<p>Energy Secretary Jennifer Granholm announced a “major scientific breakthrough” Tuesday in the decades-long quest to harness fusion, the energy that powers the sun and stars.</p> <p>Researchers at the Lawrence Livermore National Laboratory in California for the first time produced more energy in a fusion reaction than was used to ignite it, something called net energy gain, the Energy Department said.</p> <p>The achievement will pave the way for advancements in national defense and the future of clean power, Granholm and other officials said.</p> <p>“This is a landmark achievement for the researchers and staff at the National Ignition Facility who have dedicated their careers to seeing fusion ignition become a reality, and this milestone will undoubtedly spark even more discovery,” Granholm said at a news conference in Washington. The fusion breakthrough "will go down in the history books,'' she said.</p> <p>White House science adviser Arati Prabhakar, appearing with Granholm, called the fusion ignition “a tremendous example of what perseverance really can achieve" and "an engineering marvel beyond belief.''</p>