Power from fusion has proved too hard to generate at scale. Can recent breakthroughs and massive investment change that?
On 8 August 2021, a laser-initiated experiment at the United States National Ignition Facility (NIF), based at Lawrence Livermore National Laboratory in California, made a significant breakthrough in reproducing the power source of the stars, smashing its own 2018 record for energy released from nuclear fusion reactions 23 times over. This advance saw 70% of the laser energy put in released as nuclear energy. A pulse of light, focused to tiny spots within a 10-metre diameter vacuum chamber, triggered the collapse of a capsule of fuel from roughly the size of the pupil in your eye to the diameter of a human hair. This implosion created the extreme conditions of temperature and pressure needed for atoms of hydrogen to combine into new atoms and release, kilogram for kilogram, 10m times the energy that would result from burning coal.
The result is tantalisingly close to a demonstration of “net energy gain”, the long sought-after goal of fusion scientists in which an amount greater than 100% of the energy put into a fusion experiment comes out as nuclear energy. The aim of these experiments is – for now – to show proof of principle only: that energy can be generated. The team behind the success are very close to achieving this: they have managed a more than 1,000-fold improvement in energy release between 2011 and today. Prof Jeremy Chittenden, co-director of the Centre for Inertial Fusion Studies at Imperial College London, said last month that “The pace of improvement in energy output has been rapid, suggesting we may soon reach more energy milestones, such as exceeding the energy input from the lasers used to kickstart the process.”
