In a big, scaffolding-riddled room at the Max Planck Institute for Plasma Physics of Greifswald, north east Germany, a bunch of physicists and engineers are getting very excitable.
They're about to turn on a 16-metre-wide machine that has the potential to end the energy crisis.
It's name? The Wendelstein 7-X, a stellarator fusion reactor. This is why it's important.