Thought Leader BERT OLIVIER November 30, 2015
Lev Grossman (“Star Power”, in Time, November 2, p. 24-33) calls fusion the “holy grail” of “the quest for clean energy”, and with good reason — it is as elusive as the proverbial unicorn in your garden (with apologies to James Thurber). By this I mean that, although scientists and technologists know what has to be done to actualise it as a source of energy, it seems virtually impossible to do so. At least until now. Grossman is of the opinion that, this time, it might actually work. This is what he has to say about “the machine” he visited (p. 26):
“The machine is a prototype fusion reactor. It is the sole product of a small, secretive company called Tri Alpha Energy, and when it or one like it is up and running, it will transform the world as completely as any technology in the past century. This will happen sooner than you think.”
He further informs that this is one of a few dozen fusion reactors located in different places around the world, all of them at different stages of development. The largest one is in the south of France, and bears the imposing name of the International Thermonuclear Experimental Reactor. It will cost about $20 billion and is scheduled for completion in 2027. Moreover, fusion research that feeds into the construction of such reactors is accompanied by “a lot of hype and not much in the way of actual fusion” (p. 26). This is what people have come to expect, because (hitherto futile) attempts to produce energy via fusion go back to the 1940s.
But what is nuclear fusion, and why is it worth pursuing the goal of building a functioning fusion reactor if it has consistently eluded humanity? One has to appreciate the differences between nuclear fusion and nuclear fission to grasp what is at stake here. Fission is the process of splitting the nucleus of atoms into smaller components. As is fairly well-known, when this is done, colossal quantities of energy are produced, but at the cost of simultaneously releasing huge amounts of lethal radiation. Fission occurs when atom bombs are detonated and also in the process of generating energy in the form of electricity in nuclear power stations. The risks and dangers accompanying it are (or should) also (be) well-known.
Fusion, by contrast, does not entail the division of atoms, but the unification or merging of the nuclei of atoms, a process that occurs in stars, including our sun. Not surprisingly, therefore, it requires immense heat and pressure. Grossman puts it like this (p. 26-28):
“Nuclear fusion is the reverse of nuclear fission: instead of splitting atoms, you’re squashing small ones together to form bigger ones. This releases a huge burst of power too, as a fraction of the mass of the particles involved gets converted into energy (in obedience to Einstein’s famous E=mc squared). Fusion has a vaguely science-fictional reputation, but in fact we watch it happen every day: it’s what makes the sun shine. The sun is a titanic fusion reactor, constantly smooshing hydrogen nuclei together and sending us the by-product in the form of sunlight.
“As an energy source, fusion is so perfect, it could have been made up by a child. It produces three to four times as much power as nuclear fission. Its fuel isn’t toxic, or fossil, or even particularly rare: fusion runs on common elements like hydrogen, which is in fact the most plentiful element in the universe. If something goes wrong, fusion reactors don’t melt down; they just stop. They produce little to no radio-active waste. They also produce no pollution: the by-product of fusion is helium, which we can use to inflate the balloons for the massive party we’re going to have if it ever works.”
One might wonder why, if humans have been able to create the technical conditions for nuclear fission to occur, their technological prowess has not yielded the construction of technical devices that would produce fusion. Earlier I mentioned extreme heat and pressure. Just how extreme they have to be becomes apparent when one tries to imagine conditions at the core of the sun, which has a mass 330 000 times that of the earth. These conditions have to be re-created on Earth for fusion to happen, and this means that the unimaginable pressure produced by the sun’s mass at its core, as well as the accompanying temperature — 17 million degrees Celsius — has to be reproduced in the fusion reactors humans are trying to construct. It is even more difficult on Earth, however: because the quantities of fuel here are so much smaller than on the sun, fusion only becomes practicable at temperatures of approximately 100 million degrees Celsius.
Boggles the mind, doesn’t it? It gets even more so when one reads that the positively charged atomic nuclei, consisting of protons and (usually) neutrons are excessively difficult to force together (like magnets with the same charge); hence the pressure and heat required. When the temperature and pressure are adequate to the task (like in the heart of the sun or a star), they become what is called “plasma” — a bizarre “cloud of free-range electrons and naked nuclei” (p. 8), and under these conditions some nuclei collide with sufficient force to merge, or “fuse”.
If this could be technically achieved on Earth it does not mean that one’s problems are over, though. The plasma, when produced, behaves in “weird” ways. Grossman writes that it is a “fourth state of matter, neither liquid nor solid nor gas” (p. 28), which turns completely unstable under the required conditions. Hence the problem: one has to contain it, and control it without making contact with it, lest any solid matter be immediately turned into vapour.
Two methods that have been used to create fusion are by means of powerful laser beams fired at hydrogen (producing 500 trillion watts at a time — a thousand times more power than used by the whole of the US at any time), and through the use of electromagnetic fields to confine and compress plasma without actually touching it. This is done in a “tokamak” — a device invented in the Soviet Union around the 1950s, and gigantic ones of which were built in Japan, the US and Britain at enormous cost in the 1980s. The fusion reactor referred to earlier, which is under construction in France, is the mother of all tokamaks, and it is hoped that it (or another one of those being built today) will succeed where the others failed, although some big tokamaks apparently “came close” (p. 29) during the 1990s. But even if it succeeds, it won’t be supplying power for use by consumers because, despite its enormous projected cost (more than four times what the Large Hadron Collider cost) it is fundamentally a “science experiment” (p. 29) aimed at examining the viability of nuclear fusion.
So why is so much money and technical effort spent on building fusion reactors? Grossman sums it up in one sentence (p. 29): “The real world needs clean power and lots of it.” Furthermore, it is safe because, unlike fission, it does not involve a “chain reaction”, radiation levels are negligible and even if the extremely hot plasma somehow leaked out of the reactor, “its heat would dissipate rapidly and harmlessly into the atmosphere” (p. 31). (Adding to global warming?)
What should one think of this? If it is as safe as everyone who is in the know seems to think it is, I guess it would be a far better option than the high-risk nuclear power from fission that already exists all over the world in the shape of nuclear power stations, including in South Africa. Time’s cover proclaims that fusion would entail “Unlimited energy. For everyone. Forever”. A very large claim. And some people — like Michel Laberge, founder of the company General Fusion (p. 31) — believe that the time-line is as short as a decade.