There are different types of energy, renewable and non-renewable. Among these are wind, solar, hydraulic, thermal, electrical energy, etc … Surely you have heard the name of all of them, but there is more. In this article we will talk about a lesser known type of energy that is still halfway there. Do you know blue energy? Perhaps by blue you think that water intervenes and, indeed, blue energy or also called osmotic energy is generated when two flows of water with different levels of salt concentration come into contact.
Blue energy, what is it?
The blue energy or osmotic energy occurs when contacts seawater having higher salt concentrations in the fresh water containing a lower concentration of salts. That is why blue energy could be an inexhaustible source of energy, as well as not having a negative impact on the environment. But how is this energy produced?
How blue or osmotic energy is produced
In order to understand how this energy called blue or osmotic is produced, it is necessary to know the concept of osmosis. Osmosis is a physical process, in which two liquids with different salt concentrations are separated by a semi-permeable membrane, and through this the liquid with less salt concentration flows towards the more concentrated one.
Therefore, to obtain blue energy , seawater and fresh water must be separated by the semi-permeable membrane, which only allows water to pass through and not salts. Water flows naturally from less concentrated to more concentrated, decreasing the saline concentration and exerting a pressure called osmotic pressure . This pressure is what makes a turbine start to move in order to produce energy .
Before we have said that this type of energy is halfway, despite being an inexhaustible source of energy. What is the problem? A truly efficient system that generates large amounts of energy has not yet been found, in addition to the high costs involved at the moment.
The great benefits of blue energy are described below :
- Blue energy, like wind and solar, is renewable and will never run out.
- It is also a constant energy , that is, usable 24 hours a day, we can always obtain it regardless of weather conditions. For example, to obtain solar or wind energy, we depend on whether it is windy or the day is sunny, for blue energy we must not take the weather into account.
- With this type of energy, the entire planet could be supplied, since it occurs throughout the world, the only thing that is needed is for the river water to come into contact with the sea water.
- CO2 emissions are a real problem for climate change. The plants to obtain this type of energy do not have CO2 emissions . Their ecological impact is very low thanks to how they are designed.
After seeing the advantages, here are the main disadvantages of blue or osmotic energy :
- Earlier we mentioned that blue energy is halfway there, despite all the advantages it has, the disadvantages outweigh, for now, and this is mainly due to the high costs involved in generating it.
- Building a salinity plant already involves an economic investment, but the real problem with this is that to put it into operation, the price per megawatt is double that of fossil fuels .
- Semi-permeable membranes are really expensive but, in addition, for the pressure necessary to be able to move the turbine that will then produce electricity, they must be large semi-permeable membranes .
As time progresses, new methods are discovered to be able to make use of blue energyin an efficient way. In 2009, the first plant with the necessary technology to produce it was inaugurated in Norway, but it barely produced 10 KW of electricity. Later in the Netherlands another type of technique called reverse electrodialysis (RED) was used, which achieved a higher productivity with 50 KW, although it is not enough to replace the energy obtained by burning fossil fuels. As long as there are fossil fuels and generating energy from them is cheaper than obtaining it through renewable sources of resources, this will be the one that will continue to be used despite the great ecological impact it has. Even so, scientists continue to investigate and in 2016 they developed a new membrane capable of generating 1 MW per square meter. And it’s not all there
This new membrane is developed thanks to nanotechnology and, although there is still a long way to go to reach an efficient system capable of facing up to non-renewable energies, scientists are on the right track.