Mexico Explores Marine Renewable Energy
Mexico has immense potential for renewable marine energy. Waves, currents, and temperature/salinity gradients can be harnessed for electricity. Researcher is leading efforts to study and develop this resource, focusing on Mexico's powerful Yucatan Current.
Available to be studied and exploited, renewable marine energies are a resource that we must consider in Mexico, a country that, according to data from the Ministry of Environment and Natural Resources, 17 of its 32 federal entities border on maritime zones.
To investigate the possibilities of energy extraction, Cecilia Enríquez Ortiz, professor of Oceanography and Coastal Processes at the National School of Higher Studies, Mérida Unit, of the UNAM, has participated in government and academic initiatives to make the possibility of obtaining them from the seas a reality.
“Almost a decade ago, the Mexican government began to promote research into renewable energies of various types. When the Center for Research in Renewable Ocean Energies was created, we formed a very large group of academics from all over the country to address the different sources of energy that exist in the seas,” she recalled.
She explained that they exist in the waves and in the marine currents, as we can see and feel when we go to the coasts. But there are other sources that are not as visible, such as temperature gradients, which have a large amount that, with the appropriate technology, can be used to convert it into electricity, and also salinity gradients, she explained.
The wave energy is predictable, since it flows towards the coasts where it can be captured and transformed, through converters, into useful energy. The marine current energy (important in the areas of the Gulf of California, the coasts of Quintana Roo and the Cozumel current, and the Caribbean Sea) takes advantage of the speed of the water flow, through a turbine that generates electricity.
The specialist explained that, to exploit any resource on the planet, it must first be studied precisely to know how much there is and how it varies.
“We know that the Sun rises every day and that throughout the day we can have, with the appropriate technology, solar energy. But every time a cloud passes, the panel stops generating; there are weeks or months in which there is less energy. Accounting for these variations is essential for renewables,” she said.
The gradient of something is a difference that exists from one limit to the other in a range of variation. We say that there is a color gradient when we go from one extreme to the other through different colors, he explained.
The temperature or thermal gradient consists of pumping water from the bottom of the sea (which is 500 to 1,000 meters deep, with a temperature of four to seven degrees Celsius) to the surface.
Surface water registers 24 to 28 degrees Celsius and through heat exchangers it is transformed from liquid to gas. In the second state, energy is produced through a turbine connected to a generator.
In the case of the salinity gradient, a membrane is used to put fresh and saline water in contact. From the ionic exchange between the two, electricity is produced.
“In mathematical terms, the gradient is the change of something throughout a space. In the case of the salinity gradient, if I have fresh water colliding in a very small space, the gradient is very large.”
For example, at the mouths of rivers in the oceans, fresh water collides with salt water. All the energy from this collision is released spontaneously in the form of heat and could be used, she said.
The specialist stressed that each technique requires specialized technologies and field work. In the case of Mexico, the most useful is that of marine currents, since our country is fortunate to have one of the most attractive for the extraction of the resource: the Yucatan current. It is one of the most intense in the world, with a stable direction that flows north before entering the Gulf of Mexico.
