Germany is about to start up a monster machine that could revolutionize the way we use energy

For more than 60 years, scientists have dreamed of a clean, inexhaustible energy source in the form of nuclear fusion.

And they're still dreaming.

But thanks to the efforts of the Max Planck Institute for Plasma Physics, experts hope that might soon change.

Last year, after 1.1 million construction hours, the Institute completed the world's largest nuclear fusion machine of its kind, called a stellarator.

They call this 52-foot-diameter machine the W7-X.

And after more than a year of tests, engineers are finally ready to fire up the $1.1 billion machine for the first time. It could happen before the end of this month, Science reported.

The black horse of nuclear reactors

Known in the plasma physics community as the "black horse" of nuclear fusion reactors, stellarators are notoriously difficult to build.

The GIF below shows the different layers of W7-X, which took 19 years to complete: