A Practical Analysis of Fusion Energy in 2022 by Evan Harbaugh
I. Introduction
Fusion energy has the potential to revolutionize the entire energy ecosystem. Since the introduction of general relativity, scientists have sought to harness the power of atoms. However, despite early optimism about the feasibility in designing sustainable fusion reactors after the 1940s, it remains an unsolved endeavor to this day. Fusion is the source of energy that powers the stars, where the force of gravity is so strong that individual atoms are smashed together, and the byproduct is a new element and enormous amounts of energy. There are an outstanding amount of engineering challenges that go into building a fusion reactor, and despite them, there have been numerous reactors that have been able to achieve fusion reactions. The primary challenge is producing a sustained reaction, or one where the generator produces more energy than it takes to start. Recently, a new reactor was able to achieve a 70% energy output versus the input energy, which marks a dramatic increase in efficiency (Rincon, 2021). It was this development that spurred my curiosity to investigate the feasibility of fusion reactors, and research what the global implications are if these recent developments lead to widespread production of efficient and sustainable fusion reactors.
II. Literature Review
Although stars are constantly demonstrating the power and efficiency of fusion reactions, trying to replicate the process on earth is an enormous challenge that requires precise mathematics and extremely hot temperatures. Early applications for fusion technology were found in weapons, but researchers also sought to utilize the technology for scientific research, and as a source of commercial electrical power. Scientists have been hopeful about the development of fusion generators as a power source for decades, but for each iteration of designs, the technology to make it possible always seems to be just out of reach. This literature review will look at some of the technological advancements in the discipline, the challenges researchers are facing, and the barriers that still remain to fusion energy being a power source on electric grids.
It’s worth noting at this point, that there are two technologies that are the current frontrunners for fusion reactors. They both work by heating and compressing materials, but differ in their methods to do so. One design is doughnut shaped and uses a technology called magnetic confinement. The other is spherically shaped, and relies on a technology called inertial confinement. Our first source for this literature review from Rinderknecht et al. (2021) studied quantum-electrodynamic physics, in a way that relates to inertial confinement, with the Texas Petawatt Laser, and examines a phenomenon called relativistically transparent magnetic filaments (Rinderknecht et al., 2021). Relativistically is a description of the speed of particles, that they are moving so fast that their speed changes their physical characteristics. (An example would be if an element has a lifespan of 1/100 of a second, but when driven in a particle accelerator at close to the speed of light has a lifespan of over 1/100 of a second. That’s a theoretical explanation, but ultimately the point is that conventional science and physics change when approaching the speed of light.) The experiments looked at how particles interacted with the laser, in particular how the laser interaction generated a magnetic field that captured and propelled electrons in a way that could increase laser effectiveness (Rinderknecht et al., 2021). The study examined how this interaction could allow lasers to alternate in scale, and still produce consistent results.
Our second source for this literature review from Kawata (2021) offers a more in-depth view of actual fusion reactors, but also focuses on inertial confinement technology with lasers. In this study, it wasn’t just an induced magnetic field that is described to increase the efficiency of the lasers, but the physical rotation of the lasers themselves (Kawata, 2021). As mentioned earlier, inertial confinement reactors are spherically shaped. They have lasers symmetrically placed along each axis of the sphere, and all focus to the exact center of the sphere where they blast a fuel pellet “in a few tens of nanoseconds” to cause a fusion reaction (Kawata, 2021). The author points out how despite the precision of the systems, the reaction can be adversely impacted by uneven heating of the fuel pellet. They show research that demonstrates how lasers that rotate, or “wobble,” cause a more even heat distribution, and increase the efficiency of the reaction (Kawata, 2021).
Our next source for this literature review from Castro et al. (2021) changes gears, and now moves to magnetic confinement technology. Instead of the previous examples that use lasers to compress particles, this technology uses magnets. Each technology has advantages, the reason inertial confinement has gained more momentum recently over magnetic confinement is its efficiency. The lasers only have to fire for a fraction of a second to produce a reaction, whereas magnetic confinement reactors have to supply constant power to high powered magnets. This is the area where the study looks to address. It examines how properties of lithium have the potential to increase the efficiency of magnetic confinement reactors, and how the reactors could be smaller and more commercially viable (Castro et al., 2021). A main point within the research was addressing the thermal boundary of high energy lithium in Tokamak reactors. Lithium can create a focused and narrow band of plasma inside of a reactor, which is ideal for two reasons. The first is that this property would allow reactors to operate with a smaller construction footprint. The second is that the tight thermal boundary reduces irregularities and creates a more efficient, sustained reaction (Castro et al., 2021).
Tokamak reactors are what most people picture when they think of a fusion reactor. They’re doughnut shaped and lined with tons of small metallic panels on the interior. Our next source for this literature review from Lee et al. (2021) looks at one of the instruments scientists developed to get readings from inside one of these reactors. The authors describe an infrared bolometer protected by a thin foil they developed to measure ongoing reactions within a Tokamak reactor (Lee et al., 2021). As mentioned before, these reactors can run into thermal irregularities that cause an imbalance, and greatly decrease the efficiency of the fusion reaction. The bolometer the scientists developed is key to addressing these irregularities. The concept is that the instruments would be connected to a system that would use real time updates to intervene and mitigate thermal irregularities by injecting control materials during the reaction (Lee et al., 2021). The bolometer they developed was installed on the KSTAR Tokamak in 2020, and the results were validated in simulations and in experiments (Lee et al., 2021).
Our final source for this literature review from Jo et al. (2021) shifts gears again, and combines the science of fusion technology with the commercial practicality of its implementation. The researchers developed a method to measure the minimum radius of a Tokamak reactor for maximum energy output, at minimum cost (Jo et al., 2021). They concluded that the optimum design was a reactor that drives plasma by a “non-inductive external system,” with a minimum radius between six and seven meters (Jo et al., 2021). However, even at the most cost-effective point, such a reactor would cost between four and five billion USD.
My sources for this literature review were all very technical, and I did my best to summarize the key points. Much of the methodology for testing their hypotheses involved advanced physics and mathematics. However, I’m very satisfied with my choice in research topics, because the reading was all very insightful. In addition, I looked through hundreds of research papers, and I didn’t find any that represented the exact scope of the research I’m compiling. The articles seem to either be a brief introduction and very short analysis of fusion energy, or a highly technical analysis of specific subsystems.
III. Methodology
I structured my research around quantitative analyses within scientific journals concerning different aspects of fusion sciences, and around qualitative information from interviewing scientists in the field. I was able to find great literature to review for my quantitative analysis, and for my qualitative analysis, I conducted an interview with Dr. Alex Zylstra of The Lawrence Livermore National Laboratory. I aimed to find out, how do fusion energy reactors work? What are the risks, and what are the potential benefits? And finally, where does fusion energy generation currently stand as a means to supply the world with clean energy?
IV. Findings
i. How Do Fusion Reactors Work?
According to my research, the two leading technologies for fusion reactors are called Inertial Confinement and Magnetic Confinement. Both follow the same principle, which is to heat and compress materials until the atoms within the material are hot and dense enough to achieve fusion. The difference between them is the method in which they heat and compress the material. Inertial Confinement uses a series of extremely high-powered lasers to blast a fuel pellet from all angles in fractions of a second. Figure 1 shows the design of the reaction within an Inertial Confinement Reactor. Figure 2 is a picture of the Inertial Confinement Reactor at The Lawrence Livermore National Laboratory.
Inertial Confinement Reaction
Inertial Confinement Reactor
Magnetic confinement has a different approach, which is to use magnets to compress the fusion fuel to the density necessary for fusion to take place. Figure 3 illustrates the magnetic confinement process, and Figure 4 is a picture of the JET reactor at the Culham Centre for Fusion Energy.
Magnetic Confinement Reaction
Magnetic Confinement Reactor
ii. What Are The Potential Risks and Benefits?
When it comes to nuclear power, there is a long-lasting stigma on public opinion for accidents in the past. However, the processes of a fusion reactor differ greatly from a fission reactor. Fission reactors use nuclear fuel that needs to be cooled and moderated to prevent overheating. Additionally, generating nuclear waste is inherent to the process, as the fuel has a useful lifespan, and must be removed and stored safely upon its completion (Nuclear Waste, 2019). Fusion reactors can only produce reactions when systems are operating near peak efficiency. In the event that the systems are compromised, the reaction stops. In addition, fusion reactors burn away the nuclear fuel in the reaction process, so the technology is much cleaner than fission reactors. However, fusion reactors also have to replace structural components that are exposed to radiation, so they aren’t entirely free from generating nuclear waste.
iii. Where Does Fusion Energy Currently Stand As A Means To Supply The World With Clean Energy?
This was the primary question I aimed to find an answer for in my research. However, the answer isn’t what I had hoped for. With all the advancements taking place, I was hopeful that science was approaching the threshold of fusion reactors being a real possibility in the next decade. Unfortunately, that doesn’t appear to be the case. It’s possible that the technology could be validated within the next decade, but it’s also possible that it could be another five decades or longer. Scientists are able to create fusion reactions within the reactors I described earlier, but reactions still use more energy than they create. When a reactor is able to generate more than 100% of the initial input energy, then things can take a major step forward. However, even at that point, there are still limitations that will have to be overcome for fusion reactors to be commercially viable.
iv. An Interview with An Expert
Dr. Alex Zylstra is an incredibly accomplished physicist working at The National Ignition Facility within The Lawrence Livermore National Laboratory. It was very difficult to find a researcher to interview, and I’m extremely grateful for his participation. We met via the teleconferencing application WebEx, and discussed different aspects of fusion energy for about an hour on April 8th, 2022. To give a background into his work, he works with the reactor pictured in Figure 2, and was a part of the record-breaking team that achieved a 70% energy output in August of 2021 that I mentioned in the introduction (Rincon, 2021).
He described the challenge of fusion to be like squeezing a balloon. As it’s compressed from different sides, parts of the balloon like to poke out between the gaps. Stars use gravity to evenly compress materials from all sides, and reactors have a hard time matching such an even force distribution. However, the technology continues to improve, and I spoke with Dr. Zylstra about some of the improvements taking place.
A concept he said that contributed to the record-breaking experiment was the utilization of “self-heating” (A. Zylstra, personal communication, April 8, 2022). This is when the heat from the initial fusion reaction is used to continue the reaction throughout the remaining materials. This makes the reaction more efficient, as the reactor can utilize existing energy within the reaction. He also spoke about the fusion materials within capsules called “targets” (illustrated in Figure 1) and described how developments within the design of “targets” were also responsible for the record-breaking experiment (A. Zylstra, personal communication, April 8, 2022).
I asked Dr. Zylstra about which technology he thought had the best prospect of generating electricity, between Inertial Confinement and Magnetic Confinement, and he said the discussion is “premature” (A. Zylstra, personal communication, April 8, 2022). Both technologies have advantages, but it’s too soon to “put all of our eggs in one basket” (A. Zylstra, personal communication, April 8, 2022).
V. Discussion
I started my research with very little prior knowledge of fusion energy. My initial intention was to frame the research within the context of other energy sources. However, as I learned in the process, the technology is still too underdeveloped to make valid comparisons to other energy sources. It will be a while before reactors are actually able to output electricity, so any comparison to other energy sources would be speculation.
The literature I reviewed provided insight into some of the developments within fusion and plasma sciences. The studies played a part in my ideology, but my research was geared toward a more general overview of fusion reactors as a whole, instead of focusing on specific aspects of fusion sciences. My findings connect the dots for what fusion energy is, and where it stands currently as an option for a source of electrical power. Using what I’ve learned, if I were to continue my research, I’d focus on the problems standing in the way of fusion energy being commercially viable. Costs are a factor, but from what I’ve gathered, the largest inhibitors are from materials and from the reaction process itself. From producing fusion fuel, to maintaining the reactor’s interior components that are exposed to extreme conditions, material management is currently a major limiting factor. Additionally, producing fusion reactions is inexplicably complicated, and that is where the focus is currently: to figure out the best and most efficient way to produce reactions. The discussion of generating electricity will only be practical once the science of producing efficient fusion reactions has been sufficiently validated.
VI. Conclusion
Fusion reactors are on the cutting edge of science, and many scientific breakthroughs are happening within the field. My goal for my research was to see where the technology is now in 2022, and I feel like I’ve accomplished that goal. I’ve learned what fusion reactors are and how they work. I found out more about the risks and benefits involved with the technology. Finally, I was able to see where the fusion energy currently stands as a means to supply the world with clean energy. Despite how far the technology still has to go, and how difficult and uncertain the development process is, I’m still hopeful that fusion energy will be a commercial reality in the future. However, only time will tell how far into the future that is.
References
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EUROfusion. Magnetic Confinement Reaction. https://www.energy.gov/science/doe-explainstokamaks
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Jo, G., Jae-Min, K., Cho, A., Hyun-Kyung Chung, & Hong, B. (2021). Cost assessment of a tokamak fusion reactor with an inventive method for optimum build determination. Energies, 14(20), 6817. http://dx.doi.org/10.3390/en14206817
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Lee, M. U., Thatipamula, S. G., Sehyun, B., Jayhyun, K., Kim, J., Lehnen, M., & Yun, G. S. (2021). Radiation measurement in plasma disruption by thin-foil infrared bolometer. Review of Scientific Instruments, 92(5), 053536. http://dx.doi.org/10.1063/5.0043859
Los Alamos National Laboratory. Inertial Confinement Reaction. https://www.lanl.gov/projects/dense-plasma-theory/background/dense-laboratory-plasmas.php
Nuclear Waste. (2019, November 22). Nuclear Energy Institute. Retrieved April 9, 2022, from https://www.nei.org/fundamentals/nuclear-waste
Phillip Saltonstall/Lawrence Livermore National Laboratory. Inertial Confinement Reactor. https://www.nbcnews.com/sciencemain/fusion-energy-dreams-smash-hard-economic-realities-6c10442409
Rincon, P. (2021, August 17). US lab stands on threshold of key nuclear fusion goal. BBC News. Retrieved April 4, 2022, from https://www.bbc.com/news/science-environment-58252784
Rinderknecht, H. G., Wang, T., Garcia, A. L., Bruhaug, G., Wei, M. S., Quevedo, H. J., . . . Arefiev, A. (2021). Relativistically transparent magnetic filaments: Scaling laws, initial results and prospects for strong-field QED studies. New Journal of Physics, 23(9), 095009. http://dx.doi.org/10.1088/1367-2630/ac22e7