Nuclear Fusion: The Race to Net Energy Gain

By Harrison York

International Collaboration

The International Thermonuclear Experimental Reactor, or ITER, is one of the world’s leading projects for the development of nuclear fusion as an everyday energy source. ITER began construction in 2013 in southern France, with plans to conclude in 2025, when the first plasma tests will take place in ITER’s main tokamak, or specialized fusion chamber. ITER is the realization of the idea for an international collaboration to explore the nuclear fusion process since 1985. 35 nations are currently involved in the megaproject, with the contributing parties being the United States, the European Union, China, India, Japan, South Korea, and Russia. Estimates predict the total cost of the engineering project to be around 20 billion U.S. dollars. The ITER tokamak will have ten times the plasma holding capacity as the largest machine today and will be twice the size. The ITER tokamak has a distinct torus shape, similar to a doughnut, where magnetic fields can contain the plasma. Here, the plasma gains heat until fusion is possible at a temperature about ten times that at the sun's core. Additionally, the tokamak is intended, with time and research, to pave the way for future fusion machines to contribute substantial amounts of energy to the global demand.

One of the main goals of ITER is to create a net energy gain fusion system. Currently, the world record for energy return is just Q = 0.67, meaning that only two-thirds of the energy used in the fusion process was returned. The record is held by the European tokamak JET, which created 16 MW of power by using 24 MW (losing 8 MW in total). Contrastingly, the ITER tokamak is expected to have a Q value greater than or equal to 10, with Q > 1 being a positive energy return. So, Q is the total energy produced by a tokamak (or other machine) divided by the energy put into the machine for its operation. 500 MW is planned to be produced while only consuming 50 MW, an increase by a factor of ten. In achieving this goal, ITER will also complete several other tasks, including developing a method of holding deuterium-tritium plasma for an extended period and testing methods of producing tritium - a hydrogen isotope with two neutrons - within the vacuum vessel, a part of the integrated fusion system. These advancements will collectively push fusion technology closer to realization on a large scale and provide a sort of proof-of-concept to encourage continued investment and funding. But with the first plasma tests set to begin near the end of 2025 and the start of deuterium-tritium fusion around 2035, ITER is not the only group looking to create viable fusion solutions.

Image Credit: Flickr @ Oak Ridge National Laboratory

Private Prospectors

There is also a host of smaller companies and research groups hoping to make breakthroughs in the world of nuclear fusion. One such contender is Tokamak Energy. Tokamak Energy was founded in 2009 and is based in the United Kingdom. With only 50 employees, Dr. David Kingham, one of the company’s executives, believes that fusion will be solved by a private, determined company rather than the ongoing international projects. Interestingly, Tokamak Energy also disagrees with ITER’s work on building a massive tokamak, claiming instead that smaller, compact tokamaks will be more efficient in the long run because of their ability to create denser concentrations of plasma. Like ITER, Tokamak Energy has devised a way to introduce tritium directly into the plasma chamber by utilizing the neutron products of fusion to collide with a lithium blanket and convert those lithium atoms into tritium. Another difference between the two, however, is Tokamak’s employment of high-temperature superconductors to generate a powerful magnetic field. While most tokamaks use either super-magnets (made from special alloys) or electromagnets (made from coils of superconducting materials), Tokamak’s plasma chamber generates its powerful magnetic fields with high-temperature superconducting material cooled by liquid nitrogen. These HTS are gaining recognition in their fusion applications, as another startup company, Commonwealth Fusion Systems, has also begun to use superconductors in their machines. The current high-temperature superconductor industry is small, but the demand for these materials for fusion machines will cause this niche market to expand. Finally, the biggest difference may be Tokamak Energy’s spherical tokamaks, which have “significant physics advantages but greater engineering challenges” (Kingham) compared to the torus-shaped conventional tokamaks. They offer potential for net energy gain systems in the future as well, needing a smaller magnetic field and less space.

With over one billion dollars already invested in fusion prospects in the U.S. alone, the race is only beginning. Worldwide, about 25 such companies exist, each aiming to edge out the competition and help realize this goal of clean, nearly limitless energy. To do this, they have devised complex schemes using lasers, high-powered beams of hydrogen isotopes, and electromagnetic targeting. One thing is sure: when fusion inevitably becomes a real - and profitable - form of energy, the stakes will become much higher than a billion dollars of investment towards research. These smaller companies have their sights set on commercializing fusion as a new form of energy that can be used around the world. Fusion has the potential to turn the energy industry upside-down, allowing for localized fusion reactors to power cities individually with clean, on-demand, and stable energy.

Image Credit: @ skeeze

Comprehension Questions:

1. What are some of the ways that Tokamak Energy differs from ITER?

Tokamak Energy has a very different approach to nuclear fusion compared to ITER. First, it considers smaller tokamak machines more practical and efficient for the future of fusion. Secondly, Tokamak energy uses a lithium blanket to directly introduce tritium into the plasma chamber. The biggest difference is that Tokamak Energy uses spherical tokamaks instead of torus-shaped tokamaks like ITER. Another difference is the way that the two groups operate. ITER is a large, international collaborative organization that receives funding from multiple governments. Tokamak Energy is a private company based in the United Kingdom that seeks to commercialize nuclear fusion. Finally, Tokamak Energy, and other small companies, are using high-temperature superconductors instead of super-magnets and other ways of generating magnetic fields.

2. What does the variable “Q” mean and why is it important?

“Q” represents the net energy gain factor of a fusion system. Specifically, it is the total amount of energy produced by the system divided by the energy put into the system for its operation. It is important because it describes the practicality of fusion: a higher Q value is more desirable than a low Q value. In order for fusion to become a common energy source, Q must be at least greater than 1 (preferably much more). ITER hopes to have a Q of ten, beating the current record of a Q of only 0.67, or two-thirds.


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