Salt water flowing over thin layers of rust generates electricity

It's not unusual to find rust around salt water, but now the pairing might actually be useful. Researchers at Caltech and Northwestern University have found that electricity can be produced when salt water flows over the top of thin films of rust. The process was previously seen in – what else – graphene, but rust is far easier to scale up.

Salt water is a common ingredient in batteries, usually as an electrolyte. It shows up in simple salt-water-powered lamps, huge redox flow batteries, and even in an experimental osmotic power generation plant.

But this new system works on a different principle to all of those examples. Rather than chemical reactions, the rust generates electricity using the electrokinetic effect, or the energy of the water's movement as it flows past. Basically, it works because the ions in the salt water attract the electrons in the iron under the layer of rust. As the salt water and its ions flow, that attraction drags the iron electrons and produces an electric current...