Fusion Power: The Joke of Science or Energy Panacea?
Illustration by MIT SPARC team August 11, 2015
When you think of nuclear power, what comes to mind? Radiation logos? Maybe news of a massive meltdown? Yet what if I told you that nuclear power has more to offer, that it is not only an effective energy source but also the key to solving the world’s energy and climate crises? In that case, welcome to the world of fusion power.
But first, some history is in order. In 1926, Arthur Eddington, in his paper The Internal Combustion of the Stars, determined that stars power themselves by fusing hydrogen atoms into helium atoms, and so Eddington discovered the process in physics that we now call fusion. When in 1942, Enrico Fermi and his team built the Chicago Pile 1, the world’s first functioning fission (when atoms split apart in a chain reaction) based nuclear reactor, physicists could not help but wonder if a nuclear reactor could be built using fusion instead of fission. By 1951, physicists no longer had to wonder, with Department of Energy funding in hand, it was time to turn fusion power into a reality.
If you know nothing about developments in fusion reactor technology, you are far from alone.“Fusion research has been on the scientific backburner for some time now, and so the public is ignorant of developments in this field”, says Richard Ibekwe, a Nuclear Engineer and researcher at the MIT Plasma Science and Fusion Center(PSFC). He explains, “It makes sense that the public knows little about fusion; though we have made significant progress, we still lack a working reactor”. The lack of a working reactor after 70 years of research, says Ibekwe, shows the herculean endeavor of building a working reactor. This is why the recent rare breakthroughs in fusion research should have us sitting at the edge of our seats.
In September 2021, Commonwealth Fusion Systems(CFS), a private partner with MIT’s PSFC, began building the SPARC fusion reactor. As Richard Ibekwe explains, “the physics needed to make a viable fusion reactor has existed since the 1940s, but SPARC is the first time the technology is available to make such a device”. Incorporating artificial intelligence and parallel processing to efficiently map out particle collisions within the plasma in the reactor and utilizing advances in materials science such as the discovery of REBCO, or rare-earth barium copper oxide, a key superconducting material needed to produce the electromagnetic fields necessary to keep the superheated plasma in the reactor from touching the reactor walls, SPARC is the closest humanity has ever come to producing a fusion reaction that generates net energy.
With bachelor’s degrees in mechanical and nuclear engineering and a Ph.D. in Nuclear engineering all from MIT, Richard Ibekwe conducts research into superconductors and magnets for fusion reactors. His work on SPARC centers on how to lower the threshold of electricity needed to induce a fusion reaction. In finding rare-earth barium copper oxide (along with a team of course), he has made a breakthrough. “REBCO is a game-changer because it allows us to superheat plasma (an electrically charged gas), which is required to fuse hydrogen atoms together, with far less electricity”, says Ibekwe.
Meeting Lawson’s criteria is the main roadblock to constructing a viable fusion reactor. Lawson’s criteria has three parts. One, plasma must be confined at a sufficient temperature, two, plasma must be confined at sufficient pressure, and three, plasma must be confined for a sufficient time in order for a fusion reaction to occur. Meeting criterion number one is the most difficult. When researchers make the temperature inside the plasma hot enough to meet the Lawson criterion, the heat melts the reactor walls. Melting is avoided by magnetically suspending the plasma, but this too is difficult.
As you can imagine, massive magnetic fields are required. The only way to induce such a magnetic field is through a significant amount of electricity, on the order of gigawatts. By working with superconductors (materials that do not have resistance and thus conduct electricity with zero power loss) like REBCO, the PSFC team has been able to drastically shrink the amount of input energy needed to generate a fusion reaction by an order of 10³, so only megawatts are now required. Soon enough, only kilowatts will be required to meet Lawson’s criteria.
The SPARC project, having just cracked the heating problem using REBCO technology, is now in the construction phase, and should be finished by 2025. But SPARC is not the end goal of the research of the PSFC, ARC is.
For the PSFC and Nuclear engineers, ARC does not refer to geometry as in a portion of a curve, or architecture as in the arc de Triomphe, but instead is an acronym which means “Affordable, Robust, Compact”, ideal qualities of a fusion reactor. “The goal of the ARC project is to put SPARC technology on a commercial and compact scale” cites Ibekwe. Essentially, SPARC proves that fusion reactors can work, while ARC makes sure they power our world. Currently, the SPARC reactor is 3 times as large and 6 times as expensive as ARC is supposed to be by 2030 according to estimates by MIT PSFC.
A CAD rendering of the PSFC ARC fusion reactor. Illustration by MIT ARC team October 16, 2020
Producing a working fusion reactor has significant implications for the future of alternative energy. “Solar, wind, geothermal, all of these alternative energies are great, but if we crack fusion, there is no contest anymore”, says Ibekwe. “Fusion power can produce so much energy, who knows the sorts of technologies that we can come up with once we have a working reactor”. Thus, producing a fusion reactor is more than just pushing the limits of engineering and physics, it is about unlocking a power that could alter humanity’s course in the fight against climate change. “There is this joke about fusion among scientists”, Ibekwe quips, “that it is always 30 years away”, “with SPARC and ARC, I think by the 2030s, I think we can put that joke to rest”. Let’s hope that’s the case.
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