UPDATE 12/27/22: the promising headlines about fusion persist. Meanwhile I’ve been collecting headlines. This Quora post does a great job educating why terrestrial fusion is not happening. Tl;dr the fusion reaction they’re talking about needs tritium, which requires a fission breeder reactor to produce. That fission reaction produces way more energy than the ensuing fusion reaction.
Anyway, on to the main post.
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With global warming becoming a hot topic again (so to speak,) the discussion on alternatives to fossil fuels to power our society is back. And once again, Nuclear Fusion is presenting itself as an enticing utopian fix. Nuclear fusion differs from our conventional fusion reactors in that it creates no radioactive waste products – only helium. And its fuel? Using the hydrogen found in water, a couple gallons of water could in theory power an entire city for a day.
The basic science is simple – fuse two hydrogen nuclei together to make helium and release a ton of energy in the process. The issue is in the application – the only way we know how to do this is through pressure and heat, the kind found in the center of the sun or a nuclear bomb explosion. Creating these conditions in a stable contained reaction has kept it a mirage that has led to misleading claims, time after time. However, because global warming modernly occupies a place of primacy in the news, claims of solving the worlds energy crisis with nuclear fusion are back. Media is rife with claims that we are on the brink of perfecting this clean source of energy, a mere 5-7 years away.
There’s nothing new about these new claims. No new science, no breakthrough developments. I’m going to try to dispel some lingering misnomers, myths and legends relating to Nuclear Fusion.
Fission and Fusion
Fission and fusion are both nuclear reactions, which are totally different from chemical reactions. Fossil fuels release energy through chemical reactions: carbon and hydrogen combine with oxygen from the atmosphere and become carbon dioxide and water. But the carbon and hydrogen in the fuel remain the same elements.
Nuclear reactions release energy from the nucleus of the atom, changing it into a completely different atom. It’s a totally different process and we don’t quite understand the internal workings of it. We just know the conditions under which it happens.
There are two types of nuclear reactions: fission and fusion. Fission is when we get very heavy elements – heavy metals like uranium or plutonium – and cause them to split into lighter elements like lead. We first perfected this process with the atom bomb, and then in nuclear power reactors. It’s a relatively simple process because heavy elements are rather unstable. A split atom releases energy and neutrons, which hit other elements and cause them to split – what we call a chain reaction. We can regulate this chain reaction to be as wild (bomb) or controlled (power) as we want.
Fusion is when we combine two of our lightest element – hydrogen – together into helium. This is a completely different reaction, that doesn’t have the same capacity for chain reaction as fission. The only way we currently know how to do this is by recreating the intense heat and pressure in the sun. We have perfected this process in a hydrogen bomb.
But to give you an idea of the difference between the two – for a conventional uranium bomb, like what we dropped in WWII, we get uranium to react by igniting conventional explosives around it. A hydrogen bomb requires uranium to implode on a sample of hydrogen. Meaning the only way we know how to get hydrogen to fuse into helium, here on Earth, is in the center of a nuclear bomb explosion.
How do we contain this in a power reactor? How do we feed and contain a nuclear explosion of this heat and pressure in a 55 gallon drum? That’s been the constant question of the past 50 years. So close and yet so far…. It’s a tantalizing promise that has been ripe for all sorts of fraud and foolishness.
The Science of fusion
Keep in mind, we can and do get hydrogen atoms to fuse into helium – on an extremely small scale. We collide individual particles all the time in particle accelerators all around the world. However, this takes energy – lots and lots of energy, accelerating individual particles to near light speed. The energy released by the fusion in this collision is a rounding error compared to the energy put in. What we need is to fuse enough hydrogen on a massive enough scale to release more energy than we put into it. We then need to contain that reaction and feed it.
To give you an idea of just how many particles we would need – about 2 grams of hydrogen would get us about 100 megawatt hours. That’s about about a million billion billion atoms. Meaning we’d have to do that many hydrogen collisions to get that moderate amount of power. So, it’s not going to happen with particle accelerators.
The only way to do it on this massive level is by mashing everything together with enough heat and pressure. The Tokamak reactor was our most popular attempt to date. It tries to maintain hot, pressurized hydrogen suspended in a powerful magnetic vacuum, which keeps it from touching any surface and cooling off. That came nowhere close to where we need to be, impressive as it may look.
A good analogy is getting a car to go a million miles an hour. Even if we somehow miraculously created an engine with that much horsepower, any car would fly apart long before we hit that speed. Saying we hit a new speed limit, which currently stands at about 1000mph, means nothing compared to where we need to be.
The sad fact is, our current technology is just too backwards for nuclear fusion on this massive level, and there’s no real sign of progress. After 70 years in the atomic age, our best science still says to just mash everything together with enough force, heat and pressure.
So what hope is there that allows us to bridge this chasm of technology? There are two ways an ordinary person can tell whether a claim is worth investigating any further.
One: have we made any scientific breakthroughs into understanding how atomic nuclei fuse together?
Two: have we made any engineering breakthroughs in how we can contain enough heat and pressure to fuel a fusion reaction?
The first one is the more fantastic. Pons-Fleischmann tried to capitalize on this idea with their idea of cold fusion back in 1989. However, the science didn’t stand up to scrutiny – it all amounted to a bunch of sophisticated sounding electronics which explained nothing about the deeper nuclear physics issues. Robert Park, a professional physicist and expert witness, wrote about them in his book Voodoo Science. More on that later.
We can look to fields like Quantum Field Theory for their latest theories on what keeps these subatomic particles apart and what makes them fuse. But this field actually tells us how separate these particles really are.
Modern developments therefore focus mostly on engineering. We can also look to chaos theory and thermodynamics to figure out how to manipulate pressure into small productive pockets – much like the ultra-high velocity jet engines (SCRAMjets) that are currently being researched. These too, however, are nowhere where we need to be to maintain fusion.
The Snake Oil
Two factors that play a major role in a courts determination of whether or not fraud has occurred are the relative sophistication of the parties and the economic stakes involved; when one of the parties to a deal is relatively unsophisticated and the other party stands to make a large amount of money, the likelihood of fraudis high. Nuclear fusion represents a perfect storm of both – the science is totally beyond almost everyone, and the potential for insane profits are a seductive siren song.
As Bob Park said when discussing cold fusion, extraordinary claims require extraordinary evidence. This means the responsibility of proof rests on whoever makes the claim of getting close to fusion.
The latest link I obtained from a nuclear fusion true believer, The Fusion Podcast, again talks a big game but is full of all the same talk we’ve been hearing for the past 50 years. There’s no new science, no new methods or engineering, it’s always the same thing: someone looking for venture capital, looking to dress up the same old methods as something new.
The Economist tends to have good articles which show just how much tension exists between venture capitalists and scientists in this field. A well-believed promise can easily gain millions from an adventurous but not too knowledgeable capitalist. But it’s more the “sucker born every minute” theory of P.T. Barnum than any nuclear physics theory at work here.
And then there are those who market the idea that we don’t have nuclear fusion because it’s all some conspiracy theory. But remember this – while engineering and techniques may be proprietary and secret, science is open to all. Likewise with nuclear fusion technology. The Pons-Fleischmann claimed their science was hidden, not because they uncovered some dark secret on their own, but because they had none. When nuclear physicists do come up with a breakthrough that easily lets us cross these nuclear barriers, we’ll know.
Whether modern science can actually do this, or whether we’re stuck in some cultural funk, is another question.
