Nuclear Fusion is a process in which two lighter atomic nuclei combine to form a heavier nucleus, and releasing energy. This is the same process that powers stars like our Sun. Devices designed to harness this energy are known as fusion reactors.
As a source of power, nuclear fusion is expected to have several advantages over fission. These include reduced radioactivity in operation, little nuclear waste, ample fuel supplies, and increased safety. However, controlled fusion has proven to be extremely difficult to achieve in a practical and economical manner. Research into fusion reactors began in the 1940s, but to date, no design has produced more power output than the electrical power input. Therefore, all existing designs have had a negative power balance.
Fusion reactions occur when two or more atomic nuclei come close enough for a sufficiently long enough time, such that the nuclear force pulling them together exceeds the electrostatic force pushing them apart, fusing them into heavier nuclei. For nuclei lighter than iron-56, the reaction is exothermic, releasing energy. For nuclei heavier than iron-56, the reaction is endothermic, requiring an external source of energy. Hence, nuclei smaller than iron-56 are more likely to fuse while those heavier than iron-56 are more likely to break apart.
The strong force acts only over very short distances. The repulsive electrostatic force acts over longer distances. In order to undergo fusion, the fuel atoms need to be given enough energy to approach each other close enough for the strong force to dominate. The amount of kinetic energy needed to bring the fuel atoms close enough is known as the “Coulomb barrier”. Ways of providing this energy include speeding up atoms in a particle accelerator or heating them to high temperatures.
Once an atom is heated above its ionization energy, its electrons are stripped away (it is ionized), leaving just the bare nucleus (the ion). The result is a hot cloud of ions and the electrons formerly attached to them. This cloud is known as plasma. Because the charges are separated, the plasma is electrically conductive and magnetically controllable. Many devices take advantage of this to control the particles as they are heated.
Fusion Energy- Advantages
Comparing to other fuel-consuming energy sources currently in use, fusion power would provide more energy for a given weight of fuel. More importantly, the fuel (deuterium), exists abundantly in the Earth’s ocean.
Despite being technically non-renewable, fusion power has many of the benefits of renewable energy sources, such as-
- Long-term energy supply with no greenhouse gas emission or air pollution.
- Another aspect of fusion energy is that the cost of production does not suffer from diseconomies of scale. With fusion energy, the production cost will not increase much even if large numbers of stations are built, because the raw resource (seawater) is abundant and widespread.
- Fusion power could be used in interstellar space, where solar energy is not available.
- The natural product of the fusion reaction is a small amount of helium, which is completely harmless to life.
Fusion Energy- Disadvantages
Some problems that are expected to be an issue are-
- Freshwater shortages can alternatively be regarded as problems of energy supply.
- The reaction process is so delicate that this level of safety is inherent.
- Commercial power plants would be extremely expensive to build.
- Requires extremely high temperatures.
- Could produce a net negative amount of energy.
- Would remove any incentive for restraint in the use of energy.
Video Courtesy – ” Kurzgesagt – In a Nutshell ”