A team of Chinese scientists did an impossible-sounding thing. They created electricity simply by dragging a droplet of saltwater across a layer of graphene. No big fires, no greenhouse gases, no fuss. They created energy with just a miracle material and one of the most plentiful substances on Earth.
The science behind the effect is actually quite simple. When the droplets of saltwater sat static on the graphene, they carried an equal charge on both sides. But, when moved across the surface of the graphene, the electrons in the saltwater were desorbed on one end of the graphene and absorbed on the other, generating a measurable voltage along the way. The faster the water moves, the higher the voltage it generates — although the total voltage was still pretty low, about 30 millivolts. A standard AA battery, by comparison, produces about 1.5 volts. It helps that graphene is insanely conductive.
So that's not much — not yet — but it's something. It's not the voltage that scientists are excited about, though. It's the scale. Current hydroelectric power solutions can only exist on a very large scale. Think Hoover Dam. However, this method for producing hydroelectric power could support nano-sized generators without any byproducts. They do believe the method will scale up too. That is, if anybody can afford that much graphene. [Nature via Ars Technica]