Nuclear Fusion: Future or Far off Fantasy?
In this final instalment of our series on nuclear energy, we shift our focus from fission to fusion. There is a running joke in fusion circles that it is always another thirty years away… but is the technology at a turning point? Will Dufton takes a closer look.
An Early History of Fusion Energy
Fusion is, in many ways, humanity’s oldest energy source. The sun is the largest fusion reactor in our solar system; it created life on earth and since the dawn of man we have fuelled ourselves with plants that rely on the sun’s energy to grow.
The plasma at the sun’s core is so dense and hot that it fuses hydrogen nuclei together. Four hydrogen nuclei combine to create one helium nuclei, emitting huge amounts of energy in the process. This is the essence of fusion energy that humanity has been trying to recreate on Earth for over 100 years.
In 1920, British astrophysicist Arthur Eddington was the first to suggest that stars fuse hydrogen to make helium. In 1932, humankind accidentally created the first fusion reactions when Ernest Lawrence and others were testing early cyclotrons in California. In 1934, a group of scientists in Cambridge published the first intentional fusion experiment, discovering helium-3 and tritium - both fusion fuels - in the process.
Fusion experimentation kicked up a notch during the Manhattan Project. Building the atomic bomb led Fermi and Teller to question whether the fission explosion they created could create the conditions for a thermonuclear (fusion) reaction. This led to the “Ivy Mike” hydrogen bomb test in 1952, which produced 700x more explosive energy than the bomb dropped on Hiroshima.
Pursuit of Controlled Fusion
As with nuclear fission, the Manhattan Project provided the trigger technologies required for nuclear fusion reactors. Humanity has been trying to control fusion power ever since.
There are several general approaches to generating fusion energy, the most well-trodden pathways being magnetic confinement and inertial confinement. All approaches seek to achieve the same goal: enough heat and pressure to fuse enough nuclei together to get more energy out than you put in to create these conditions. We have still not achieved this goal repeatedly or at scale, so the “best” pathway for fusion is still unproven.
The Importance of Design for Controlled Fusion
The 1950s and 1960s saw rapid advances in magnetic confinement fusion because of the invention of the tokamak design. Tokamaks are toroidal reaction chambers that use strong magnetic fields to trap high-energy plasma. By 1968, the tokamak approach achieved record temperatures in a Russian lab and attracted global attention. Large fusion reactors like JET in Europe set milestones in the 1980s-1990s (JET produced 16 MW of fusion power in 1997), but still fell short of breakeven (creating more energy than it used). Inertial confinement fusion research began in parallel in the 1950s, with labs using lasers to compress fuel pellets instead of magnetic fields.
Dozens of different reactor designs have achieved interesting fusion results. The key ways to distinguish between different reactors are:
1) Operating Mode: continuous operation (e.g. magnetic confinement keeping plasma in a steady state for long periods of time) or “pulsed” operation (e.g. most inertial confinement techniques, firing lasers at targets for standalone reactions that are then repeated).
2) Machine Type: varying from highly complex, like stellerators, to remarkably simple, like projectile launching rail guns, this is the chamber in which the plasma is created and confined.
3) Fuel: most fusion reactors fuse Deuterium and Tritium, two isotopes of hydrogen, but some fuse a hydrogen proton with Boron-11 and others Helium-3. Deuterium is one of the most abundant resources on the planet, derived from water. Helium-3 and Tritium are extremely rare. Beyond availability, the main difference is the temperature profiles at which ignition occurs and;
4) Energy Capture Approach: the process by which the reactor captures the energy from the neutrons that fly off once the nuclei are fused. This is a very challenging part of reactor design because of the “first wall problem:” finding a material that can remain structurally sound withstanding the heat flux of the plasma and the energy of neutron bombardment.
We have shared a market map below of all the key privately funded companies working on fusion globally, split by their general approach to fusion. In the market map we have also included some interesting companies in fusion’s supply chain like Faraday Factory and Kyoto Fusioneering, who supply high-temperature superconductive tape for magnetic confinement purposes and fuel respectively.
Recent Fusion Breakthroughs
Fusion is said always to be thirty years away, but recent breakthroughs in material science, plasma modelling, and reactor experiments could indicate that we are at an inflection point.
In January 2025, China's Experimental Advanced Superconducting Tokamak (EAST) reactor set a world record for plasma confinement. It sustained a plasma for 1,066 seconds at temperatures over 100 million degrees Celsius. This was a significant improvement from its previous record of 403 seconds set in 2023 and 101 seconds in 2021.
The U.S. National Ignition Facility at the Lawrence Livermore National Laboratory, a laser-driven inertial confinement system, has shown several times it can create more energy than inputted by its laser, the important ratio known as Q>1. However these calculations fail to account for the energy required to effectively power the laser that drives the fusion.
Commonwealth Fusion Systems, arguably the world’s most advanced privately funded fusion company, demonstrated a record 20-tesla superconducting magnet in 2021 and in late 2024 used its proprietary high-temperature superconductive tape, known as Pit Viper, to create the conditions for their SPARC reactor to reach Q>1 in the near term.
And finally, in terms of commercial traction, in 2023 Helion signed the world’s first fusion power purchase agreement to supply 50 MW of fusion power to Microsoft by 2028. There have also been enormous levels of growth investment into fusion over the past couple of years, the headline story being Pacific Fusion emerging from stealth with $900m in funding.
Nuclear Fusion: Future or Fantasy?
Consistently achieving Q>1 - by getting more energy out of the fusion reaction than we put in to cause it - will be an incredible achievement and will certainly ignite a wave of fusion interest and investment. But Q>1 is just the breakeven rate. To build a commercial-scale reactor which sends electrons to the grid will require a Q ratio of perhaps 20x this level.
The obstacles ahead of us are the same they have always been: confining plasma at a high enough temperature and pressure for long enough to create energy, without destroying the vessel in which the reaction takes place. My gut feeling is that this will require more than just a novel reactor design to achieve; we probably need new breakthroughs in materials science, too.
But that is not to dissuade the fusion builders out there. We are believers that fusion is not 30 years away any more. We also trust that as we continue to push the boundaries of the possible we will discover properties, products and science that push humanity forward in many other domains. Here at Giant we are champions of fusion and, as with the fission renaissance, are willing a fusion naissance into existence.