Fusion Energy Is Still A Decade Away—At Least

 

Last December 5, at 1:03 AM in California's National Ignition Facility, 192 lasers fired into a tiny metal can called a "hohlraum" which contained a peppercorn-size fuel pellet consisting of frozen deuterium and tritium.  In response, some of the atoms in the pellet fused and released more energy than it took (in the form of laser beams) to start the reaction. 

 

At a news conference afterwards, U. S. Secretary of Energy Jennifer Granholm called the experiment a "fusion breakthrough" and the hundreds of scientists who have labored for years to achieve what is technically called "ignition" were thrilled to learn that they had finally achieved a goal they had worked toward for decades.

 

They indeed deserve congratulations, because they are the first group in the world to demonstrate ignition with their type of fusion reactor, which is termed inertial confinement.  At the same time, it's a little premature to sell all your fossil-fuel stocks and order your Back to the Future fusion-energy car that runs on a glass of water.

 

Inertial-confinement fusion is one of those simple-sounding ideas that turns out to be fiendishly complicated in practice.  Not long after the laser was invented (1960), it occurred to somebody that the short intense burst of energy that certain pulsed lasers could make might be able to heat up deuterium and tritium enough to cause their nuclei to fuse, leading to a fusion reaction.  Nuclear fusion has been the pot of gold at the end of the energy rainbow ever since fusion was demonstrated in the first thermonuclear hydrogen bomb test called Ivy Mike in 1952. 

 

The device that made the nuclei fuse in that explosion was a conventional nuclear-fission bomb, of the type dropped on Japan at the end of World War II.  So far, bombs are the only reliable way to get a lot of energy out of nuclear fusion, but they are hardly a practical energy source.

 

Fusion is an attractive source of energy because the raw material—deuterium, mainly—can be extracted from ordinary water, the energy output per weight of fuel is even better than fission reactors, and the waste products tend to be less nasty than those from fission reactors, which is the only way we get practical amounts of energy from nuclear reactions these days.  Most efforts in making fusion practical try to work with ways of containing a hot ionized gas called a plasma inside various tricky confinement chambers in a continuous process that would put out a steady flow of energy.

 

But confining a plasma is a little bit like nailing Jell-O (TM) to the wall:  it doesn't want to stay put.  So in 1994, the National Ignition Facility (NIF) began to study ways of doing it in a batch process, rather than continuously.

 

Rather than having to keep the plasma confined constantly, their idea was to shoot a whole lot of laser-beam energy onto a small pellet of fuel, that would then get so hot part of it would fuse, and the burst of fusion energy coming out would be larger than the energy it took to make it.  In the meantime, it would be confined by its own inertia—hence the name "inertial confinement."

 

It sounds simple, but the NIF people have been working for nearly thirty years to do the thing that their lab is named for—namely, achieve ignition.  So at last, in December the lab lived up to its name.

 

Are we home free?  Not yet.  For one thing, the amounts of absolute energy we are talking about are trivially small.  Two megajoules of laser-beam energy went into the pellet and produced fusion energy of three megajoules.  A megajoule sounds like a lot until you realize that three megajoules of energy is contained in about a fourth of a measuring cup (100 ml) of gasoline.  So the process will have to be scaled up seriously before practical amounts of energy are produced.

 

Also, the lasers are not 100% efficient.  One scientist at the news conference admitted it took "well over 400 megajoules" to charge the lasers that created the 2-megajoule beam.  That reminds me of the guy who went into business and admitted he was losing money on each transaction, but he'd make it up in volume.  Sometimes you can do that, but sometimes you can't.

 

So while the NIF folks deserve congratulations for their achievement, one wonders if inertial confinement fusion for practical energy generation will ever see the light of day.  It begins to look like one of those things that would work given indefinite amounts of resources, but at some point, other researchers will overtake it and further work will be pointless.

 

I was once engaged in an engineering project that lost my company six million dollars.  Some years later, I ran into the manager I worked for, who said about it, "Well, if we'd just had a little more time and money, I think we could have made it work."  Yes, but we didn't, and it was a good thing for the company that we stopped.

 

A huge project based in France called ITER is pursuing a different approach: a giant "tokamak" style continuous-plasma reactor that is scheduled to make its first plasma (of any kind) in 2025.  From what I can tell, ITER's main use so far has been as a way to employ thousands of European physicists, engineers, and auxiliary personnel.  But it may turn out to work. 

 

Personally, I hope all these behemoth-like government-funded decades-long projects are shown up by one of the dozens of small startup fusion companies that are pursuing off-the-wall fusion ideas, ranging from boron fusion (with hardly any dangerous waste products) to modifications of a thing called a "fusor" developed by Philo T. Farnsworth, the guy who didn't invent television.  Actually, he did invent an alternative approach to the TV camera tube that was not as good as the one RCA and its Vladimir Zworykin came up with, but Farnsworth was an independent inventor and RCA was tied in with the government and dominated the entire radio-electronics sector.  Sometimes the big guys win and the little guys lose, but not all the time. 

 

Chances are that I will no longer be around to see the first commercial electric power delivered from fusion energy.  But if it ever happens, I hope somebody like Philo Farnsworth invents it.

 

Sources:  USA Today carried a report on the NIF breakthrough on Dec. 13, 2022 at https://www.usatoday.com/story/news/nation/2022/12/13/fusion-energy-advance-clean-power/10883067002/.  The energy content of gasoline was from https://www.engineeringtoolbox.com/fossil-fuels-energy-content-d_1298.html and I also consulted Wikipedia's articles on the National Ignition Facility and ITER.

Will Fusion Energy Always Be Forty Years In the Future?

 

Indulge me in a little stroll down Nerd's Memory Lane.

 

When I was in high school, I heard about an upcoming talk on nuclear fusion that was going to be part of some publicity event in a new Fort Worth theater.  As my grandmother was the theater director's secretary, that may be how I found out about it.  Anyway, I went.

 

It was a good crowd, and the guy presenting the talk described what nuclear fusion was in layman's terms, talked about what had been tried so far, and went into considerable detail.  This was probably around 1970, mind you.  Hydrogen bombs (more exactly, thermonuclear weapons) which are still the only way we know how to produce a large amount of energy with fusion, were less than twenty years old.  The speaker may have mentioned tokamaks and plasmas and so on, and while I was listening I thought of a question to ask him at the end.

 

There were several people lined up before me, and the guy, who looked plenty old enough to me to be an Authority (although he was probably only about 40), patiently answered all the questions people had, even stupid ones.  I was the last person in line.  I asked him if somebody had thought of using feedback control to stabilize plasmas, and he said yes, that was one thing they were considering.  I felt thrilled to have thought of something that would almost certainly become an important source of energy by the time I was his age, or a little older.

 

Well, fast-forward fifty-one years or so.  No one has yet put a single watt-second of fusion energy into a power grid anywhere.  On the website of the electrical engineering profession's general-interest magazine IEEE Spectrum, there is an interview with a professor of science journalism named Charles Seife who thinks the latest "milestone" announcement by the U. S. National Ignition Facility (NIF) is not so much a milestone as they claim it is.  More like so many minutes on a treadmill, perhaps.

 

What the NIF announced was that they managed to ignite a lump of fusion fuel to the extent that it made 1.3 megajoules of energy.  Just to put that in perspective, that's about the energy content of a pound (0.45 kg) of gunpowder.  I don't know how many billions of dollars has been spent on the NIF, but if that's all they can do with it so far, it'd be a lot cheaper to wait till New Year's and buy a lot of firecrackers.

 

Not to be too cynical, Seife admits there is a legitimate reason to keep the NIF running, but he thinks it has little or nothing to do with the practical goal of fusion energy.  The NIF was founded to study nuclear weapons, because the same basic process is used both in thermonuclear weapons and other types of fusion processes.  As long as we in the U. S. wish to remain members of the nuclear-weapon club, we need to keep our thermonuclear powder dry, so to speak, which means maintaining experts that know how to make sure the bombs will go off when we want them to, and not otherwise.  So letting them fool around with stuff like the NIF keeps them occupied and in practice for checking nuclear weapons without actually setting them off above ground, which is forbidden by the Nuclear Test Ban Treaty.  Technically, we can test them underground, but because seismological instruments can tell almost anybody nearly as much about the test as we could find out ourselves, that's not done a whole lot either—the last U. S. underground nuclear test was in 1992. 

 

However, selling the public on keeping nuclear-weapons scientists in fighting trim is a hard job, while promising them electricity "too cheap to meter"—a famous catch-phrase of early proponents of fusion power—is a lot easier.  The elephant in the fusion lounge is ITER, the International Thermonuclear Experimental Reactor, a multinational collaboration based in France which has been keeping lots of mainly European scientists and engineers busy since 1979, or only a few years after my conversation with the fusion evangelist.  ITER's latest deadline to first make plasma is 2025, although they have had considerable schedule slippage over the years.  And who knows how far it will be between making plasma (which any neon sign does whenever you turn it on) and making money by selling electricity made from fusion energy?

 

From an ethical point of view, the main issue I see here is how scientists present their work to the public.  Some things are inherently easier to sell in some cultures than others.  For some reason which may have to do with the displacement of faith in God by faith in the Universe or science, U. S. astronomers are able to extract some $30 billion a year from the federal government, roughly speaking (this includes all of NASA's budget and the NSF budget for astronomy-related activities).  In a day when Congress tosses trillions around like popcorn, that doesn't sound like much.  But for an activity which explicitly excludes profit motives—who ever made money off the Andromeda Galaxy?—that's a good chunk of change.  By and large, the public agrees with astronomers that what they do is cool, and pays for it.

 

Maybe the NIF people need to jazz up the coolness of what they're doing.  I've seen photos of a similar facility, the Z-machine at Sandia Labs, which outdoes anything in Frankenstein's lab for impressiveness.  Of course, just saying you do cool things with sparks or lasers will only take you so far.  But it might be worth a try, rather than setting up goalposts that promise more than they deliver.

 

Sources:  The interview with Charles Seife is at https://spectrum.ieee.org/has-fusion-really-had-its-wright-brothers-moment.  The energy comparison with gunpowder is from https://chesterenergyandpolicy.com/2017/12/27/the-hidden-energy-of-new-years-even-celebrations-measured-in-joules/#:~:text=While%20most%20real%20firecrackers%20are,48%20J%20of%20explosive%20energy and the date of the last U. S. underground nuclear test is from https://allthingsnuclear.org/emacdonald/is-the-united-states-planning-to-resume-nuclear-testing/.  A photo of the z-machine in operation is at https://www.sandia.gov/z-machine/.