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As reported by phys.org web page, a team of researchers from Switzerland and the USA built a micro device generating electricity based on the osmosis phenomenon. The device is composed of a three-atoms-thick molybdenum membrane (molybdenum disulfide) and two water containers. One of the vessels contains fresh water, while the other is filled with the sea water.
The membrane has got three tiny apertures (nanopores) which enable the ions coming from the sea water to pass through into the vessel filled with fresh water until the salt concentration in both containers becomes equal. The properties of this membrane make the positively-charged ions allowed to pass through its layers while the negatively-charged ones become pushed away, which contributes to the generation of electrical voltage between both liquids. There are electrodes placed inside each container, thanks to which the transfer of a positively-charged ion through the membrane forces the generation of the electricity within the circuit. The operational principle of this device may be watched on the YouTube channel of Ecole Polytechnique Federale de Lausanne (EPFL).
Generating electricity with the use of the phenomenon of osmosis is called "blue energy". For some time, there have been intensive research efforts related to the development and verification of solutions devised within the field (instead of the ion movement, there may be a method relying on the movement of water implemented). Gradually, there are test installations being created, as placed at river estuaries where fresh water flows into the sea, in order to regain energy from nature. This may be exemplified by the installations present in Norway (the project was unsuccessful) and the Netherlands.
The added value of the work of Swiss researchers is having reached extremely high efficiency of the process through the optimisation of the size of nanopores. Their calculations indicate that a square meter of such a membrane should allow for the production of 1MW power of electricity if 30% of its surface is covered by nanopores.
It is assumed that power plants generating blue electricity may become a considerable part of world's electricity production in the near future.Source: www.phys.orgOriginal paper: J. Feng i in., Single-layer MoS2 nanopores as nanopower generators, Nature, 2016.DOI: 10.1038/nature18593Image credits: PublicDomainPicturesImage source: www.pixabay.com