If we talk about renewable energy sources, we're used to thinking of the microscopic dimensions of elements, such as sun, wind, or sea.
There is however a different way to think of renewable sources, at a, so to speak, microscopic level.
One example is the project developed by the University of Wisconsin to generate electricity from foot traffic on floors, following the same physics principle that makes clothes give us small shocks.
The main material is wood pulp, an industrial by-product, which is widely available at a very low cost. Currently, the project is testing this technology to make it as efficient and as durable as possible for surfaces with intense foot traffic.
Iceland's grid runs 100% off renewable energy already, thanks to two abundant sources: hydropower and geothermal energy.
There's no resting on laurels though, because the island is ready to use another untapped resource: volcanic activity.
The idea is to gain access to the water heated by the volcanic lava flowing in the underground mid-Atlantic Ridge.
It's the same principle of geothermal power, but with much higher water temperatures and pressure, and a potential of 50 mW. That's ten times as much as a geothermic well.
You're probably familiar with businessman Elon Mask's project to take humans to Mars, with his aerospace company SpaceX. Here we want to show you a picture of one of the tanks of the spaceship, published on their Instagram.
It's entirely made of "advanced carbon fibre" and it will contain liquid oxygen and methane, which will also be generated from carbon dioxide and water taken from Mars atmosphere.
To get an idea of its size, just compare it with the two men standing at its feet.