US to reveal nuclear fusion breakthrough in quest for clean energy
- Scientists at Lawrence Livermore National Laboratory have achieved a net energy gain for the first time, in an experiment using lasers, insiders say
- Being able to generate more power than the amount going into the reaction is a milestone in the process, but commercial viability is still some time away

The US Department of Energy on Tuesday will announce that scientists at a national lab have made a breakthrough on fusion, the process that powers the sun and stars that one day could provide a cheap source of electricity, three sources with knowledge of the matter said.
The scientists at Lawrence Livermore National Laboratory in California have achieved a net energy gain for the first time, in a fusion experiment using lasers, one of the people said.
While the results are a milestone in a scientific quest that has been developing since at least the 1930s, the ratio of energy going into the reaction at Livermore to getting energy out of it needs to be about 100 times bigger to create a process producing commercial amounts of electricity, one of the sources said.
The Financial Times first reported the experiment.
Fusion works when nuclei of two atoms are subjected to extreme heat of 100 million degrees Celsius (180 million Fahrenheit) or higher leading them to fuse into a new larger atom, giving off enormous amounts of energy.
But the process consumes vast amounts of energy and the trick has been to make the process self-sustaining and get more energy out than goes in and to do so continuously instead of for brief moments.