by Lars Jaeger| December 19th, 2022
This month, the world was treated to news of a breathtaking scientific and engineering achievement. Scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in Northern California had apparently demonstrated, for the first time in history, the possibility of generating more energy from fusion than was used to initiate the process. That outcome has been the ‘holy grail’ of applied fusion physics for nearly a century because fusion would open the door to produce an energy source vastly greater than human needs and without harmful by-products from its production.
In what follows, I outline the significance of this breakthrough, as well as its limitations. Here is the punchline: As important as the Livermore outcome is, the viable development of commercial fusion technology probably resides elsewhere. But that is not a note of despair. If anything, the message is that commercial fusion applications may not be very far off.
How significant was ‘Livermore’?
According to credible reports, the scientists at the Livermore laboratory had, for the first time, succeeded in generating more energy with an experimental fusion reactor than what was used during the process. A “net energy gain” of 120 per cent was achieved. If so, that is revolutionary. After all, there have been numerous experimental reactors built for that purpose over the past 70 years, but nowhere has it been possible to generate more energy than what must be put into the reactors to produce nuclear fusion.
Physicists have known since the late 1930s that hydrogen nuclei fuse into helium atomic nuclei under very high pressure and temperature. The amount of energy released in this process is much greater than in the nuclear fission, in which heavy atomic nuclei are split.
The basic concept of nuclear fusion has been known for decades, namely that a deuterium-tritium plasma must be heated to several million degrees and must be confined with the help of a very strong magnetic field. At a temperature of about 100 million degrees, the mixture ignites and releases the fusion energy. The actual ignition temperature depends on the particle density, i.e., the pressure of the plasma. It is also possible to perform further nuclear fusion with other nuclei, such as protons with boron, but these require much higher temperatures and hence energy input.
The scientists in California utilized a different technique. Rather than using a huge magnetic field to hold the plasma, they deployed a high-power laser to bring the deuterium and tritium close enough to each other that they fused. With that technology, however, the reaction only takes place for a (very brief) instant.
The outcome, as noted, was revolutionary. But its applications may be limited. It is even questionable whether the method used is scalable given the high energy required for the laser pulses. Indeed, most nuclear physicists doubt the laser method is a viable path to commercial fusion reactors due to the short duration of the process.
It may be helpful to have a more detailed look at the NIF process. The approach is called “inertial confinement fusion” (ICF), where high temperatures are generated in very small spaces by bombarding a tiny sphere with the two hydrogen isotopes (fuel) at its center with 192 high-power lasers. Within 10 billionths of a second(!), the fuel is reduced to a minimal fraction of its original volume, bringing its core to a temperature of 50 million degrees Celsius, sufficient for nuclear fusion (given the energy “temperature” of the nuclei). However, the lasers themselves consume enormous amounts of energy and can so far only be ignited once or twice a day. That energy, which represents a multiple of the amounts of energy gained, has not even been considered in the net gain.
The technology used by the NIF is only one of many possible methods to produce nuclear fusion, some of which have substantial private sector backing. For instance, Boston-based Commonwealth Fusion Systems (CFS), a spin-off of MIT, has received more than a billion dollars from investors such as Bill Gates and George Soros. Their approach to fusion is more traditional, in which strong magnetic fields control spheres in a plasma of hydrogen about 100 million degrees. The aim is to produce the same fusion of hydrogen isotope nuclei as in the laser-driven reactor.
Yet more than one winner may emerge. Canada-based General Fusion, backed by Jeff Bezos, received $130 million from investors last year. As with magnetic confinement in CFS, their approach holds the fusion fuel together with magnetic fields as it is heated to form a plasma, which is then rapidly compressed.
Finally, TAE Energy in California appears furthest along in the development of commercially successful nuclear fusion. It has spent over a billion dollars in the past two decades and aims to build the first permanently functional nuclear fusion reactor within the next two to three years under the name of “Copernicus”. It will also operate with hydrogen isotopes and aims to achieve a (permanent) net energy gain by 2025.
TAE’s reactor combines a particle accelerator and a plasma vessel. The ultra-high temperature in the plasma is achieved by accelerating beams of fuel particles and then colliding them with plasma particles. Theoretically, their approach can be used to reach much higher temperatures than 100 million degrees. TAE has found evidence that the stability and quiescence in the plasma increases with higher temperature. That is important for scaling and very high temperature fusion.
Follow the science, but also the money
The Livermore news is indeed exciting. But the fusion breakthroughs that could transform our lives are more likely to be found in commercial rather than purely scientific laboratories that are devoted to harnessing the energy of the atom.
The fact that investors are willing to put up billions of dollars of private capital into the development of nuclear fusion energy applications is a good indicator that the technology is feasible, perhaps even in years rather than decades. Increasingly, fusion appears viable in our lifetimes.
Commercially available fusion technology would usher in a societal paradigm shift. It would deliver to mankind the power of the sun, safely on earth. It would open the door to the most efficient, safest, and environmentally friendly form of energy that nature has to offer. This would not be a mere technological advance, but rather an enormous leap forward for civilization on a par with the harnessing of fire, the invention of the steam engine, and the ability to store and transmit electricity.