Marine energy It is one of the least exploited forms of renewable energy in the world today. However, the oceans and seas possess an immense energy potential that, if properly used, could satisfy a significant part of the world's electricity demand. This form of energy has multiple sources, such as waves, tides, marine currents, thermal gradients and salinity gradients. Despite its advantages, its development has been slow due to the high cost and associated technological challenges.
Types of marine energy
There are several ways to take advantage of the marine energy, each with its own technologies and challenges. Here we detail the main ones:
Wave energy
Also known as wave energyThis form of marine energy is obtained by taking advantage of the movement of waves on the ocean surface. Waves are generated by the action of wind on water, and since wind is generated by solar radiation, we can consider wave energy as a derivative of solar energy.
Waves contain a large amount of kinetic energy due to their oscillatory motion. Some areas of the planet, particularly those with constant winds, have considerable potential to harness this type of energy. For example, in regions of the North Atlantic Ocean, the energy contained in waves can reach up to 70 MW per square kilometre.
There are different technologies for capturing wave energy. Devices such as the following stand out: oscillating water columns, dimmers to floating terminatorsThese mechanisms transform the movement of waves into useful energy through turbines or hydraulic systems.
Tidal energy
La Seawater energy It is generated by taking advantage of the rise and fall of the water level produced by the tides, which are caused by the gravitational attraction of the sun and the moon on the oceans. This phenomenon, which occurs in a predictable manner, makes tidal energy a very reliable source.
The main systems used to capture tidal energy involve building dams in coastal areas where the water level changes significantly with the tides. When the dams are opened, the water passes through turbines, generating electricity.
A notable example of the use of this technology is the La Rance tidal power plant in France, which has a capacity of 240 MW.
Energy of ocean currents
The Ocean currents They are movements of water masses that occur in the oceans due to the action of the wind and other geophysical factors. To take advantage of the kinetic energy of these currents, underwater turbines similar to wind turbines are used, but adapted to the aquatic environment.
The main challenge for the development of this technology is the irregularity in the speed of ocean currents, as well as the technical and economic difficulty of installing and maintaining the turbines on the ocean floor.
Thermal gradients
La thermal gradient energy It is based on taking advantage of the temperature difference between surface waters, which are heated by solar radiation, and deeper waters, which remain cold. This phenomenon occurs in tropical or equatorial regions, where the thermal gradient between the surface and the depths of the ocean is significant throughout the year.
To transform this energy into electricity, systems that operate according to a thermodynamic cycle (generally the Rankine cycle) are used. However, the profitability of these plants is still limited due to the complex and expensive systems required for their operation.
Saline gradients
La energy of salt gradients, blue energy, is obtained by taking advantage of the difference in salt concentration between sea water and fresh water in rivers. This energy is captured mainly through osmosis or reverse electrodialysis processes.
This technology is currently in an experimental phase, with pilot projects such as that of Statkraft in Norway, which opened the world's first osmosis plant in the Oslo Fjord.
How to harness this energy
Harnessing marine energy remains a challenge, but its potential is enormous. wave energy is the one that has made the most progress in terms of research and development, with pioneering projects in places such as the United Kingdom and Portugal. However, the Seawater energy, despite its more localized impact, has been used successfully in locations such as La Rance, although it has not been widely replicated due to its high environmental impact.
The Ocean currents, although promising, face the problem of maritime traffic in some areas of high interest. However, if the technology to deploy turbines in sufficiently deep areas is developed, this drawback could be reduced.
On the other hand, the use of thermal and saline gradients is still at an experimental stage and is not profitable at the moment. However, this does not mean that these technologies have no future, since investment in research and development continues.
The potential of marine energy in the future
The development of marine technologies has been slower than other renewable sources such as wind or solar energy, but their potential is evident. According to the International Energy Agency, by 2050, marine energy is expected to contribute 10% of electricity generation in Europe, which shows a promising horizon.
The development of new technologies, coupled with increased international cooperation, is driving many pilot projects around the world. Regions such as Scotland, Spain and Norway are leading the way in this area, with projects targeting wave and tidal energy.
In Latin America, countries such as Chile, Brazil and Mexico have begun to develop their own marine energy projects, showing that interest in these technologies is beginning to globalize.
With the support of government policies and adequate financing, marine energies are likely to become an integral part of the global energy mix in the coming decades. These energies are not only renewable and inexhaustible, but also have a low environmental impact and could generate thousands of jobs in the renewable energy industry.
As technological advances and costs continue to decline, marine energy will play a crucial role in the transition to a clean and sustainable energy future.