Meet the Wendelstein 7-X stellarator.
It looks like a mad scientist’s project, and sounds like one too: it’s the world’s largest nuclear fusion reactor, and it aims to generate energy in the same way as the atoms in the sun.
Scientists at the Max-Planck-Institute in Greifswald, Germany, have just switched it on for a first test and they are pleased with its performance.
They hope it will revive interest around nuclear fusion as an unlimited and clean source of electricity.
“A typical nuclear power plant, a fission plant, creates waste, nuclear waste that has to be stored for tens-of thousands of years. With fusion, we don’t have that problem,” said Thomas Klinger, the project’s scientific director.
Nuclear reactors typically produce energy by breaking down atoms. A fusion reactor like the stellarator instead attempts to fuse atoms together. But this requires temperatures of more than 100 million degrees, so the fuel, a thin hydrogen plasma, better not touch the walls. As a result, stellarators are extremely sophisticated — this one took nine years to build.
Still, scientists believe it’s worth the hassle.
“It’s like planting trees. If you don’t plant your trees now then you won’t have any in a hundred years. You have to think ahead,” said Klinger.
This technology takes years and years to perfect, and with their work they hope to point the way to building a commercially viable fusion power plant.
Most fusion reactors are designed as doughnut-shaped tokamaks, as in the experimental ITER plant being built in Cadarache, in southern France.
The key is to create a powerful magnetic cage to contain the hydrogen as it reaches devilishly hot temperatures. The stellarator developed in Germany has even more twists and turns to make it easier to keep this plasma under control.