Saturday, March 01, 2014
Will The Fusion Sun Ever Rise?
Back when I was in high school almost fifty years ago, I attended a talk about fusion power. The speaker explained how fusion reactors worked differently than fission reactors, and used only water as fuel instead of highly radioactive uranium or plutonium. He spent a good bit of time on the difficulties standing in the way of commercial power generation with nuclear fusion reactors, and dwelled on how hard it was to keep a thin, extremely hot gas (plasma, really) from wriggling around and extinguishing itself on the chamber walls. After his talk, I waited in line to ask him a question that had occurred to me: whether you could apply feedback of some kind to stabilize the plasma? He kindly told me that my idea was one of many "under consideration," and I went away with the sense that I could participate in a great human achievement in the future: the harnessing of fusion energy for peaceful purposes. I don't recall exact figures, but I believe the speaker said that he hoped fusion power would become a practical reality in ten or twenty years.
Well, it's nearly half a century later, and nearly a century after British physicist Sir Arthur Stanley Eddington realized that smashing hydrogen nuclei together to make helium would yield an astonishing amount of energy. My career led me in other directions than fusion research, and perhaps it's just as well, because fusion power is still like the glow that appears before the sunrise: promising, but not delivering yet. While there have been dozens of projects big and small (considering the scale of this type of research, I should say "big and bigger") in the intervening years, the frontrunner these days is an international collaboration called ITER.
ITER stands for "International Thermonuclear Experimental Reactor" and is also Latin for "the way," as in "iterate." Although the machine itself is to be built in France, its finished components come from South Korea, Russia, India, Japan, China, the U. S., and other European nations as well. The project has been going in some form or other since the 1990s, and so far about 15 billion euros (almost $21 billion US) have been spent. The project's managers estimate it will be another six or seven years before they can flip the switch and expect anything good to happen, and another seven years or so before the unit could be used for commercial power generation. That gets us to 2027. If I'm still around then, I'll be 74.
Why have so many people spent so much time and effort on an idea that seems determined not to be born? Its attraction is captured in a slogan that was popular in the early days of the promotion of fusion energy: "too cheap to meter." This phrase was originated in the days when the fuel cost of energy was the main concern, and fossil fuels were relatively expensive compared to water. The deuterium in water, plus perhaps some lithium, which is not as cheap as it used to be but is still relatively abundant, are the only fuels needed for the type of thermonuclear fusion that is under development at ITER. Ten thousand gallons of water, which would fit comfortably in a cube 12 feet (4 meters) on a side, contains about a gallon and a half of heavy water, the kind that contains deuterium. I calculate that this much deuterium could provide enough electricity to run a thousand average households for over three years.
Another advantage advertised for fusion is that it produces much less radioactive waste than nuclear fission reactors do. Fission reactors are the kind we currently use for electric power generation commercially. Fusion makes no long-lasting radioisotopes to bury for ten thousand years or otherwise dispose of inconveniently. And the risk of meltdown or a violent explosion is practically nil. It's taken the physicists eighty years to get close to getting it to run, and so you take away one little adjustment from the complex of conditions needed to operate the thing, and it just flashes and dies harmlessly.
With all these attractions, it's understandable that hordes of physicists and their funding sources have poured decades of effort and resources into the search for "ignition," which is their term for getting more energy out of the reaction than you put in. If all you want is ignition and don't care about controlling it, that's easy—just steal a thermonuclear bomb, which has been around in one form or another since 1952. It's the control part of the problem that has kept the promise of peaceful thermonuclear energy just out of reach for all these years.
I hate to be a spoilsport, but what if the complexity and maintenance of a commercial-grade fusion reactor is so high that, despite all the international efforts, the thing simply doesn't ever manage to pay for itself? After all, paying the bills is the test of an engineering idea, and whatever the physicists say, the pursuit of fusion power has been as much an engineering effort as a physics effort. The basic physics was figured out by 1950 or so—everything since then has been practical details. Already, the ITER project is giving off bad signs of disregard for costs. Currently, according to a recent report in the New Yorker, the project managers have no accurate estimate of how much it will cost to finish. The thing is beginning to resemble the United Nations organization, and not in a good way. It is becoming increasingly hard to imagine how a technology with such a scary financial record will ever be considered seriously by those who actually expect to make money from an investment before dying, even after the technical achievement of ignition has been accomplished.
The crystal ball is always cloudy, but wouldn't it be ironic if, just when ignition is achieved and the physicists at ITER break out the champagne, the rest of the world greets them not with a cheer but with a yawn? "You mean we have to build more power lines across our back yards to use that so-called free energy? You mean we have to pay X billion euros to retire the bonds it took to build this thing? No, thanks." As the curve of complexity and expense it takes to achieve nuclear fusion has been going up, the curve of what the world will tolerate in terms of a new major source of electricity has been going down. For the sake of all those who have dedicated their professional lives to the cause of commercial nuclear fusion power, I hope that when and if we get it, we'll really want it enough to pay for it.
Sources: Although I had not finished reading the article before this blog was completed, the part of Raffi Khatchadourian's article "A Star In A Bottle" in the Mar. 3, 2014 issue of The New Yorker that I read was very informative. I also referred to Wikipedia articles on thermonuclear fusion, thermonuclear weapons, ITER, Arthur Eddington, nuclear fusion, and fusion energy. The website by C. R. Nave at Georgia State University has a good summary of the basic fusion reactions used in fusion energy at