What is nuclear fusion? | Earth.Org – Past | Gift


The Joint European Torus (JET), the largest tokamak (a strong magnetic field to confine the plasma in the form of a torus) located in Oxfordshire, is a machine that generates energy by controlling nuclear fusion. He recently made a breakthrough in an experiment by producing 59 megajoules of electricity in five seconds, doubling the previous record from 1997 and marking a milestone in the history of the development of nuclear fusion technologies. The recent breakthrough shows that we are on the verge of commercializing energy production with nuclear fusion, a relatively “utopian” thought at the time, and potentially having a new sustainable energy source.

Nuclear fusion versus fission

The world is relatively familiar with the concept of nuclear fission, which is known to be the reaction necessary to produce nuclear energy. Nuclear fission is the process in which the nucleus of an atom is split into several smaller and lighter nuclei and generates energy. On the other hand, nuclear fusion is a relatively new concept, largely confined within the scientific community because it is not yet a commercialized method of producing nuclear energy. In a nutshell, nuclear fusion is the exact opposite of nuclear fission; instead of splitting, several smaller, lighter nuclei such as hydrogen combine to form a heavier nucleus such as helium, which produces significant energy in the process. In other words, nuclear fusion generates energy by combining nuclei instead of dividing them.

By forcing the nuclei to combine, they experience repulsion under the law of electrostatic force. To overcome the repulsion of the nuclei, the nuclei must be in the form of plasma, the fourth state of matter after solid, liquid and gas. And to create plasma, you need an environment of extremely high temperature, extremely high density, and/or extremely high pressure; an environment much like the core of the sun.

The attempt to manipulate the merger

Today, scientists have found two ways to fuse nuclei. The first is called magnetic confinement fusion. JET is one of the examples that adopts this method to generate nuclear fusion energy. As mentioned, an extremely high temperature is required to initiate fusion. Inside JET, the plasma must be at least heated above 150 million degrees Celsius to achieve fusion. However, there is currently no material in the world capable of withstanding this temperature without deteriorating. To solve this problem, the scientists developed a method to push the plasma away from the walls of the device by using a huge magnetic field to confine the movement of the plasma. Perhaps the most efficient magnetic configuration is the tokamaka donut-shaped torus in which the magnetic field is curved to form a closed loop.

Another method for fusing nuclei is inertial confinement fusion. The National Ignition Facility located in California in the United States is the most advanced device which experiments fusion by inertial confinement. This method is relatively simple; it initiates fusion by rapidly compressing and heating the fuel to make it hot and dense enough to overcome the repulsion of the cores and the fuse, usually using a high-powered laser beam.

Preamplifier at the National Ignition Facility. Image by: Wikimedia Commons

Why is nuclear fusion considered “utopian”?

Nuclear fusion is clean: No greenhouse gases or air pollution are emitted during nuclear fusion. The main by-product of fusion is helium, an inert, non-toxic gas. Helium, on the contrary, is a very useful chemical element whose supply is insufficient. It is widely used in the aerospace and cryogenic industries. If it can be collected during smelting, it will be another spin-off perk. Although some nuclear waste is produced during the fusion process, its radioactivity is much weaker and lasts much less time than the nuclear waste produced during nuclear fission. For waste produced by conventional nuclear reactors, radioactive decay can take 1,000 to 10,000 years. However, the activity of waste from nuclear fusion declines rapidly in 100 years.

Nuclear fusion is sustainable. It is arguably the most sustainable method of generating energy. Most nuclear fusion research is currently devoted to deuterium-tritium fuel. Deuterium is an isotope of hydrogen found abundantly in seawater while tritium is another rare and radioactive isotope of hydrogen. Yet scientists have found a way to produce tritium manually, sustainably. It was found that by adding a layer consisting of lithium surrounding the reactor, it will produce tritium as a by-product during nuclear fusion. Lithium is the 33rd the most abundant chemical element on Earth, widely distributed in trace amounts in soils and often used in the production of electric vehicle batteries; its abundance can ensure sustainable energy production from nuclear fusion. Moreover, the fuel required for nuclear fusion is so small that a gallon of seawater can produce as much energy as 300 gallons of gasoline if we can completely manipulate it.

Nuclear fusion is safe. The idea of ​​building a sun on Earth may seem dangerous. But on the contrary, nuclear fusion is one of the safest methods to produce energy. Since nuclear fusion does not involve a chain reaction like nuclear fission, the plasma will simply expand, cool, and eventually shut down if containment fails. It will therefore not explode under any circumstances and lead to catastrophic nuclear disasters due to environmental reasons, military actions or terrorism. It also poses no risk of nuclear proliferation, as the materials needed to manufacture nuclear warheads such as uranium will not be found in these reactors.

The future of nuclear fusion

Despite all the benefits, what’s the catch? Nuclear fusion is still underdeveloped today. In order to create fusion, the fuel must be heated to at least one hundred million degrees Celsius. The energy expended to maintain the reaction is far greater than the energy produced by the energy. For example, JET needs 24 megawatts of input to create 16 megawatts of output.

No one can guarantee that nuclear fusion can be commercialized in a short period of time, and the cost of creating nuclear fusion and the power plant remains incredibly high. International Thermonuclear Experimental Reactor (ITER), an international project working on fusion, is located in Saint-Paul-lez-Durance, France. Its construction began in 2007 and should have its first plasma at the end of 2025. Its design and construction cost at least 22 billion US dollars. While extremely high costs are the result of underdevelopment, critics of nuclear fusion describe ITER as a “white elephant” and argue that money is better spent on the development of renewable energies that have already proven themselves.

However, we must not forgo any potential alternative to achieving sustainable energy, as every notable method of energy production was expensive before it was commercialized. Also, in economics, there is a term called the law of diminishing marginal returns, which means that an additional factor of production will eventually cause a smaller increase in output after reaching the optimum level of output. Many resources are already devoted to the development of renewable energies, but we are at a bottleneck. Resources should be allocated to multiple projects at the same time to minimize the risk of one failing. All eyes are on ITER to determine whether nuclear fusion remains a utopian fiction or the future of energy production.

Image selected by: Wikimedia Commons


Comments are closed.