Immense hurdles remain, however, in the quest for fusion power plants. While the pellet released more energy than the lasers put in, the calculation does not include the 300 or so megajoules needed to power up the lasers in the first place. The NIF lasers fire about once a day, but a power plant would need to heat targets 10 times per second. Then there is the cost of the targets. The ones used in the US experiment cost tens of thousands of dollars, but for a viable power plant, they would need to cost pence. Another issue is how to get the energy out as heat.
Still, these stepping stones are encouraging progress.
US scientists have achieved net energy gain in a nuclear fusion reaction for the second time since a historic breakthrough in December last year in the quest to find a near-limitless, safe and clean source of energy
Scientists at the California-based Lawrence Livermore National Laboratory repeated the breakthrough in an experiment in the National Ignition Facility (NIF) on 30 July that produced a higher energy yield than in December, a Lawrence Livermore spokesperson said.
The approach, which gives rise to the heat and light of the sun and other stars, has been hailed as having huge potential as a sustainable, low-carbon energy source.
In December, Lawrence Livermore first achieved a net energy gain in a fusion experiment using lasers.
The Energy Department called it “a major scientific breakthrough decades in the making that will pave the way for advancements in national defense and the future of clean power.”
Fusion energy raises the prospect of plentiful clean power: the reactions release no greenhouse gases or radioactive waste byproducts.