Scientists claim to draw electricity from water droplets
A recent study found that ultra-thin layers of iron generate electricity when salt water flows through them. This effect can be used as a new way to generate electricity in existing infrastructure or to develop new solutions..
The phenomenon, discovered by researchers at the California Institute of Technology and Northwestern University, is not associated with chemical reactions, but is based on the conversion of the kinetic energy of flowing salt water into electricity. This effect was previously observed in graphene films and it was found that the conversion efficiency is about 30%.
Since it is difficult to produce enough two-dimensional material for industrial use, scientists have begun to explore more affordable alternatives. As a result, they found that iron oxide films are also suitable and easier to create and scale..
Although on iron alloys, rust appears by itself, but to obtain a continuous layer on a thin sheet metal, the team used physical vapor deposition. This method involves converting solid materials into steam, which condenses on the desired surface. As a result, they created a layer of iron oxide 10 nm thick, which is about 10 thousand times thinner than a human hair..
When they took a sheet of iron covered with rust and poured salt water solutions of various concentrations over it, they found that in it several tens of millivolts and several microamperes per cm2 are generated. When using a sheet of 10 m2, it will be able to generate several kilowatts of energy per hour, which is enough to provide 1-2 ordinary apartments.
The mechanism for generating electricity by the electrokinetic effect is complex and includes ionic adsorption and desorption. But, in essence, it works like this: the ions present in salt water attract electrons in the iron underneath the rust layer. Ions in the water move with it and due to the force of gravity, they pull behind them electrons in the gland, generating an electric current.
The researchers say this phenomenon can be used effectively in areas where there are moving saline solutions. Options include the use of tidal power, or passive wave energy conversion systems on buoys or other objects in the sea or ocean. They even considering using the movement of salt water in human veins to nourish implants.
We also previously reported on improvement of electrolysis technology sea water.
text: Ilya Bauer, photo: Unsplash