New source of electricity by nanotubes?

[manet42]

To comment:

Salt water turned into a source of electricity by nanotubes

The smaller it is, the bigger the effect! This paradox has just been observed by a team from the University of Lyon and the Néel Institute (CNRS) in Grenoble. In the journal Nature on February 28, these researchers show that drilling a hole of a few tens of nanometers through an impermeable membrane can have unexpected and significant effects on the transport of chemical species within this mini-channel.
In particular, immersing this device in a salt water tank containing potassium chloride makes it possible to very effectively separate the positive charges (linked to potassium) and negative charges (linked to chlorine) on either side of the wall. An electric current can then be recovered.

"If we extrapolate this result to a membrane pierced with billions of such tubes per square centimeter, we obtain electrical powers 100 to 1 times greater than with current devices of osmotic energy", estimates Lydéric Bocquet, professor at the CNRS and at the Institut Lumière Matière in Lyon. Enough to recover energy from seawater or salt marshes.

In fact, these researchers do not directly pierce their waterproof silicon nitride membrane. They use a nanotube, which they insert inside a larger hole before "sealing" the void with a carbon seal.

"It's very difficult to do! And the result is very beautiful", estimates Loïc Auvray, director of the Matter and complex systems laboratory at the University of Paris-VII. This delicate technique was originally aimed at building a device allowing the phenomena at play in a single small channel to be studied.

PATENT FILING

"Previous experiments had shown surprising effects with several carbon nanotubes, such as rapid gas transport. But, to fully understand what is happening, we had to work on a single tube, says Lydéric Bocquet. One of our hopes is that the fluid mechanics equations we know are different from these nanoscale scales. "

The first tests with carbon tubes fail. The researchers then use boron nitride, for which the process works. And that's the surprise. "We were perplexed and it took time to verify our measurements," recalls Lydéric Bocquet, who thinks he has now understood why electric charges circulate so well.

In the presence of water, the walls of boron nitride are covered with negative electrical charges, promoting the drainage by water of positively charged potassium. The small thickness of the assembly, one micrometer, means that the concentration gradient between the two reservoirs is greater, therefore the effect more spectacular.

The team, which has filed for a patent, now plans to manufacture a wall traversed by several nanometric channels; which requires a new process. Perhaps she will then be able to light a light bulb only from a saltwater bath. For Lydéric Bocquet, "we have to find alternative avenues in terms of energy. And it is all the more stimulating to work on unexplored avenues".

David Larousserie

Source: http://www.lemonde.fr/sciences/article/ ... 50684.html ou https://www.econologie.info/share/partag ... nmB0ja.pdf

[chatelot16]

this document is not very clear ... but it seems to me to be only the energy of salt water already usable by osmosis

better known for reverse osmosis: it takes a certain pressure to make pure water with salt water ... conversely when you have fresh water and salt water, the osmosis filter does pass the fresh water into the salt water with a good difference in level: fresh water level several dozen to put below the sea water level, therefore energy to recover with the fresh water which arrives like any hydroelectric plant

everywhere in the world where a river flows into the sea there would be a way to make one more hydroelectric plant with osmosis ... except that osmosis filters are expensive, and it is not obvious from all that it is profitable especially if they are clogged too quickly by the pollution of the river

[Christophe]

Yes it already exists, we even talked about it here: https://www.econologie.com/forums/un-projet- ... t4301.html

But here, it seems much more efficient:

we obtain electrical powers 100 to 1 times greater than with current osmotic energy devices

[chatelot16]

the osmosis systems are not perfect, it would be possible to do a little better ... but 100 or 1000 times more we exceed the theoretical maximum and we can make a perpetual movement

with 1000 times more than osmosis we largely supply a desalination plant and we start again!

[Christophe]

Well everything depends 1000 times greater than what?

A priori they speak of surface energy density ...

If we extrapolate this result to a membrane pierced by billions of such tubes per square centimeter,

... in any case it's extrapolation ...

[moinsdewatt]

the osmosis systems are not perfect, it would be possible to do a little better ... but 100 or 1000 times more we exceed the theoretical maximum and we can make a perpetual movement

with 1000 times more than osmosis we largely supply a desalination plant and we start again!

No.
It just shows how poor the pre-osmosis system was.
Do not start again with surunity and this kind of jokes.

in 2009, a very small osmosis power plant in Norway was inaugurated:

Electricity in harmony with nature

Today is inaugurated in Tofte, Norway, the first power plant in the world which will produce electric current by taking advantage of the marriage between salt water and fresh water, according to the principle of osmosis. Report on the banks of the Oslofjord, and details on this new source of renewable energy and 100% clean for the environment

....... Today in Tofte, hamlet of the Oslofjord located 58 km from the Norwegian capital, Princess Mette-Marti inaugurates the first power plant in the world taking advantage of this ubiquitous phenomenon on Earth, in plants as in our bodies.
.........

Considering the technological advances in the 1990s, it was worth re-examining the question, ”says Stein Erik Skilhagen. Using current materials (cellulose acetate, synthetic polymers), the head of the Osmosis Power section at Statkraft and his colleagues have manufactured high-performance membranes of 2 or 3 W / m2. It's much better. But not yet satisfactory. “The bar of 6 W / m2 is pivotal, analyzes Gérald Pourcelly, director of the European Institute of membranes, in the journal Science & Vie. We would go from a laboratory experiment to a technology that is likely to be competitive. " Regardless, the Norwegian engineers have decided to build a demonstration station.

In Tofte, the whole fits in the volume of a large apartment, very humid. On the first floor, the two accesses of water, salt and fresh, coming from this one from a nearby lake. The membranes, thin as paper, are rolled up in 30 m2 cuts in what looks like gas cylinders, around sixty, called modules. "In total, we have 2000 m2 of membrane," says Stein Erik Skilhagen. The two types of water enter the modules distinctly, undergo the osmotic process, and increase the volume at the salt water outlet. The excess liquid thus "transferred" is then expelled in a small turbine rotating behind a window. “With it, we will produce 2 to 3 kWh of electricity. Enough to operate… a coffee machine. ”But the important thing is less in quantity than in feasibility.

“No one has yet succeeded in generating electricity in real conditions with this method. Today the pressure is great, ”says Stein Erik Skilhagen without a pun. "Ten years ago, Statkraft took risks with this project, which cost 20-25 million euros". Especially since “Tofte is one of the worst places in Norway; here, fresh water contains tiny organic particles from agriculture. But if the idea works here, it will be applicable everywhere. ” These particles have a size of the order of a micron. The technicians therefore had to install a system of primary filters to prevent them from clogging the pores of the membranes. "We still have to purge them once a day, sometimes with chlorine, but without damaging nature."

Statkraft engineers already see further. By 2015, they plan to develop a 25-megawatt (MW) "pilot station" this time, or 1000 times more than Tofte, which is little compared to a coal-fired power plant (1000 MW) . To do this, the use of 5 million m2 of membrane would be necessary. Membranes that Stein Erik Skilhagen is working to optimize: “We feel that we have all the elements in hand. But, like a puzzle, you have to find the right combination of manufacturing parameters. Especially concerning the diffusion flows ”.

Researchers are also testing new materials, like layers of carbon nanotubes impregnated in a polymer. According to Stein Erik Skilhagen, the scientific community is increasingly active in this field, especially in the United States, where the company Oasys is progressing rapidly. “We will be very much watched today. Our demonstration is likely to be a trigger event worldwide, up to Japan, where the technology is also proven. ”
...................

read in full: http://www.letemps.ch/Page/Uuid/3b9d7c1 ... _la_nature (3 pages to unroll)

[moinsdewatt]

and this other article: http://www.blog-habitat-durable.com/art ... 01742.html speaks of 4000 W / m2 of surface of such nanotubes.

........
Bore-Nitrogen nanotubes therefore make it possible to achieve an extremely efficient conversion of the energy contained in the salt gradients into directly usable electrical energy. Extrapolating these results to a larger scale, a 1 square meter membrane of Bore-Nitrogen nanotubes would have a capacity of around 4 kW and would be able to generate up to 30 MegaWatt hours per year. These performances are three orders of magnitude higher than those of the prototypes of osmotic power plants in service today. The researchers now want to study the manufacture of membranes made of Bore-Nitrogen nanotubes, and test the performance of nanotubes of different composition.

............

we have 3 orders of magnitude more than with the Norwegian system that I documented in the post above.
And on condition that we manage to concretely make this extrapolation.

[Christophe]

http://www.bulletins-electroniques.com/ ... /72397.htm

Nanotubes to make the most of osmotic energy in estuaries

Osmotic energy, you know? It designates the energy exploitable from the difference in salinity between seawater and freshwater, these two waters being separated by a semi-permeable membrane. Experience it. Contact a salt water tank and a fresh water tank using suitable semi-permeable membranes. It is then possible to generate electricity, in two different ways, from the salt gradients. The first exploits the difference in osmotic pressure between the two tanks, a difference which will allow a turbine to turn. The second consists in using only membranes allowing only the ions to pass through. We immediately understand that the theoretical capacity of this osmotic energy concentrated at the mouths of rivers is obviously gigantic. We are talking about at least 1 Térawat which would thus be available, the equivalent of 1.000 nuclear reactors. Yes but here, the performances obtained by current technologies allowing to recover this osmotic energy are still very weak, of the order of 3 Watts per square meter of membrane.



Schematic diagram of the experiment: the osmotic transport of water through a transmembrane Bore-Nitrogen nanotube is studied. Credits: Laurent Joly (ILM)

Hence the interest of the work carried out by the physicists of the Institut Lumière Matière (CNRS / Université Claude Bernard Lyon 1) in collaboration with the Néel Institute (CNRS) and the results of which are published in the issue of Nature dated February 28. Inspired by biology and research on cell channels, they succeeded in a first: measuring the osmotic flow through a single nanotube To do this, they used an experimental device composed of an electrically insulating and impermeable membrane, this membrane being pierced with a single hole through which the researchers passed a Bore-Nitrogen nanotube with an outside diameter a few tens of nanometers. So they used the tip of a tunneling microscope to achieve this feat. It then remained to immerse two electrodes in the liquid on either side of the nanotube in order to measure the electric current passing through the membrane. This is of the order of nano-amps, more than a thousand times that produced by other current methods used to try to recover this osmotic energy.

If we extrapolate the results obtained by these researchers on a larger scale, a membrane of 1 m2 of Bore-Nitrogen nanotubes would have a capacity of around 4 KW and would be capable of generating up to 30 MW hour per year. Performances three orders of magnitude higher than those obtained by prototypes of osmotic power plants currently in service. Now, the researchers will reflect on the manufacture of membranes made of these Bore-Nitrogen nanotubes and test, in parallel, the performance of nanotubes of different composition.

[chatelot16]

so it does not increase the energy produced per kg of salt to be diluted ... it just increases the production per unit of membrane surface

So this is not the revolution of the century: what limits the energy produced on a site where there is fresh water to dilute, it is the quantity of fresh water which arrives in the sea. the membrane surface for the river is not the limiting factor

the price of the membrane is more important than the surface

will these nanotubes be cheaper at equal power?

if nanotube membranes are cheaper it would be especially useful for desalination

[Caterham756]

hello can you explain to me how we can recover the electrical energy produced by this electrochemical phenomenon?
and how can the nanotube produce electrical energy I didn't quite understand?

thanks in advance scientists!