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With the possible exception of Hulkamania, there is no force mightier than nuclear fusion. Pound for pound, it releases more energy than any fuel source ever used on Earth. It sustains the stars themselves, bringing the daytime and filling the night sky with the light of fusion fires so brilliant they can be seen light-years away. It is the furnace in which all but the simplest elements were forged, from the oxygen in your lungs that fuels your metabolism to the silicon in your computer that lets you read this article to the protactinium that just sits uselessly next to uranium on the periodic table doing nothing to justify its sorry existence.

Want to tap into that same power yourself? It couldn’t be simpler.

First, gather up around 1.989×1030 kilograms of hydrogen. Just call it “one nonillion, 989 octillion” if you need to say it out loud for some reason. Heat the core to a temperature of 15 million degrees Kelvin (roughly 25 million degrees Farenheit, for those who want a conversion), enough to get all those hydrogen atoms moving fast enough to overcome their natural mutual repulsion from each other and collide. Hydrogen atoms will fuse together into helium, releasing energy in the process, and you’ve got nuclear power!

Then, keep the reaction going by tightly confining this hellstorm in place despite its natural desire to blow outward. Conveniently enough, the tremendous gravity produced by the mass of an entire star will do both of these things for you. You now have a power source that releases enormous amounts of energy and produces virtually no pollution.

Star Fusion

Then just do the same thing again, except this time replace the mass of an entire star with a metal donut about 50 feet across. Oh, and since you won’t have the density and sheer size of the solar core to work with, you’ll need even higher temperatures; a hundred million or so degrees ought to do it.

That’s what a group of scientists in Germany have been working on with the Wendelstein 7-X, a type of experimental fusion reactor called a stellarator. Gas is injected into a torus-shaped chamber, where it is bludgeoned with microwaves and particle beams into a plasma with a temperature of millions of degrees. Superconducting magnetic coils ringing the chamber confine the plasma, controlling its flow and preventing it from touching anything in the interior of the stellarator that would react badly to contact with the core of a star.

Which is everything, so you really don’t want to cut corners on those magnets.

It’s still in its early days. The Wendelstein hasn’t even caused a fusion reaction yet, just shown promise that it can. On December 10th, 2015, the Wendelstein’s first successful test produced a helium plasma with a temperature of about one million degrees Kelvin. Its builders hope to eventually achieve temperatures of 60 to a 130 million degrees, over eight times hotter than the core of the Sun.

End even if the Wendelstein 7-X design does turn out to be the road to practical fusion power, there’s still a long way to go. Artificially causing nuclear fusion is one thing; that’s been possible for decades. (Over half a century, actually, though for a while it could only be done through laboratory-unfriendly means like setting off a nuclear bomb.) Causing fusion efficiently enough that you actually get more energy out than you put in is another, and doing that efficiently enough to make it economically viable as a source of electric power is yet another.

Still, it may well be possible, quite possibly within our lifetimes. What would some of the implications of that for our world be?

Preamplifier at the National Ignition Facility

1. Fuel

Traditional power sources have one thing in common: They’re a pain to get a hold of. Before coal, oil, natural gas, or uranium can be used for fuel, they must be extracted from the earth, at great expense and often at great risk. And before they can be extracted they have to be found, which is no picnic either. Energy companies and national governments spend tens of millions of dollars just looking for new sources of oil, never mind the expense of actually drilling it.

Even renewable power sources like solar, wind, and geothermal energy are not immune to the problem of supply. They’re effectively unlimited, but the places on Earth where they can be gathered most efficiently are not, so these technologies become less economical the more they’re used.

So imagine how much things might change if the world’s primary power source ran on water.

More specifically, imagine if it ran on deuterium, hydrogen’s roided-up isotope cousin. Unlike standard hydrogen, which has only a single proton in its nucleus, deuterium has a neutron as well, making it more suitable for fusion. Deuterium is far less common than regular hydrogen, well under one-tenth of one percent of the total hydrogen in Earth’s oceans… which means there’s still a staggering amount of it.

MAST plasma image

(A deuterium atom is also known as a “deuteron,” which I will I will not be using in this article due to methodological objections to words that sound really stupid.)

A fusion reaction could be fueled by deuterium alone or in combination with the even more swole hydrogen isotope tritium, which crosses the line from extravagant to outright gaudy (and stable to radioactive) with two neutrons. This would be easier to do than fusing pure deuterium, since it requires a lower ignition temperature to get started. Naturally occurring tritium is rare, however – actually rare, not just just rare by comparison to the most abundant substance in the entire universe. It can be produced artificially by bombarding lithium with neutrons, however, something that already happens as a byproduct of fission reactors.

For even more energy, you could use deuterium together with the isotope helium-3. Helium-3 – helium with one neutron instead of the usual two – is hard to come by on Earth, though it can be manufactured. (It’s what tritium decays into, actually. Small world.) It’s more abundant in lunar soil, which might someday make the Moon a source of it if it can be extracted at a reasonable cost. You’d have to sift through a lot of lunar soil to get a useful amount of helium-3, though – a better source would be the atmospheres of gas giants, most likely Saturn.

Fusion power would not be an instant substitute for all other power sources. Chemical fuels like gasoline cram a lot of energy into a more compact package than even the most sophisticated electrical batteries currently available, so even in a world of ubiquitous fusion energy you’re unlikely to see 747s trading in their jet fuel for a chance to plug in to the airport’s reactor. For pretty much anything that runs on electricity, though, practical fusion power could provide an almost limitless supply of energy.

2. Cleanliness

The primary sources of power used today leave quite a mess in their wake. Burning fossil fuels fill the air with methane, particulates, and a tediously long list of unpleasant substances ending in “oxide.” Nuclear reactors produce radioactive waste that will continue to be hideously damaging to living things so far into the future that the question of how to label deep nuclear waste disposal sites so that our descendants know not to open them 20,000 years from now is being seriously researched.

Fusion power offers tremendous advantages in this regard. The only potentially dangerous input or output of the fusion reaction itself is tritium, which is radioactive and not something you’d want to inhale or swallow but not nearly as noxious nor as long-lived as spent fuel from a fission reactor. And unlike most of what comes out of a present-day nuclear power plant, tritium is actually useful for things besides playing really, really mean-spirited practical jokes on far future civilizations that can’t understand warning labels written in English – it could bee used in deuterium-tritium reactors or stored until it decays into helium-3. The reactor core itself would also get nastily radioactive after a while, but it wouldn’t remain at hazardous levels of radioactivity for nearly as long as waste from a fission reactor.

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I don’t want to oversell here. Fusion energy is commonly portrayed as being perfectly clean. It isn’t. Hydrogen is difficult to contain, so some amount of tritium leakage into the environment is unavoidable. And you’ll probably want to keep your distance from a used fusion reactor core for at least a century or so. But compared to the torrents of toxic effluvia poured out by modern power sources, there’s really no contest.

3. Politics

UN Logo

Natural resources are not spread evenly around the world, and fuel is no exception. This has profound political and economic effects. Fossil fuel reserves can catapult otherwise peripheral nations, regimes, and ideologies, to global importance. Otherwise irrelevant patches of ground become worth fighting wars over.

There’s no reason a local conflict like the 1973 Yom Kippur War should have caused global economic chaos, for instance- except the United States and some of its allies were supporting Israel, and a cartel of nations who weren’t terribly fond of Israel controlled enough of the world’s oil production to quadruple the cost of oil in the United States. (Plus, it was the 70s. Almost everything sucked more in the 70s.)

Fusion power could change this dramatically, since deuterium can be harvested anywhere there’s water. No nation or group of nations would be able to pressure the rest of the world by threatening ti stop selling fusion fuel, or invading and conquering their deuterium-rich neighbors. No one would need to court the favor of foreign despots whose regimes dominate the world’s supply of seawater.

I suppose widespread use of helium-3 does raise the unattractive prospect of replacing nations fighting over oil on Earth with fighting over dirt on the moon. Luckily, gas giants are a better bet for helium-3 production, and anyone making a territorial claim to all of Saturn would probably have trouble making it stick.

4. Safety

The extraction and use of modern fossil and nuclear fuels produce a cavalcade of potential hazards to life, health, and property even when everything is going well. When they don’t go well, you can end up with oil wells engulfed in flames, or nuclear meltdowns spewing radioisotopes into the atmosphere, or an entire town that had to be permanently evacuated because it’s choked in the smoke of a coal mine fire that started in 1962 and is still burning.

Even “green” sources of power can be horrifically dangerous. During a typhoon in 1975, dam collapses at hydroelectric plants in China’s Henan province caused a flood that killed 170,000 people.

Fusion power, by contrast, would be extremely safe.

Fusion Explosion Nuclear Bomb

I cannot emphasize this enough: Fusion reactors can not cause nuclear explosions. I don’t know why so many works of popular fiction depict them that way, from superhero movies like The Dark Knight Rises and Spider-Man 2 to science fiction authors who put enough thought into the technical backgrounds of their stories that they really ought to know better (David Weber, I am passive-aggressively coughing in your direction.) But for some reason, they do. The depiction of fusion power in pop culture is like that running gag on “The Simpsons” where any vehicle that gets mildly jostled explodes catastrophically, except played completely straight.

The reason fusion is so safe should be clear once you remember how ludicrously hard it is to start and maintain an artificial fusion reaction in the first place. After all, the only place it occurs naturally is in the cores of stars! Fossil fuels are chock full of chemical energy that they release at the drop of a hat. Fissile materials like uranium are inherently unstable and emit a steady spray of radiation 24/7 even without any external provocation.

Fusion, on the other hand, is not some cheap floozy that just gives its energy to the first person who comes along with a lit match and a nice car. The fuel in a fusion reaction has to be kept at temperatures of tens or hundreds of millions of degrees, while also kept tightly contained despite the natural tendency of heated materials to expand. As soon as either condition is not met, the reaction quickly fizzles out. If for some reason a fusion reactor cannot contain its fuel – because it’s been breached, or the confinement mechanism malfunctions, or some super-villain sabotages it to make the reaction run even hotter than it should – the reaction stops.

If nuclear fusion happened so easily that it could continue after a reactor had stopped functioning properly and cause a runaway chain reaction, we’d already have practical fusion power by now! We’d all be living in some weird alternate universe where everyone drives electric cars, American foreign policy revolves around containing Maoist terrorists funded by the vast wealth from Bolivian lithium mines, and this article is about all the amazing things you can do with graphene.

Also, zeppelins would be in widespread use, because it seems like every alternate history has to have zeppelins in it for some reason.

5. Future Applications

1980s Nova Laser fusion

So what could we do with fusion power, besides saving money on the electric bill and finally escaping that nagging fear that an unquenchable coal fire might permanently shroud our hometown in an uninhabitable Silent Hill-esque miasma of choking fog? Here are a few possibilities.

Water is abundant on earth, but fresh water is not. Only around 2.5% of the water on earth is fresh, and much of that is frozen. As the world’s population grows, and per capita water consumption increases with growing wealth, this becomes more and more of a problem.

There is a solution to this: Desalination, the process of removing salt and other minerals from water for drinking or irrigation. There’s more than one way to do this, but they’re all energy-intensive, and slaking the thirst of billions of people and the farms that keep them fed with desalinated water is an extremely expensive proposition. Practical fusion power could make a tremendous difference here, providing huge amounts of electric power without depending on a fuel source whose availability is limited to the speed at which coal or oil uranium can be extracted from the ground.

Using fusion power to not die a torturous death from dehydration is all well and good, you might be thinking, but it’s not terribly exciting. Well, how about space travel?

Getting around in space is simple. Propel some mass in the opposite of the direction you want to accelerate, and Newton’s third law of motion sends you on your way. But if you want to accelerate quickly – and you do, because the distance between Earth and even its closest planetary neighbors is huge- you want that propellant mass to be moving as quickly as possible. Modern spacecraft do this with energy from chemical reactions, which requires a large fuel supply.

Nuclear fusion provides far more energy per unit of mass than any chemical reaction, allowing a fusion powered ship to carry far less fuel and reaction mass. If the energy of a fusion reaction could be properly controlled and directed, it could be used to accelerate propellant out of the ship at tremendous speeds. A fusion rocket-propelled ship could be capable of feats unthinkable with existing technology – a manned craft could be sent to Jupiter in a few hundred days, or an unmanned probe to nearby stars in only a few centuries rather than millennia.

It’s not exactly warp drive, but in the face of the challenges of real-life space travel that’s very impressive indeed. It certainly beats just sitting around on Earth.

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