For nearly a century, physicists have been attempting to unravel the secrets of nuclear fusion - a reaction that occurs in stars and, scientists hope, could be harnessed to provide us with clean, renewable energy. Several recent breakthroughs in the development of fusion reactors, as well as an increase in investment and research, seem to hint that fusion energy could become viable sometime in the next few decades.
But how does nuclear fusion work? A nuclear fusion reaction is the process where two light nuclei merge to form a single heavier nucleus. During this process, the atoms lose a small amount of their mass, which is released as energy. As Einstein’s equation E = mc2 shows us, mass can be converted into energy, which is precisely what happens during a nuclear fusion reaction (Lanctot, 23).
These reactions typically take place in donut-shaped reactors called tokamaks. Surrounded by superconducting magnets, a tokamak is able to hold plasma fuel in place, where it is heated by microwaves, radio waves, and particle beams. This method of fusion is called magnetic confinement fusion. As nuclear fusion reactions take place within the plasma, heat is captured and converted to electricity (Picot, 2021). Alternatively, inertial confinement fusion is when laser beans are used to compress a small fuel pellet until a fusion reaction occurs, creating a small explosion and generating energy (Lancaster, 19).
Whether a fusion reactor uses magnetic or inertial confinement, it will typically use deuterium-tritium fuel because of its ability to reach fusion conditions at lower temperatures, as well as release more energy when compared to other fuels. It is important to note that both deuterium, which is derived from water, and tritium, which could be created within the fusion power plants, combine to form helium. Helium is not a greenhouse gas and, when released into the atmosphere, escapes into space (Lanctot, 23).
Present-day nuclear power plants perform nuclear fission, which involves splitting atoms apart. During fission, neutrons are fired at an unstable isotope (typically Uranium-235), causing it to break apart and release energy and more neutrons. The neutrons collide with other atoms and continue the process while the energy is captured and converted to electricity (MIT). As nationalgrid.com states “In an emissions sense, nuclear power is considered to be clean. It produces zero carbon emissions and doesn’t produce other noxious greenhouse gases through its operation.” (NationalGrid)
However, nuclear fission is not considered a source of renewable energy, since it requires radioactive fuel. It also produces massive amounts of radioactive waste, 2000 metric tons in the US alone, that is hard to dispose of and can last for hundreds of thousands of years (DOE). At the same time, despite numerous barriers and safety systems, nuclear power plants still pose a threat. The Chernobyl and Fukushima nuclear disasters stand as a testament to the massive amount of damage an uncontrolled fission reaction can cause. Due to safety concerns, many countries, including Germany, Spain, and Switzerland, have started to phase out nuclear fission (WNA, 2022).
On the other hand, fusion is a completely safe process. As the International Atomic Energy Agency states, “given that a fusion reaction could come to a halt within seconds, the process is inherently safe. ‘Fusion is a self-limiting process: if you cannot control the reaction, the machine switches itself off’”. Also, as mentioned before, fusion reactions do not create long-lasting radioactive waste unlike fission reactions (Willis and Liou, 2021).
While nuclear fusion seems like a very promising source of clean energy, until recently, scientists have been unable to create a fusion reaction that actually generated more energy than it consumed. This changed last December when scientists at the Lawrence Livermore National Laboratory (LLNL) in California announced that they had created a fusion reaction that had produced nearly 1.5 times the energy it had used (Bishop, 22). This was a massive leap over previous attempts, and it shows us that nuclear fusion might actually be a viable energy source in the future.
In fact, the amount of attention that nuclear fusion has received has increased massively in the past few years. In 2021, 2.83 billion dollars were invested in private nuclear fusion companies (Thomson, 22). Additionally, congress has begun to take steps to allow for federal permitting of commercial fusion reactors. All of these advancements, as well as recent technological breakthroughs, hint that the creation of the first commercial fusion reactors might be in the not-too-distant future.
Works Cited
“5 Fast Facts about Spent Nuclear Fuel.” Energy.gov, www.energy.gov/ne/articles/5-fast-facts-about-spent-nuclear-fuel#:~:text=The%20U.S.%20generates%20about%202%2C000.
Bishop, Breanna. “National Ignition Facility Achieves Fusion Ignition.” Www.llnl.gov, 14 Dec. 2022, www.llnl.gov/news/national-ignition-facility-achieves-fusion-ignition.
Lancaster, Kate. Inertial Confinement Fusion. 2019.
Lanctot. “DOE Explains...Deuterium-Tritium Fusion Reactor Fuel.” Energy.gov, www.energy.gov/science/doe-explains deuterium-tritium-fusion-reactor-fuel#:~:text=The%20current%20best%20bet%20for.
Lanctot, Matthew. “DOE Explains...Nuclear Fusion Reactions.” Energy.gov, www.energy.gov/science/doe-explains nuclear-fusion-reactions#:~:text=Nuclear%20Fusion%20reactions%20power%20the.
Picot, Wolfgang. “Magnetic Fusion Confinement with Tokamaks and Stellarators.” Www.iaea.org, 2 June 2021, www.iaea.org/bulletin/magnetic-fusion-confinement-with-tokamaks-and-stellarators.
Thomson, Jess. “Can You Invest in Nuclear Fusion Energy?” Newsweek, 13 Dec. 2022, www.newsweek.com/nuclear-fusion-breakthrough-interest-investments-1766757. Accessed 27 Feb. 2023.
Willis, Carley, and Joanne Liou. “Safety in Fusion.” Www.iaea.org, 28 May 2021, www.iaea.org/bulletin/safety-in-fusion.
“What Is Nuclear Energy? | Why Is Nuclear Considered a Clean Energy? | National Grid Group.” Www.nationalgrid.com, www.nationalgrid.com/stories/energy-explained/what-nuclear-energy-and-why-it-considered-clean-energy.