An announcement yesterday by researchers at California’s Lawrence Livermore National Laboratory that they have demonstrated “fusion ignition” for the first time has led to a wave of optimism across the scientific community the breakthrough could pave the way for limitless clean energy. The event is compared to striking a match, only on a whole different level. Fusion ignition leads to the kind of perpetual fusion reaction that happens at the centre of the sun.

Imperial College London physicist Arthur Turrell, who is not involved in the research, described the achievement by colleagues in California as:

“Some of the most fearsome scientific and engineering challenges that humanity has ever taken on. This phenomenal breakthrough brings us tantalisingly close to a demonstration of net energy gain from fusion reactions — just when the planet needs it.”

While hugely prospective there is, however, much work still to be done by the Lawrence Livermore National Lab team and wider scientific community. The $10 billion experiment that demonstrated fusion ignition only released enough energy to boil a kettle. Scaling that to the kind of power supply needed to sustain a town or city will require a “a fundamentally different kind of reactor”.

But the breakthrough has demonstrated the possibility of scientists sparking the kind of near limitless supply of nuclear energy that would revolutionise the global decarbonisation drive required if climate change is to be limited. Scientists are considering it a tipping point.

Nuclear fusion is the same process that powers the sun and, unlike the fission process used by today’s nuclear power plants, involves melding atoms together rather than splitting them. The huge advantage of that is that it doesn’t produce any radioactive waste. The tricky part is that achieving nuclear fusion means maintaining temperatures of over 100 million degrees Celsius.

Another challenge still to be overcome is the development of a reactor able to produce more energy than it needs to be fed to start the fusion reaction.

The experiment that brought the breakthrough saw a laser light generated by the National Ignition Facility focused on a 5mm-wide target capsule containing nuclear fuel. The laser’s beam catalysed a hotspot so concentrated it was about the diameter of a human hair but generated ten quadrillion watts of fusion power for 100 trillionths of a second.

The energy is released by hydrogen atoms in the fuel capsule fusing into helium, producing temperatures multiples of those found in the centre of the sun. The fuel capsule was also placed under twice the pressure of that found inside a star like our sun.

Debbie Callahan, one of the physicists working on the project explained the significance of the breakthrough with:

“It’s a huge milestone, we’ve been working on this for 50 years. We’re not going to put power on the grid anytime soon — but this is a step that we needed. This puts us in a new regime.”

Crucially, the fusion reactions the team of researchers succeeded in catalysing look like they are self-sustaining. Particles flung out from the tiny target of the laser also super-heated surrounding hydrogen atoms which also then fused. The amount of energy produced by the reaction, while small, was still a new record and around eight times that previously achieved. It was around two thirds the energy delivered by the laser which, while still an energy deficit, has given scientists hope further improvements will eventually see a surplus produced.

Clean energy production is also not the only positive outcome the nuclear fusion breakthrough is likely to lead to. Aidan Crilly of the Centre for Inertial Fusion Studies explains:

 “Reproducing the conditions at the centre of the sun will allow us to study states of matter we’ve never been able to create in the lab before, including those found in stars and supernovae.”