German scientists are about to turn on a nuclear fusion machine that has the potential to unlock a new clean, safe, and abundant power source. Engineers at the Max Planck Institute for Plasma Physics spent 1.1 million working hours building the machine, called the Wendelstein 7-X (W7-X). Measuring more than 50 feet wide, it is the largest stellarator in the world, and it’s about to be fired up for the first time.
Although nuclear fusion is considered to be one of the most promising options for generating large amounts of carbon-free energy, scientists have spent 60 years trying to make it work. Past attempts have ended up consuming more energy than they produce.
Nuclear reactors work by replicating the process that heat the Sun, where atomic nuclei collide together and release energy. To do this on Earth, reactors must generate, confine, and control plasma. The machines heat and contain gas at more than 100 million degrees Celsius, which is seven times hotter than the sun’s core. At this temperature, electrons separate from their atoms to form ions, but the extreme conditions make the ions travel so fast that they overcome their normal repulsion, and voila: fusion occurs.
The W7-X is a type of nuclear reactor called a stellarator. It is considered a cousin to the more popular devices, tokamaks, which are better at keeping gas trapped and holding on to the heat needed for continuous reactions. Stellarators are notoriously difficult to build, but they have major potential because they overcome a fatal flaw of tokamaks, which produce troublesome magnetic disruptions. Science reports that the W7-X is “the first large-scale example of a new breed of supercomputer-designed stellarators that have had most of their containment problems computed out.” After a year of testing, this exciting new prospect for a commercial fusion power plant is expected to be turned on by the end of this year.