(CNN) Professor Thomas Klinger heads up one of the world's most advanced nuclear fusion projects at the Max Planck Institute in Greifswald, Germany, where 400 scientists from around the world have invested over one million manpower hours to build the Wendelstein 7-X, a prototype nuclear fusion reactor.

It's called nuclear fusion: a method to produce energy which promises to be limitless, clean and accessible to all.

Nuclear fusion is the same process that powers the sun, and it's what scientists are trying to imitate to create a power source on earth that could one day replace fossil fuels entirely, offering limitless and clean energy.

For the moment, this is just a test, since it consumes far more energy than it creates. But it will provide valuable data if we are ever to build a nuclear fusion power plant.

This is a different process from the one used in traditional nuclear plants, which use fission. The risks associated with these plants have resulted in accidents such as Chernobyl in 1986 and the Fukushima disaster in 2011. Nuclear fusion, which Klinger and his colleagues are working on, promises to be safe, and generates no radioactive waste or other byproducts.

The Wendelstein 7-X experimental fusion reactor.

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