La nuclear energy has played a crucial role in the world's energy supply for decades. However, energy derived from the nuclear fusion promises an even more significant change in the energy landscape, offering a virtually inexhaustible resource with minimal emissions of radioactive waste. Despite its potential, this fantastic process is still in development, as the technological and economic difficulties are not minor. It is a challenge that scientists around the world are continually investigating in order to make nuclear fusion a reality as a stable commercial energy source one day.
In this article, we will delve into what nuclear fusion is, its benefits, the challenges to making it a commercial source, and its importance for the global energy future.
Which is nuclear fusion?
Nuclear fusion is a different process from nuclear fission, which is the mechanism used in current nuclear power plants. While fission involves splitting heavy atoms, such as uranium and plutonium, fusion involves joining lighter nuclei, such as hydrogen atoms, to form a heavier, more stable one. The result of this union releases a large amount of energy in the form of heat.
The most feasible process so far is the fusion of deuterium and tritium, two isotopes of hydrogen, to form helium. During this reaction, particles such as neutrons are also released. In the case of deuterium-tritium fusion, 17.6 MeV (million electron volts) are released per fusion reaction. This energy is considerably higher than that obtained in nuclear fission.
One of the main advantages of nuclear fusion is that deuterium can be extracted from seawater, making it almost unlimited in terms of fuel supply. On the other hand, tritium, although not as abundant as deuterium, can be generated in the fusion reactors themselves by bombarding lithium with neutrons.
How is nuclear fusion done?
Achieving nuclear fusion on Earth involves reproducing extreme conditions similar to those found in the core of stars. In order for atomic nuclei to fuse, they must overcome the natural electrostatic repulsion between them, and to do so they need to reach temperatures of millions of degrees Celsius.
In experimental reactors such as Tokamaks and Stellarators, atoms are heated to over 100 million degrees to generate enough speed and energy for nuclei to come close enough to one another and fuse. At these temperatures, matter is no longer in a solid, liquid or gaseous state, but in a plasma state, an ionized gas of charged particles.
The main problem with fusion is that there is no material on Earth that can withstand such high temperatures without melting. Therefore, in fusion reactors, the plasma must be confined by powerful magnetic fields that prevent it from touching the reactor walls. This is the approach of magnetic confinement, which consists of holding the plasma within a toroidal (ring-shaped) geometry using superconducting magnets.
Another approach is inertial confinement, where lasers or particle beams are used to compress tiny deuterium-tritium capsules to extremely high densities, causing the particles to fuse before they have time to expand. A notable example of this approach is the National Ignition Facility (NIF) in the United States, which has achieved important milestones in inertial fusion research.
Scientific containment strategies
There are two main techniques for attempting to achieve controlled nuclear fusion: magnetic confinement and inertial confinement.
Magnetic confinement: This method is based on using powerful magnetic fields to contain the hot plasma. In a reactor tokamakFor example, toroid-shaped magnets are responsible for keeping the plasma away from the reactor walls, allowing the fusion process to occur without the plasma cooling too quickly.
One of the biggest challenges with this technique is that only a fraction of the particles in the plasma manage to fuse. For fusion to be economically viable, more than 50% plasma efficiency must be achieved, known as Lawson criterionAlthough the Sun uses gravitational confinement due to its enormous mass, on Earth we cannot replicate those pressures, so we need to reach much higher temperatures.
Inertial confinement: Instead of containing the plasma with magnetic fields, inertial confinement proposes using lasers or particle beams to compress capsules of deuterium and tritium. The idea is that by compressing these capsules to extremely high densities and then rapidly heating them, fusion will be triggered before the particles can move too far.
Both approaches have their advantages and disadvantages, and scientists are still investigating which approach will enable the commercial viability of fusion reactors.
When will it be commercially viable?
Despite the advances made in recent decades, nuclear fusion is still a few decades away from being commercially viable. It is estimated that it could be possible to see the first commercial nuclear fusion reactors around 2050, although this date depends largely on technological advances and continued research funding.
However, one of the most promising projects is the ITER (International Thermonuclear Experimental Reactor), an international effort that aims to demonstrate the technical and scientific feasibility of nuclear fusion through magnetic confinement. If successful, ITER tests are expected to pave the way for the creation of commercial fusion-based reactors.
Another significant advance has been the development of high temperature superconductors for magnets used in fusion reactors. MIT researchers have developed a superconducting magnet that generates magnetic fields much more powerful than traditional magnets, while consuming much less energy. According to the studies, this technology could reduce the cost of fusion reactors by a factor of 40, making commercial fusion not only viable, but potentially cost-competitive.
Making fusion a reality requires not only scientific breakthroughs but also broader international collaboration and political and financial commitment to support long-term research. Fusion has the potential to be a clean, safe and virtually unlimited source of energy, but it requires sustained investment and coordinated effort at a global level.
Nuclear fusion holds immense energy promise that would address many of the problems facing our civilization in terms of sustainability and energy security. However, the scientific, technical and logistical challenges facing this technology are enormous. As research progresses, it is hoped that in the coming decades, fusion could finally move from the laboratory to become part of the world's energy supply.