EXPERT REACTION: Reports of a nuclear fusion breakthrough

To go from break-even, where energy output is greater than total energy input, to a commercial nuclear fusion reactor could take at least 25 years. By then the whole world could be powered by safe and clean renewable energy, primarily solar and wind.

The claim by the researchers that nuclear fusion is “safe and clean” is incorrect. Laser fusion, particularly as a component of a fission-fusion hybrid reactor, can produce neutrons that can be used to produce the nuclear explosives Plutonium-239, Uranium-235 and Uranium-233. It could also produce tritium, a form of heavy hydrogen, which is used to boost the explosive power of a fission explosion, making fission bombs smaller and hence more suitable for use in missile warheads. This information is available in open research literature.

The US National Ignition Facility, which did the research, is part of the Lawrence Livermore National Laboratory, which plays a major role in US defence and weapons research.

This result is a breakthrough for realising laser fusion confinement. It is almost like a dream to be able to generate such an effect which was once deemed impossible. The breakthrough shows the efficiency of the laser and will likely hold the answer to the world’s clean energy problems. 

Using lasers to generate fusion power would be as significant as the first Moon landing.

On top of the vast benefits we would accrue from a fusion power generator, nuclear fusion could generate billions of dollars in income for Australia through technology spinoffs and start-ups along the way.

Nuclear fusion – the energy that powers the sun – has been a holy grail of physics for decades. 

There are two main routes to nuclear fusion.  The first is magnetic confinement fusion that contains extremely high temperature nuclei in a magnetic bottle.  The second is inertial confinement fusion that uses high power lasers to blast together nuclei in a miniature hydrogen bomb, as pursued at the Lawrence Livermore Laboratory.
 
Both have come close to demonstrating energy breakeven, but now it appears that Livermore may have achieved this for the first time – a truly ground-breaking achievement.
 
I’m at the national physics congress in Adelaide where the announcement has attracted lots of interest.
 
However, it’s unlikely that fusion power – which generates no greenhouse gases and minimal nuclear waste – will save us from climate change.  The energy apparently released from the Livermore experiments is only enough to boil a kettle.
 
All the heavy lifting for the energy transition will be done by renewable energy and nuclear fission (existing nuclear power) – with nuclear fusion at commercial scale unlikely to be available until later this century, well after the 2050 deadline needed to keep global warming below two degrees.  But beyond that fusion might provide limitless energy for centuries to come.

The recent experiment at Lawrence Livermore National Laboratory is an exciting milestone for the fusion community. The results prove that it is possible to gain more energy from fusion than it is used to initiate the reaction – with some caveats.  

The calculation of energy gain only considers the energy that hit the target, and not the (very large) energy consumption that goes into supporting the infrastructure. But this should not detract from the outstanding achievement of this experiment, which demonstrates that fusion is a potentially viable path forward for a new reliable clean energy source. It tells us that we should continue to invest in fusion development to improve the efficiency of the devices.

There are now three main obstacles left to turn fusion into an engineering reality: firstly, this experiment was a short pulse, and we would need to turn it into longer pulses and eventually an even continuous process.

Secondly, it is not sufficient to have an energy gain, but it has to be sufficiently large to compensate for the energy losses of the surrounding infrastructure, and some excess which can then be converted into electricity.

Thirdly, we need to continue to develop materials capable of withstanding the harsh fusion environment for prolonged periods of time. Fortunately, there are now many national laboratories, companies and universities (including in Australia) advancing fusion energy, with a remarkable rate of progress.

The US experimenters apparently have got out more energy than they put in in a fusion experiment, thus technically achieving ignition. This indeed is a breakthrough worthy of celebration. However, there is a long way to go. From the nature of the facility where the experiment was performed, I’d say this energy came in a single pulse or “flash”. So, for a viable power source it would be necessary to have sustained repeated such pulses, and be able to collect the energy released efficiently. There’s still a long way to go. That said, achieving ignition is an essential milestone that apparently now has been reached. Practical fusion power is a step closer to reality.

 
A bit more technical detail. This is probably deuterium plus tritium fusion – the joining of the two heavy isotopes of hydrogen that is the favoured nuclear reaction to achieve fusion power. The two positively charged nuclei have to be pushed together against their electrical repulsion, which in this case is achieved by heating the isotopes in a plasma to temperatures where the nuclei are going so fast that they can overcome the repulsion and bang together."