In the vast majority of futuristic societies portrayed in science fiction books and movies, humanity has access to what is basically unlimited energy thanks to nuclear fusion. It powers planet-spanning cities, interstellar spaceships and technology that bends the laws of physics.
After all, fusion, which takes place in the center of stars, produces most of the energy in the universe. It would be a clean and sustainable power source for humanity, not to mention efficient, with fusion creating nearly four million times more energy per kilogram of fuel than fossil fuels.
However, despite nearly a century of research and numerous scientists, companies and governments perpetually right on the cusp of a breakthrough, a fusion reactor that produces more energy than is put into it has yet to come to fruition. So just how far have we come and how much farther does humanity have to go to crack nuclear fusion?
THE POWER OF STARS
To discover the process of nuclear fusion, scientists built on the ideas developed by Albert Einstein in his Theory of Special Relativity. Published in 1905 with the famous equation E = mc2, it described the relationship between mass and energy.
Soon thereafter in 1920, in his book Internal Constitution of the Stars, British astrophysicist Arthur Eddington postulated that this relationship was responsible for the massive amounts of light, heat and other energy produced by the sun. Specifically, he theorized that inside the sun, hydrogen atoms were fusing together into helium atoms, and in the process converting a portion of their mass to energy.
From there, many scientists built on this idea to determine exactly how the nuclear fusion process inside the sun was taking place. Most notably, Ernest Rutherford discovered the internal structure of the atom, for which the “Rutherford” model, which you probably remember from high school, was named.
From there, he went on to conduct an experiment in 1934 in which he and his protege Mark Olphant used particle accelerators designed by Oliphant to actually fuse atoms of deuterium, a “heavy” hydrogen isotope that has one proton and one neutron in the nucleus. This was the first instance of nuclear fusion being initiated in a laboratory.
Of course, this research was occurring at roughly the same time as research into nuclear fission, which splits large atoms like uranium instead of combining small atoms like hydrogen. Just as world governments before and during World War II saw the potential of fission for use in military weapons, ultimately culiminating in the atomic bomb, they saw the same potential for fusion.
In fact, the idea for a thermonuclear fusion bomb was developed alongside that of the fission-only atomic bomb by Enrico Fermi and Edward Teller. Work continued after World War II, motivated by the Soviet Union’s successful atomic bomb test in 1949. By May 1951, Operation Greenhouse tried out the first small-scale fusion bomb in a test nicknamed “George.” It was successful with a yield of 225 kilotonnes of TNT, more than 17 times the yield of the Little Boy atomic bomb dropped on Hiroshima.
Nevertheless, George was indeed “small scale.” To date, the world’s largest detonated fusion bomb, the Tsar Bomba developed by the Soviet Union and tested on 30 October 1961, yielded an unreal 50 megatonnes (that’s the equivalent of 50 million tonnes of TNT), showing just how much power can be harnessed from nuclear fusion.
THANKS TO A PRANK
On 24 March 1951, Argentine president Juan Perón held a press conference where he proclaimed to the world that his scientist Ronald Richter had accomplished the “liberation of atomic energy,” not through the fission of uranium but through the “controlled thermonuclear fusion” of hydrogen.
Apparently, President Perón and the Argentine government had poured the equivalent of almost 300 million US Dollars into Richter and his top-secret Proyecto Huemul, located on a remote lake island of the same name. There Richter built a 40-foot-tall concrete bunker to shelter his reactor, which he claimed began producing positive amounts of energy by February of 1951.
At the time, Argentina was still a mostly rural nation of just 16 million people, and it shocked the world that the country could accomplish nuclear fusion before the industrial, economic and military powerhouses of the United States and Soviet Union. After all, it would still be a couple of months before the US would successfully test a fusion weapon. Indeed, the international scientific community quickly noticed some problems with the data and certain unverifiable aspects of the experiments.
Ultimately, Richter’s purported fusion reactor was revealed to be a prank, scam or just the claims of a madman. Whatever it was, there was no successful fusion reactor and President Perón actually threw Richter in prison for embarrassing him on the world stage.
Still, the incident is in large part responsible for the interest and direction of nuclear fusion research to this day. Not only did it light a fire under scientists in larger countries, but some of Richter’s ideas, like ion acoustic plasma heating, inspired later reactor designs and experiments.
In fact, astrophysicist Lyman Spitzer, who was working on the US’ fusion bomb at the time, was so impressed by the news that he spent several days skiing and pondering the ramifications of Richter’s supposed reactor design, specifically the idea of confining hot plasma within a magnetic field. He went on to develop the figure-eight stellarator based on the idea, a reactor design so promising that the US government shifted its Project Matterhorn from weapons research to reactor power research. Project Matterhorn, which was eventually renamed the Princeton Plasma Physics Laboratory, ushered in the modern age of fusion research and technology.
Beginning with Spitzer’s design, research primarily focused on magnetic confinement, which uses powerful magnetic fields to keep superheated plasma in a confined enough space to facilitate its fusion into heavier elements, thereby releasing energy.
For a fusion reactor to start, it must overcome one primary obstacle: the Coulomb force, also known as the electrostatic force, causes atoms to repel each other at large distances. However, if the atoms are brought close enough together by some other means, the strong nuclear force can overcome this and cause the atoms’ nuclei to fuse together into a single atom. In stars like the sun, this is achieved via large amounts of gravity, but on Earth, scientists must find some other way to compress the atoms together, such as magnetic confinement.
Through most of the 50s, fusion research was done in secret under classified government programs, focusing mostly on Spitzer’s magnetic confinement method. However, in 1958, the major powers like the US, UK and Soviet Union agreed to declassify and share their research at the Second Geneva Conference on the Peaceful Uses of Atomic Energy. As a result, research into fusion reactors became mostly a cooperative international endeavor, which accelerated innovation.
For example, a method called “inertial confinement fusion” came on the scene as another popular approach starting in the early 60s. In inertial confinement fusion, the nuclear fuel, usually a mixture of deuterium and tritium, an even heavier isotope of hydrogen with one proton and two neutrons in the nucleus, is basically shot with lasers until the outer layer overheats and explodes, compressing the inner layer and initiating fusion.
Similarly, Spitzer’s original stellarator concept for magnetic confinement was largely replaced by the tokamak design developed by I.E. Tamm and A.D. Sakharov in the Soviet Union. To the untrained eye, both stellarators and tokamaks look basically the same: like giant donuts, technically called tori, the plural for torus. However, they differ significantly in how they generate magnetic fields to maintain the plasma.
Specifically, a tokamak maintains a relatively consistent magnetic field in the shape of a helix traveling around the donut by combining the magnetic field of external coils around the exterior of the donut and a magnetic field created by the plasma itself. This causes the plasma to move in a current around the donut. Meanwhile, a stellarator uses coils on the outside of the donut that are not symmetrical with the donut’s axis. This creates a twisting magnetic field.
Both designs have their advantages and disadvantages. In essence, tokamaks are better at keeping the plasma hot while stellarators are better at keeping it stable since there is no plasma current. Still, tokamaks are the preferred method today with 60 in operation versus only 10 stellarators, though interest in stellarators has begun to see some resurgence in recent years.
It’s not all donuts, though. There’s another magnetic confinement design called “mirror confinement,” in which the plasma is held in what’s basically a straight tube with magnetic “mirrors” on either end. These are just extra strong magnetic fields that “reflect” any particles trying to escape back into the middle.
Still, for magnetic confinement methods as well as inertial confinement, all the reactors developed so far have hit the same brick wall. To achieve fusion, the plasma has to be heated to around 100 million degrees Kelvin, which is roughly the same in Celcius or some 180 million degrees Fahrenheit. Plus, this insanely hot plasma must then be kept stable by whatever confinement method is used.
Obviously, this takes a lot of energy. To measure the ratio of energy output to input in a fusion reactor, scientists use what’s called the “fusion energy gain factor,” abbreviated with the symbol Q. A Q factor of 1 would mean the reactor puts out the same amount of energy that goes into heating it and keeping it stable, while a number higher than 1 would mean it’s producing excess energy.
The record for Q was set in August 2021 by the National Ignition Facility at the Lawrence Livermore National Laboratory in California using the inertial confinement method. Requiring 1.9 megawatts of energy to produce 1.35 megawatts, it had a Q of roughly 0.7. In other words, the most efficient fusion reactor to date only produces 70% the amount of energy required to run it.
WHO WILL BE FIRST?
Initiating nuclear fusion is no longer much of a challenge in and of itself. In fact, in 2020, Jackson Oswalt, a 12-year-old in Tennessee, set the record for the youngest person to achieve nuclear fusion using parts he got online assembled in his family’s playroom.
Since the 50s, numerous governments, laboratories, international organizations and private companies have tried their hand at finally breaking Q1. Even though none have reached it yet, they continue to set impressive records, coming ever closer to the elusive breakeven point. Based on theoretical models, many claim they can achieve efficient nuclear power in the near future. But who will be first?
JOINT EUROPEAN TORUS (JET)
With construction having begun in 1978 and first plasma initiated in 1983, the Joint European Torus, or JET, is one of the oldest experimental reactors still in operation. In fact, it holds the record for fusion power produced, hitting 16.1 megawatts in 1997, enough to power about 16,000 US homes. With an electrical input of 24 megawatts, this gives JET a Q factor of 0.67.
JET is the world’s most powerful tokamak, operated by the Culham Centre for Fusion Energy and the UK Atomic Energy Authority in Oxfordshire, UK. It’s currently the central research facility for the European Fusion Programme and is used by more than 30 different European laboratories and over 350 scientists from the EU, UK, Switzerland and Ukraine.
JET is currently the only fusion reactor capable of working with the mix of deuterium and tritium that’s planned for use in commercial fusion power plants. As a result, it’s at the forefront of the race for commercially viable nuclear fusion and setting the stage for future European fusion research.
EXPERIMENTAL ADVANCED SUPERCONDUCTING TOKAMAK (EAST)
The Experimental Advanced Superconducting Tokamak, or EAST, is another tokamak design that’s been operating in Hefei, China, since 2006 under the authority of the Hefei Institutes of Physical Science and the Chinese Academy of Sciences. Just this January, EAST shattered records by heating its plasma up to 70 million degrees Celsius, or 158 million degrees Fahrenheit, five times hotter than the sun, for over 17 minutes.
In the past, EAST has run even hotter, albeit for much shorter periods of time. In May 2021, it reached 120 million degrees Celsius, or 216 million degrees Fahrenheit, for 101 seconds. Since the core of the sun only reaches a mere 15 million degrees Celsius, or 27 million degrees Fahrenheit, this has led to EAST’s nickname: China’s “artificial sun.”
However, EAST isn’t just China’s. Although the nation will have invested some 1 trillion US dollars in the project by the time it finishes in June, the experiments conducted involve international collaboration and are designed to provide insight for the International Thermonuclear Experimental Reactor, or ITER.
PRIVATE SECTOR COMPANIES
Since the early 2000s, a number of private companies have entered the race to achieve nuclear fusion. There are now over 30 private firms dedicated to fusion, 18 of which have publicly declared their funding, more than 2.4 billion US Dollars in total. The largest of these is Tri Alpha Energy Technologies, or TAE, which was founded in California in 1998 and has roughly $880 million in funding.
More famous, though, might be General Fusion which made headlines after Amazon founder Jeff Bezos invested $130 million in the firm. A Canadian company with headquarters in Vancouver and a total $200 million in funding, General Fusion is building a facility in Culham, Oxfordshire, near JET, that’s designed to be 70% the size of a theoretical commercial plant and demonstrate how one would work. The company claims it will be operational by 2025.
Other leading private firms with hundreds of millions in funding include Helion Energy, Commonwealth Fusion Systems, and Tokamak Energy.
SPHERICAL TOKAMAK FOR ENERGY PRODUCTION (STEP)
The Spherical Tokamak for Energy Production, or STEP, is a fusion reactor planned for the long term by the UK Atomic Energy Authority. The design concept is scheduled for completion in 2024 with construction beginning in 2032 and operation in 2040. It will be a tokamak, but instead of shaped like a donut, it will be a sphere, which means it can be smaller and less expensive, with the British government having announced an initial investment of £200 million, or about 248 million US Dollars.
STEP has lofty goals. The UK Atomic Energy Authority says that once operational, it will be connected to the national electric grid and provide it with hundreds of megawatts of net energy, though it won’t be a commercially operating plant, rather a demonstration of fusion capabilities.
INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER)
The International Thermonuclear Experimental Reactor, or ITER, is the culmination of international cooperation in nuclear fusion research. Many of the other reactors around the world serve as experiments to inform the ultimate design of the ITER. Seven member states founded the megaproject in 2006: China, India, Japan, South Korea, Russia, the United States, and the European Union, meaning a total of 35 nations. The UK also participates through the European Atomic Energy Community.
Together, scientists from all these countries are designing the world’s largest tokamak in Saint Paul-lez-Durance in southern France where construction has been underway since 2010. The reactor is scheduled to achieve its first plasma in December 2025. The operation will then be gradually ramped up until fusion of the deuterium-tritium mixture begins in 2035.
The ultimate goal is for the ITER to produce 500 megawatts of power, more than 30 times that produced by JET. Moreover, it will only require 50 megawatts of input to heat the plasma, giving it a Q factor of 10. It won’t capture this excess power to produce electricity, but it will demonstrate the concepts necessary to achieve net energy gain and pave the way for future power generation.
So is nuclear fusion just around the corner? I suppose it depends on how big the corner is. Nevertheless, one thing is certain. Trillions of dollars and decades of work and research have gone into achieving fusion power with a lot more to come. With so many megaprojects like the ITER combining the ingenuity of people around the world, it definitely seems plausible that sustainable and efficient energy in the form of nuclear fusion is on the horizon.
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