Can we produce electricity from salt waters (for example saline ground waters or salty rivers), efficiently? Could you plz give some references or elaborate on that.
Thank you
Experiments in France have already been carried out in this direction. I think in 2013.
A little water, a pinch of salt and a few nanotubes. Here's a simple list of ingredients. However, these three elements are sufficient to produce electricity!
The results obtained by scientists from the University of Lyon (France) and the Néel Institute of Grenoble (France) pave the way for an alternative energy source method. Results that are already patented. But how does it work?
The system is based on nanotubes introduced into an impermeable membrane.
More specifically, the nanotube is inserted inside a hole of a few tens of nanometers made in the silicon nitride membrane. Then, the space between the wall of the nanotubes and the membrane is filled with a carbon seal.
Once immersed in saltwater, this device makes it possible to recover an electric current: the positive charges linked to potassium are separated from the negative charges linked to chlorine, each group of charges being positioned on either side of the wall.
The small thickness of the assembly, less than a micrometer, imposes a very large concentration gradient. Hence a more efficient displacement of loads than on the macroscopic scale. So much more effective that the researchers are first perplexed by their measurements, before realizing the importance of their discovery.
But such a device is very difficult to achieve. The researchers' main objective was to use carbon nanotubes. But faced with successive failures, they decided to use boron nitride tubes. This time the result is convincing and the process works. This device is extremely promising. If we extrapolate this result to a membrane pierced by billions of such tubes per square centimeter, we obtain electrical powers 100 to 1,000 times greater than with current osmotic energy devices.
The next stage consists in manufacturing a system pierced with several channels and not only one, in the hope of creating load displacements all the more important, and why not eventually produce energy from seawater and salt marsh.
Another technique exists and has been tried out in Norway.
Osmotic energy uses the salt concentration of seawater to generate electricity. The key element of this technology is a semi-permeable double-sided membrane, which has the distinction of allowing water to pass through, but not mineral salts. It is contacted with fresh water on one side, and seawater on the other side. In this situation, the salt molecules attract freshwater, which then migrates to the salt compartment: this phenomenon is called osmosis. Thanks to this movement of water, a turbine produces electricity.
The success of this technology, therefore, rests on high-performance membranes, which must have good resistance to wear and attract enough water to drive the turbine and produce electricity with optimal efficiency. They must of course also have an acceptable cost.
An osmotic power plant cannot be installed anywhere along a coast. It indeed needs to be close to freshwater and seawater reservoirs. Therefore, the mouths of rivers represent the only suitable sites. In practice, in an osmotic power plant, a network of pipes leads fresh and seawater into separate chambers, separated by the membrane.
After several experimental installations, Statkraft, a Norwegian electricity company specializing in renewable energies, inaugurated its first osmotic installation in Tofte, Norway, in 2009. It is a prototype that is used to test the behavior of membranes in the time and the feasibility of the technology. Two other projects are being launched in Japan, with a pilot plant in Fukuoka, and in the United States.
Currently, 1 m² of membrane achieves a power of 3 W. Statkraft works with a theoretical osmotic pressure of 12 bars, the equivalent of a drop of 120 meters. Adjustments are still necessary to improve the yield and reach the 5 W / m² target. At that time, a 1 MW osmotic power plant should require 200,000 m² of the membrane. A power plant of this power (1 to 2 MW) should be built in Sunndalsøra.
It will take thousands of square meters of the osmotic membrane to use salt water as an energy source.
Regards.
Greetings and thank you Dr. Achour for the great information and through explanations.
Best wishes and regards
Today, most of the electricity we consume is generated at far from the most environmentally friendly power plants. And, despite the success in the use of solar energy, the commissioning of new technologies in the field of electricity production remains a labor-intensive and resource-intensive process. But soon everything may change thanks to a new method — getting electricity from salt water.
The technology is based on the use of a familiar osmosis process for everyone from school. The essence is simple: the power plant has two tanks — one with salt water, the other with clean water. In a container with clean water, there is a turbine that is driven by the movement of water. The containers are connected by a tube with a semipermeable membrane. Then physics comes into play: thanks to osmosis, the concentration of salts in two vessels should be the same. This causes salt molecules to rush from a container of salt water through the membrane to a container of clean water. Water vibrations drive a turbine that generates electricity. There is only one problem: this process of generating electricity has been known for a long time and the amount of energy produced is extremely small. But a group of researchers from Switzerland and the United States has found a way to increase the output energy several times.
In the invention of scientists, the main component that allows to achieve an increase in energy output is a new type of membrane. Salt water and pure water are located in the same vessel, separated by an ultra-thin semi-permeable membrane. The membrane passes only positively charged ions. Electrodes are connected to the membrane. When a positively charged ion passes through the membrane, it gives its electron to the membrane, which transfers the charge to the electrodes, which leads to the production of electricity.
The advantage of the technology is that there can be a lot of such "gates" for ions in one membrane and, as the developers themselves say, a membrane with an area of 1 square meter can generate up to 1000 kilowatts of energy, which is enough to provide electricity to about 600 apartments.
Greetings and thank you Dr. Ataev for the very interesting and exciting answer. I hope this technology becomes a reality and cost effective.
Best wishes and regards
I believe Bruce Logan's lab at Penn State is looking into this. Here is one such publication: https://pubs.rsc.org/en/content/articlelanding/2014/ee/c3ee43823f/unauth#!divAbstract
Hello Dear Dr. Farhad Khorsandi
I hope the following links could be useful!
https://medium.com/@tjsmedley/blue-energy-can-we-get-all-our-future-energy-from-salt-water-d1e4f910d763
https://www.sciencedaily.com/releases/2019/07/190729151859.htm
https://economictimes.indiatimes.com/news/science/new-method-can-generate-electricity-from-seawater/articleshow/52386326.cms?from=mdr
Best Regards
Greetings Dr. Hazbavi
Thank you so much for all the very useful links.
Best regards
Please review the following link hope contain excellent information:
Article Salt in freshwaters: Causes, effects and prospects - Introdu...
Dr. Virendra Kumar Saxena
Since there are different technologies for generating electricity from salt waters, do you have evidences for your statement? Or you just speculate that it is not economically viable? Do you agree that many of the renewable energy technologies in use now, were not economically viable at first? But the engineers continued ...... Besides, sometimes social demands and needs, makes use of a technology justifiable.
Thank you.
On line line literature and sufficient literatures are available. In India, we have salt water problems which is contaminating the fresh water resources. Thus will be useful in our country also. Please suggest some economical processess.
Hope this link could be useful.
https://pubs.rsc.org/en/content/articlelanding/2014/ra/c4ra05968a#!divAbstract
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