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| Fig. 1: Location of the planned ITER tokamak fusion plant in southern France. (Source: Wikimedia Commons) |
It should not come as much surprise to hear that the world must look for new forms of electricity. The recent United Nations IPCC report suggests that the world may only have a matter of decades to curb its fossil fuel addiction before we face irreversible consequences. Much talk about how to go about this involves a combination of carbon sequestration, and a dramatic increase in renewable energy. Generally, the main renewables mentioned are Wind, Solar, Hydropower, and Nuclear. This article seeks to look at the latter action, but not in the way one normally would at first glance.
Nuclear energy is typically associated with nuclear fission plants, which work to boil water to make steam, that then turns a turbine, leaving in its wake a prodigious amount of nuclear waste needing disposal. To fission's credit, the process to create energy through it has been made quite simple by scientists.
There is another type of nuclear power, however, that could hypothetically produce as much power with a glass of seawater as one currently can by burning a barrel of oil. This is through nuclear fusion, a process through which the sun and all other stars create energy. It seems quite reasonable to think creating a de facto star on earth could solve much of the global energy crisis. [1] Fusion can actually be explained simply: if you heat up atoms millions of degrees, they will be stripped down to plasma. Even though the now-abundant nuclei are all positive and should repel each other, if they are moving fast enough (through heat or pressure), they will merge together into a heavier nucleus. The energy created in this process is self sustaining and huge in amount; clearly the law of conservation of mass infers energy out is same as energy in, but fusion moves much of this energy from the multiple small nuclei pre-fusion to usable energy. [2]
Unfortunately, humans have not yet been able to recover a slow, sustaining energy net production gain from such reactions. While Hydrogen Bombs show the ability to collide atoms and create prodigous energy, fusion plants are striving to have nuclei collide in a way that will continue the controlled reaction. Nonetheless, due to the readily available elements needed for nuclear fusion, if the technology can get to the point where scientists get our more energy than they put in, then earth may just have solved its energy crisis for good. [3]
There are still many unsolved problems inhibiting workable fusion. For magnetic fusion reactors, such as the ongoing ITER project in France, the world still needs a proper heat exhaustion system (a diverter), fusion materials which are neutron-resistant, and ways to produce more of the all important tritium element. [4] Building such a diverter is of specific interest for tokamak type reactors, such as the massive ITER reactor. In addition to taking care of plasma heat, diverters are also needed to process the byproduct of helium ash. Further, the diverter must be integrated to be able to intake such a massive heat load of 10 MW/m2 over a long period of time in addition to prodigious neutron loads. ITER will be massive in size-- the biggest fusion plant built to date-- in order to prevent heat loss from the walls during the reaction. [4]
Unfortunately, though we have a large amount of deuterium - one of the two main elements in fusion reactions which is quite stable - its reaction partner tritium is radioactive and is found in lesser quantities; thus a new reaction "second element" may be needed. Surprisingly, once we begin to eliminate certain isotopes, there are not too many ideal candidates to add to this reaction. [5] A final experiment of ITER will be to test tritium breeding, as another way to make the compounds needed for the reaction more available. [6]
The premise of nuclear fusion is quite intriguing. In the coming years, we will see the largest fusion experiment in the world completed in France: ITER. Funded and worked on by a multi-country coalition, this plant will attempt fusion through a magnetic confinement reactor. As can be seen in Fig. 1, ITER is located in France, highlighting that the European Union is contributing some 45% of the cost for the reactor. ITER has a goal of dramatically changing the results of fusion reactions from our current inability to create energy from such reactions to a 10× energy gain (q=10). [7]
Meanwhile, the the National Ignition Facility in the US continues attempts at Inertial Confinement.
There is clearly a risk at fusion now: it can be viewed almost as a current luxury to the other, ready to roll out renewables. Why not fully fund deployment of solar panels and wind turbines, try to avert climate change, and then focus on fusion? Perhaps, because the allure of a naturally sustaining energy source is too strong.
© Eli Wachs. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] N. Armaroli and V. Balzani, "The Future of Energy Supply: Challenges and Opportunities," Angew. Chem. Int. Ed. 46, 52 (2007).
[2] E. Margaret Burbidge et al., "Synthesis of the Elements in Stars," Rev. Mod. Phys. 29, 547 (1957).
[3] A. J. H. Donné et al., "Scientific and Technical Challenges on the Road Towards Fusion Electricity," J. Instrum. 12, C10008 (2017).
[4] J. H. You et al., "Conceptual Design Studies for the European DEMO Divertor: Rationale and First Results," Fusion Eng. Des. 109, 1598 (2016).
[5] D. Stork and S. J. Zinkle, "Introduction to the Special Issue on the Technical Status of Materials for a Fusion Reactor," Nucl. Fusion 57, 092001 (2017).
[6] J. Chabolla, "International Thermonuclear Experimental Reactor (ITER)," Physics 241, Stanford University, Winter 2017.
[7] L. Zabeo et al., "Overview of Magnetic Control in ITER," Fusion Eng. Des. 89, 553 (2014).
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