Enlarge / The interior or the DIII-D tokamak. (credit: General Atomics) Using nuclear fusion, the process that powers the stars, to produce electricity on Earth has famously been 30 years away for more than 70 years. But now, a breakthrough experiment done at the DIII-D National Fusion Facility in San Diego may finally push nuclear fusion power plants to be roughly 29 years away. Nuclear fusion ceiling The DIII-D facility is run by General Atomics for the Department of Energy.