US researchers announced a historic nuclear fusion breakthrough on Tuesday, hailing a landmark achievement in the quest for a source of unlimited, clean power and an end to reliance on fossil fuels. The Lawrence Livermore National Laboratory (LLNL) in California said an experiment it conducted this month produced more energy from fusion than the laser energy used to drive it.”The US Department of Energy described the achievement of fusion ignition as a major scientific breakthrough that will lead to advancements in national defense and the future of clean power. LLNL director Kim Budil described it as is one of the most significant scientific challenges ever tackled by humanity.Scientists have been working for decades to develop nuclear fusion — touted by its supporters as a clean, abundant and safe source of energy that could eventually allow humanity to break its dependence on the fossil fuels driving a global climate crisis.