This blog post examines whether humanity can secure sustainable energy through nuclear fusion technology, exploring the current state of research and its potential.
Where does the energy we use come from? Earth receives energy from sunlight, which drives the water cycle, stores heat in the ground, and enables plants to perform photosynthesis. This process acts as an essential element for Earth’s life forms, making the survival of all living things possible. Solar energy also plays a crucial role in regulating Earth’s weather and climate. Thanks to this complex and sophisticated natural system, we can live in a stable environment. We utilize this energy, stored in various forms, to sustain life, create objects, and generate electricity. In other words, the energy we use originates from solar energy. So, how does the Sun obtain its energy? The correct answer is “through nuclear fusion.”
Nuclear fusion is the process where light atomic nuclei combine to form heavier atomic nuclei. The principle behind obtaining energy through nuclear fusion is Einstein’s mass-energy equivalence principle. Simply put, this principle states that mass can be converted into energy, expressed mathematically as E=mc². Here, E represents energy, m represents mass, and c represents the speed of light, which is a very large value at 300,000 km/s. This means a small change in mass can produce a large change in energy. Atoms with atomic numbers 26 or lower lose mass and release energy during nuclear fusion. In the Sun, hydrogen (atomic number 1) undergoes nuclear fusion to generate energy. So, can humanity harness this astonishing energy directly?
High pressure and temperature are required for nuclear fusion to occur. According to Coulomb’s law, the magnitude of the force acting between two charges is inversely proportional to the square of the distance between them. Since atomic nuclei carry a positive charge, the repulsive force between two nuclei increases dramatically as they approach each other for fusion. High pressure and temperature are necessary to overcome this repulsive force. The Sun is extremely large and massive, so the pressure exerted at its core by gravity is immense. This pressure is sufficient to sustain nuclear fusion at temperatures around 15.7 million degrees Celsius at the Sun’s core. Thanks to this immense pressure, the Sun can sustain nuclear fusion stably, continuously supplying energy to Earth. However, on Earth, gravity is weaker, and there are no materials capable of withstanding pressures as high as the Sun’s, making fusion under identical conditions impossible. Yet, if temperatures are raised sufficiently high to compensate for the lower pressure, an environment conducive to nuclear fusion can be created. To achieve fusion power generation on Earth, an environment exceeding 100 million degrees Celsius must be maintained. Yet even carbon, the element with the highest melting point, cannot remain solid beyond just 4,000 degrees Celsius. Is there a vessel capable of containing a substance at 100 million degrees?
To solve this problem, research institutes like Korea’s KSTAR and Europe’s ITER utilize a device called a ‘tokamak’. Tokamak translates to ‘a toroidal container with magnetic coils’. Magnetic coils literally mean coils carrying a magnetic field, and a toroid is a type of electromagnet. An electromagnet is a magnet that applies the principle that a magnetic field is generated around a wire when current flows through it. Unlike conventional permanent magnets, it has the advantage of allowing the magnetic strength to be adjusted as desired by controlling the current intensity. A representative example of an electromagnet is a solenoid, which is an electromagnet made by winding wire like a spring around a material that is easily magnetized, such as iron. A toroid is a solenoid bent into a doughnut shape. When current flows through this toroid, a magnetic field is generated inside it. Tokamaks utilize this to control the extremely high-temperature material within. The reason a magnetic field can control such high-temperature material is because that material is ‘plasma’. When a gas is continuously heated to high temperatures, positively charged atomic nuclei and negatively charged electrons separate, forming a charged gaseous state called plasma. Since charged matter can be controlled by magnetic fields, the tokamak regulates the plasma to prevent it from touching the vessel walls, thereby confining the super-hot material.
The fuel for nuclear fusion power can be obtained from seawater. Using deuterium, a fuel contained in small quantities in 1 liter of seawater, nuclear fusion power generation can produce the same amount of energy as burning 300 liters of gasoline. Seawater, covering approximately 70% of the Earth’s surface, is a vast resource. Utilizing this resource holds the potential to fundamentally resolve the energy challenges facing humanity. Furthermore, the power generation process produces almost no greenhouse gases. Unlike conventional nuclear power plants using nuclear fission, even in the event of an accident, there is no need to worry about risks such as radioactive leaks or explosions. For these reasons, nuclear fusion power is considered the ‘ultimate energy source of the future’.
However, the path to nuclear fusion power remains long. The primary reason is the extreme difficulty in controlling plasma. Plasma is a charged fluid with immense energy, making its properties complex and its motion highly unpredictable. Consequently, predicting and controlling plasma motion is extremely challenging. Plasma motion sometimes exhibits unexpected instabilities, baffling researchers. To solve this, experts from various fields around the world are collaborating on research and experiments. South Korea has also established a technology development roadmap, aiming to achieve commercial fusion power by the 2040s. Through this international cooperation and research, we are gradually increasing the feasibility of nuclear fusion, offering great hope for solving future energy problems.
Nuclear fusion power generation is projected to be feasible in the near future. The tokamak is considered a leading technology for realizing this fusion power. Once tokamak-based fusion power becomes commercialized, nations across the globe will possess a miniature sun within a doughnut-shaped magnet for their citizens. We can look forward to an era of future energy free from concerns about resource depletion and environmental destruction.
