in ocean temperature between surface waters and deep waters, and finally osmotic energy, which exploits the heterogeneity of salinity between seawater and freshwater.

Offshore wind energy, also called offshore wind turbine, is a source of energy dependent on wind. “The sun heats the earth unevenly, thus creating zones of different temperatures and atmospheric pressure around the globe. From these pressure differences arise air movements, called wind. This energy makes it possible to produce electricity in wind turbines, also called wind turbines, thanks to the force of the wind, explains Zacharie Sohou. “There are two main types of offshore wind turbines. Fixed wind turbines, located on the seabed less than 50 meters deep, and floating wind turbines, built on land and installed in areas where the depth of the seabed exceeds 50 meters », he adds. Regarding tidal energy, it is generated by the movements of water created by the tides under the combined effect of the gravitational forces of the moon and the sun. It can be used in the form of potential energy, through sea level rise, or in the form of kinetic energy, by exploiting tidal currents. Tidal energy, as for her, consists of a hydraulic turbine (underwater or floating) which uses the kinetic energy of marine or river currents, similar to how a wind turbine uses the kinetic energy of the wind.

Wave energy, or sea wave energy, harnesses the power of swell wave movement. It is essential not to confuse marine wave energy with tidal energy, which uses tidal energy. Thermal energy from the seas (ETM) or tidal energy is produced by exploiting the temperature difference between the surface waters and the deep waters of the oceans. We often encounter the acronym OTEC, pour «Ocean thermal energy conversion».

Finally, osmotic energy relies on the potential to obtain energy near estuaries, where fresh water from rivers mixes with salt water from the sea. It exploits the phenomenon of osmosis which occurs continuously at the level of an appropriate membrane separating masses of water of different salinity, as the oceanography professor explains.

Successful and green renewable energy in turn

“Renewable energy” most of the time uses solar panels, wind turbines or even geothermal energy. But energy from the sea and ocean is the most efficient and sustainable. Thereby, Marine energy is one of the most abundant renewable energy sources on the planet”. Renewable energies are inexhaustible sources of energy and available in unlimited quantities. Since renewable energies are generally clean and produce no or very few polluting emissions and thus contribute to the reduction of greenhouse gases in the atmosphere, marine energies are sources of energy suitable for promoting. So, marine energies constitute a “green” energy source, respectful of the environment.

Setbacks

Although marine energies offer an exhaustive list more for the planet because they are more ecological than the fossil and fissile energies currently exploited throughout the world, However, they have setbacks, particularly on the marine ecosystem.. “Large underwater machines to produce wave energy can disrupt the peace of wildlife. We fear that these devices will disturb the seabed and creatures close to the shore such as crabs or starfish,” underlines the oceanographer..

As well, Can noise emissions generated by construction and maintenance operations be detrimental to the well-being of marine mammals?. It should be noted that marine energies have “a relatively high cost for the purchase of installations whose profitability can take years to come.”, intermittency of production and dependence on the weather for certain renewable energy sources such as wind and solar energy” confides expert Zacharie Sohou. Thus, marine energy is a significant ecological footprint for certain renewable energy sources such as biomass. The exploitation of seas and oceans as an energy source is very beneficial for the planet in the sense that its advantages far outweigh the disadvantages.. However, marine energy is not only hydraulic as many people believe. The seas and oceans offer a fairly considerable and vital margin of maneuver in terms of energy sources. It is therefore up to the United Nations to work for a policy that respects the environment and marine spaces so that marine energies are more integrated into the daily lives of all humanity to achieve the objectives in favor of carbon neutrality..

Note that there is a difference between sea and ocean. The oceans are larger than the seas, but the seas are full of the greatest biological diversity. Moreover, seas are saltier than oceans and exist in three forms. We arrange the Mediterranean seas, the closed seas and the Inland seas.

Christelle DJOMAMOU (Jupiter)