In terms of specifics, the lasers of the National Ignition Facility deposited 2.05 megajoules into their target in that experiment. Measurements of the energy released afterward indicate that the resulting fusion reactions set loose 3.15 megajoules, a factor of roughly 1.5. That's the highest output-to-input ratio yet achieved in a fusion experiment. //

Before we get to visions of fusion power plants dotting the landscape, however, there's the uncomfortable fact that producing the 2 megajoules of laser power that started the fusion reaction took about 300 megajoules of grid power, so the overall process is nowhere near the break-even point. So, while this was a real sign of progress in getting this form of fusion to work, we're still left with major questions about whether laser-driven fusion can be optimized enough to be useful. At least one DOE employee suggested that separating it from its nuclear-testing-focused roots may be needed to do so. //

Which gets into all the other problems that laser-driven fusion faces. Kim Budil, director of Lawrence Livermore National Lab, mentioned the other barriers. "This is one igniting capsule one time," Budil said. "To realize commercial fusion energy, you have to do many things; you have to be able to produce many, many fusion ignition events per minute. And you have to have a robust system of drivers to enable that." Drivers like consistent manufacturing of the targets, hardware that can survive repeated neutron exposures, and so on.

So, while laser-driven fusion may have reached major energy milestones, there's a huge list of unsolved problems that stand between it and commercialization. By contrast, magnetic confinement in tokamaks, an alternative approach, is thought to mostly face issues of scale and magnetic field strength and to be much closer to commercialization, accordingly.