Graphene generates electricity from salt water

Graphene + salt water = electricity. It seems too good to be true but this development in the field of green energy could really be as simple as that.

Chinese scientists have successfully developed a technique which takes hydro-electricity to an entirely new level. The principles behind it are relatively simple. Droplets of the liquid are placed on the graphene, where they remain still, thus carrying an equal charge on both sides. When movement is applied to the droplets, electrons in the salt water are desorbed at one end of the graphene, and absorbed on the other. The process generates voltage.

While the output was a relatively low 30 millivolts, there was some variance. It soon became clear that the velocity at which the droplet was dragged across the graphene strip directly impacted the voltage generated. The faster the droplet moved, the higher the voltage.

Adding additional droplets also caused an increase in voltage, which perhaps isn’t surprising when you consider that hydro-electricity has traditionally required huge volumes of water in order to work efficiently. Finding a way to scale hydro-electric power down to a smaller level, which has no impact on existing eco-systems (dams, flooding large areas etc.), has never been achieved with such promising results. The scale at which the graphene and salt water technique works is also of particular interest. The small size of the graphene strips could make it easier to install in a larger variety of areas.

This development has come after years of investigation into generating electrical power using nano-structures. One major sticking point was the ability to harvest the generated electricity. Ionic fluids were used (liquids full of charged ions), however a crucial component to the harvest was a pressure gradient, which caused the fluid to flow through a tube. The process of dragging droplets of salt water over graphene strips takes away the requirement for pressure gradients.

After testing with salt water, the Chinese scientists tried a droplet of copper chloride, which also achieved positive results.

While this technique in its current state can’t complete with the electrical generating power of a dam installed with turbines, for example, it shows tremendous promise. Graphene can scale up to larger sizes, opening up the possibility of revolutionising large scale hydro-electric power. Perhaps more interesting is that it can be scaled down. Smaller generators attached to personal devices suddenly seem like a real possibility.

Could this development lead to a world where boats with graphene hulls power themselves?

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

Search and apply for the latest engineering jobs across all industries!

Published:

Back to listing