The Search for Renewable Energy: Nuclear Fusion

One of the key areas of science in recent memories is the exploration of new sources of energy. Although there are many avenues being explored across the globe by countless different research and development teams the goal is to meet the world’s energy demands with a renewable but efficient method. Doubtless you are familiar with many of these avenues as they have seen growing usage as time passes. Solar, wind and hydro power are considered to be the vanguard of a new era that brings an end to the need for the ever dwindling supply of fossil fuels. 

Although the aforementioned energy sources are the most well known due to the advancements that have been made in recent years allowing them to see active use, they are far from the only paths being pursued. One such source of energy is still in the earliest stages of its development but shows great promise in its ability to meet the world’s ever growing energy demands in a sustainable manner. This source is nuclear fusion.

What Is Nuclear Fusion?

Although the term “nuclear” has likely conjured up images of glowing uranium the process of fusion is markedly different to that of fission which is carried in nuclear plants today.

Nuclear fission is the process of splitting the atom to generate heat. In nuclear power plants this is then used to convert water into steam in order to turn turbines.[1] Fusion on the other hand is the process of fusing low mass nuclei into an element with a higher mass nucleus and a release of energy.[2] This same process is carried out by our own Sun and produces an energy output about four times greater than fission reactions of the same mass.[6]

Figure 1: Process of Nuclear Fusion

Source: https://www.energy.gov/science/doe-explainsnuclear-fusion-reactions

Although there are numerous different fusion reactions, the one being explored at the moment is that of deuterium and tritium thanks to its higher release of energy than in other fusion reactions.[3] It also boasts a variety of other advantages over the more contentious process of fission. Instead of the uranium isotopes needed to fuel a fission process, the hydrogen isotopes of deuterium and tritium are employed. These particular sources of fuel have the added benefit of being virtually limitless with tritium being able to be created during the reaction and deuterium being abundant in seawater.[2]

The risk of a catastrophic failure that has long hung over the head of nuclear power is also mitigated by fusion. Rather than a nuclear meltdown as observed in the past, any failure in the fusion process simply would see the process end. Although this does boast a higher degree of safety it is also what makes the reaction difficult to sustain in a controlled manner.[2] The conditions for fusion are demanding, requiring intense pressure and temperatures exceeding 100 million degrees Celsius are required alongside a suitable confinement to hold the created plasma. 

Who Is Researching Nuclear Fusion?

The International Atomic Energy Agency, an agency within the UN, is responsible for promoting safety and security for nuclear technology. As such the research into nuclear fusion has fallen under their jurisdiction. Research is currently being carried out in 50 of the agency’s member states in order to make the energy source a reality.

The ITER(International Thermonuclear Experimental Reactor) is currently under construction in Cardiche, France. It will be the world’s largest and most advanced fusion experiment with projections giving it the ability to produce 500 Megawatt of fusion power. 

Figure 2: ITER Visualization by Jamison Daniel

Source:https://www.iter.org/proj/inafewlines

Another experiment designed to run in tandem with ITER is also set to begin construction this year.[5] The IFMIF(International Fusion Materials Irradiation Facility) is an experiment to test materials that are capable of withstanding the harsh conditions conducive to nuclear fusion.

How Close Are We To Achieving Fusion?

The truth is that nuclear fusion, in spite of the promise it shows, is still a long way from being viable. Although the conditions for nuclear fusion are able to be created reliably in experiments today, the containment of the resulting plasma has to be improved to maintain the reaction for any length of time.[4] 

However, recently there have been strides in the progress being made.In February of this year the UK based laboratory JET has broken its world record for the amount of energy produced by fusion. The facility was able to produce 59 megajoules of energy over 5 seconds. This improvement was due to the construction of new walls for the reactor. Rather than the previously utilized carbon which absorbs tritium, the walls were made from beryllium and tungsten which was found to be 10 times less absorbent.[7]

A similarly impressive breakthrough was made in MIT by scientists Pablo Rodriguez-Fernandez and Nathan Howard who were able to use machine learning in order to predict the temperature and density profiles of plasma in fusion conditions. They were able to vastly reduce the CPU time for the solution while not sacrificing accuracy despite the brute force calculation being beyond the ability of the world’s most advanced supercomputers.[8]

With ITER set to commence its experiment in 2025 and the recent advancements made in the field, the future of nuclear fusion is seeming to be more likely with each passing day.

References

[1] Nuclear Explained, US Energy Information Administration
https://www.eia.gov/energyexplained/nuclear/nuclear-power-plants.php

[2] How fusion breakthroughs will lead to clean renewable energy, HORIBA Scientific

https://www.horiba.com/int/science-in-action/how-fusion-breakthroughs-will-lead-to-clean-renewable-energy/

[3] DOE Explains…Nuclear Fusion Reactions, Office of Sciences

https://www.energy.gov/science/doe-explainsnuclear-fusion-reactions

[4] I. Chatzis & M. Barbarino, What is Fusion, and Why Is It So Difficult to Achieve?

https://www.iaea.org/bulletin/what-is-fusion-and-why-is-it-so-difficult-to-achieve

[5] IFMIF-DONES

https://ifmifdones.org/dones-updates/escuzar-city-council-and-ciemat-sign-land-transfer-agreement-for-the-construction-of-ifmif-dones/

[6]Advantages of Fusion

https://www.iter.org/sci/Fusion#:~:text=Abundant%20energy%3A%20Fusing%20atoms%20together,reactions%20(at%20equal%20mass).

[7] J. Amos, Major breakthrough on nuclear fusion energy

https://www.bbc.com/news/science-environment-60312633

[8] M. Greenwald, Machine learning, harnessed to extreme computing, aids fusion energy development

https://news.mit.edu/2022/machine-learning-harnessed-extreme-computing-aids-fusion-energy-development-0427