To counter the climate change, we must change the way we produce and consume. The challenge of decarbonization consists in the adoption of an economic model that drastically cuts the greenhouse gas emissions. In this transformation, thefusion energy it could one day play an important role by effectively integrating intermittent renewable sources such as solar and wind. A turning point that however implies a technical challenge yet to be won.
The merger process is in fact based onunion of light atoms (as isotopes of hydrogen) thanks to very high temperatures, but the technology that must manage this physical reaction, which releases enormous quantities of energy, is not yet ready. This is the Tokamak and it is the device on which research in this area is focusing the most. Consisting of a donut-shaped high vacuum chamber, it is precisely inside it that we will try to reproduce the physical reaction of the fusion, which is the same process that powers the Sun and the other stars. A phenomenon that generates a lot of energy: according to the estimates ofInstitute of Electrical and Electronics Engineersa single gram of hydrogen isotopes can produce the same amount of energy as eleven tons of coal.
How Tokamak Works
It is very difficult to replicate the fusion process that occurs in the Earth on Earth Sole, where hydrogen nuclei join together, forming helium and releasing energy. This is because, on Earth, in the absence of the immense gravitational forces that favor fusion in the center of the stars, it is necessary bring hydrogen isotopes to over 100 million degrees. At those temperatures, once the plasma state is reached, the hydrogen isotopes can fuse to release energy. The technical obstacle concerns precisely the management of plasma, the fourth state of matter: the problem consists not only in obtaining the right temperatures, but also in confining the plasma in a confined space and sustaining it over time. Finally, it is complex to collect the energy generated, transforming it into electricity.
The magnetic confinement fusion is one of the most studied methods to carry out this process and is based on the use of Tokamak, a device in which, thanks to a powerful magnetic field produced by supermagnets placed around the chamber, it is possible to confine and sustain the plasma at a temperature of 100 million degrees (about 10 times that of the Sun’s core). The plasma orbits inside the tokamak without coming into contact with the walls.
To ignite a fusion reactor, you enter the Tokamak a mixture of deuterium and tritium, two isotopes of hydrogen: the first is obtained from sea water, the second is produced by a physical reaction with lithium. To reach high temperatures, a series of internal and external heating mechanisms are adopted. On the one hand, it is the magnetic fields that produce heat, heating the plasma. On the other hand, through the technique ofinjection of neutral beams, heat is introduced through neutral particles. The plasma state and fusion conditions are thus achieved. The process releases very energetic neutrons, which are absorbed into a “blanket”: a thick coating that surrounds the melting chamber and which contains a molten salt.
There are several development and innovation projects currently underway around the world, such as public projects such asInternational Thermonuclear Experimental Reactor (Iter) in the South of Francelo Spherical Tokamak For Energy Production (Step) of the Wired in Great Britain andExperimental Advanced Superconducting Tokamak in Chinese.
To these are added several private projects including those of the company Tokamak Energy a Oxford (Uk) e you Commonwealth Fusion Systemsa spin-off company of Massachusetts Institute of Technologyof which Eni has been a shareholder since 2018 and actively collaborates with to complete the assembly of the experimental Tokamak Sparc by 2025.