In this blog post, we’ll explore why fusion energy is called the “energy of our dreams,” focusing on its principles, advantages, the current state of research, and its potential as a future energy source.
The Principles of Fusion Energy and the Birth of the Artificial Sun
The Sun is an essential source of energy that powers all systems on Earth, including ecosystems, atmospheric systems, and oceanic systems. Through the radiant energy from the Sun, plants perform photosynthesis, animals utilize light and heat, and the atmosphere and ocean currents circulate. The Sun can be said to be the source that sustains all life on Earth. What if we could generate solar energy—a blessing to all living things—directly here on Earth? The fields of science and technology driving research to turn this dream into reality are plasma physics and nuclear fusion engineering. Researchers in these fields are continuing their work to create an artificial sun on Earth, motivated not only by pure scientific curiosity but also by a sense of mission to ultimately solve the increasingly serious energy crisis. In this article, we will explain the principles of nuclear fusion energy—the Sun’s energy source—and examine the potential for nuclear fusion energy to become a crucial future energy source capable of resolving the energy crisis.
In the early 20th century, scientists discovered that the source of the Sun’s energy is the mass-loss energy generated by nuclear fusion reactions. A nuclear fusion reaction is a process in which atomic nuclei with low atomic numbers combine to form a single, heavier atomic nucleus. The mass-loss energy generated by nuclear fusion reactions occurring at the Sun’s core maintains the temperature of each region within the Sun and supplies energy to Earth. The energy generated at the core is transmitted to the Sun’s surface through the radiative and convective zones and is emitted into space from the photosphere in the form of radiant energy. This is the energy we call sunlight.
While solar thermal and photovoltaic power generation—which utilize the energy contained in sunlight—are important energy technologies, some scientists have researched methods to directly harness the energy generated by nuclear fusion reactions, rather than utilizing solar radiation energy through multiple intermediate steps. This method of power generation is called nuclear fusion power generation.
Nuclear fusion reactions can only occur when atomic nuclei come very close to one another. However, since all atomic nuclei carry a positive charge, an electrical repulsive force exists that pushes them apart. To overcome this, the kinetic energy of the atomic nuclei must be sufficiently high to overcome the electrical repulsion, which requires extremely high temperatures. In such ultra-high-temperature environments, matter exists not in its normal gaseous state but as plasma, in which atomic nuclei and electrons are separated.
For a massive star like the Sun to sustain nuclear fusion reactions continuously, the plasma must be maintained at a high density. However, since plasma tends to spread easily toward areas of lower density, technology to confine it is essential. In the Sun, the powerful gravitational force generated by its immense mass performs this role, a process known as gravitational confinement.
On Earth, however, since we cannot generate gravity comparable to that of the Sun, alternative methods are required. Currently, the primary methods of confining fusion plasma are magnetic confinement and inertial confinement. Magnetic confinement utilizes the property of charged particles rotating and moving along magnetic field lines within a strong magnetic field, while inertial confinement involves irradiating the fuel from all directions with lasers or particle beams to instantaneously compress it, thereby maintaining a balance between the compressive force and the plasma’s expansion force during the fusion reaction.
Based on research findings to date, magnetic confinement is the most actively studied method, and the international fusion project ITER (International Thermonuclear Experimental Reactor) is also being developed based on the tokamak, a magnetic confinement device.
Why is nuclear fusion attracting attention as a future energy source?
We have examined the principles of nuclear fusion energy and plasma confinement. So why is nuclear fusion attracting attention as a key energy source for the future? Research on nuclear fusion is receiving even greater attention as the potential depletion of fossil fuels and the issue of climate change have emerged as critical challenges for the international community. Currently, various renewable energy sources and nuclear power are being discussed as alternatives to fossil fuels, but each faces its own challenges.
The most significant characteristic of renewable energy is that, due to the physical properties of the energy source itself, there are inherent limits to the amount of energy that can be produced per unit area or volume. Solar photovoltaic and solar thermal energy are constrained by the intensity of solar radiation, and wind power is also affected by wind density and speed. Tidal, geothermal, and bioenergy are also subject to their own environmental constraints.
Of course, the efficiency of renewable energy is steadily improving thanks to technological advancements, and its share of the global electricity supply is rapidly increasing. However, there remains the challenge that meeting large-scale energy demand reliably requires vast tracts of land, energy storage systems, and the construction of transmission grids.
Furthermore, renewable energy is often limited in the areas where it can be installed. Wind power requires suitable wind conditions, tidal power requires specific topographical conditions, and bioenergy requires land and climatic conditions suitable for raw material production. Solar power also requires extensive installation space.
From an environmental perspective, while renewable energy is more eco-friendly than fossil fuels, it is not entirely free of environmental impacts. Wind power has raised concerns regarding noise and bird collisions, while solar power requires environmental considerations during the development of large-scale sites as well as in the manufacturing and disposal of panels. Therefore, continuous technological improvements are being made to minimize the environmental impact of renewable energy as well.
Now, let’s take a look at nuclear energy. Nuclear power can largely compensate for the various limitations of renewable energy discussed earlier, as it can produce a very large amount of energy per unit area. However, nuclear power carries the risk of radioactive material spreading over a wide area in the event of a major accident. The Chernobyl and Fukushima nuclear accidents are prime examples illustrating this risk. Of course, the safety of nuclear power plants has greatly improved thanks to continuous technological advancements and stricter safety regulations; however, concerns about safety persist due to the immense social and environmental impact that would result from an accident.
Advantages and Commercial Viability of Fusion Energy
For the reasons discussed so far, both renewable energy and nuclear power have their respective advantages and limitations. In contrast, fusion energy has the advantage of producing a very high amount of energy per unit volume, while significantly addressing the limitations of renewable energy and the risks associated with conventional nuclear power. For this reason, fusion is regarded as a key energy source for the future.
Since fusion also utilizes mass deficit energy, it possesses a very high energy density. However, unlike conventional nuclear power generation, which relies on fission, fusion reactions are characterized as non-self-sustaining, or non-spontaneous, reactions. In other words, if the ultra-high-temperature plasma state cannot be maintained, the fusion reaction stops immediately.
In magnetic confinement systems, powerful magnetic fields and various heating devices are used to sustain the plasma. All of these devices require an external power supply. Therefore, if the power supply is interrupted or control is lost, the plasma cools rapidly and the fusion reaction naturally ceases. This is why the likelihood of a runaway chain reaction—a major concern in conventional nuclear power generation—is extremely low.
The inertial confinement method also involves repeatedly compressing very small fuel pellets instantaneously to trigger nuclear fusion, followed by replacing them with new fuel; thus, the possibility of a major accident caused by a chain reaction is virtually nonexistent. Due to these characteristics, nuclear fusion is regarded as a power generation method that is inherently safer than conventional nuclear power.
Furthermore, although radioactive materials are produced during the fusion power generation process, the volume of radioactive waste and the long-term management burden are generally expected to be relatively lower than those associated with spent nuclear fuel from fission power generation. However, since the structural materials of the reactor are activated by neutrons, it is not the case that no radioactive waste is produced at all.
Fusion also offers significant advantages in terms of fuel. Deuterium, the primary fuel for fusion, is abundant in seawater. Currently, the most feasible fusion method is D-T fusion, which uses deuterium and tritium; tritium can be produced from lithium. Research is also underway on fusion methods that use only deuterium or other fusion mechanisms, so the prospects for securing fuel are expected to improve as the technology advances.
These characteristics—high energy density, excellent safety, and abundant fuel resources—are precisely why nuclear fusion has long been called the “dream energy.”
There is also no shortage of skepticism regarding nuclear fusion energy. This is because, although predictions that nuclear fusion would “soon be commercialized” have been repeated for decades, no commercial power plants are yet in operation. However, a review of recent research findings reveals that this skepticism is beginning to shift.
The primary reason fusion research has progressed more slowly than expected since the mid-20th century is the instability of plasma. In magnetic confinement systems, large amounts of plasma must be maintained stably for extended periods; however, plasma has a tendency to become unstable even with minor disturbances. Consequently, the central challenge in fusion research to date has been understanding and controlling this instability.
Currently, plasma control technology is continuously improving thanks to rapid advancements in plasma turbulence analysis using ultra-high-performance supercomputers and AI-based control technologies. Furthermore, in fusion research, the ratio of energy produced to energy input is referred to as the Q-value; recently, the U.S. National Ignition Facility (NIF) garnered global attention by achieving a scientific energy gain (Q > 1) in the inertial confinement approach. Various international research projects, including the ITER project, are also underway in the magnetic confinement approach, and countries are continuing their research with the goal of developing demonstration reactors (DEMO) and commercial fusion power plants following ITER.
Although commercial fusion power generation is not yet at the stage of immediate realization, technological progress is advancing very rapidly compared to the past, and research for the construction of actual power plants is also proceeding steadily.
Can nuclear fusion change the future of humanity?
We have examined the reasons why nuclear fusion energy has garnered attention as a future energy source. Research into nuclear fusion power is a highly challenging field that seeks to replicate the Sun—the source of Earth’s energy—on Earth. Although the history of global fusion research has included periods of difficulty due to budget cuts and a lack of public interest, researchers have steadily advanced the technology. As a result, it has now established itself as a core research field in which countries around the world are making large-scale investments.
South Korea is also playing a significant role in the field of fusion research. The Korean Superconducting Tokamak Advanced Research (KSTAR) is leading international fusion research by continuously breaking world-class plasma operation records. As a key participant in ITER, South Korea is developing various core components and is actively involved in the development of next-generation fusion power technology.
It is thanks to the tireless efforts of countless researchers that South Korea—which had a relatively weak foundation in fusion research just a few decades ago—has grown into a world-class leader in the field. Fusion research began with the grand dream of creating an artificial sun. Although this goal seemed impossible for a long time, researchers did not give up, and today we have reached concrete stages toward commercialization.
While fusion power generation still faces technical challenges that need to be resolved, it is highly likely to play a crucial role in solving humanity’s energy problems if sustained research and international cooperation continue. If an era ever dawns in which humanity can stably generate and utilize the Sun’s energy on Earth, fusion will be the technology at the heart of it.
