It seems that for the last couple decades fusion is always 30 years away and by this point we’ve well passed the initial 30 and seemingly little progress has been made.
Is it just that it’s so difficult to make efficient?
Has the technology improved substantially and we just don’t hear about it often?
In: Physics
Similarly we’ve been 10 years away from self driving cars and a mission to Mars my entire lifetime
Eli5 response : “30 years away” is the response a give to my manager when it asks me “how long will it take to build this software?”. OK, not years in my case but days or months, you’ve got it. I have no clue so I give a time anyone can forsee.
For nuclear fusion it’s the response experts give to journalists for the sake of simplicity. Actually there are a lot of work to do and a lot of uncertainty to figure out before build a fully functional and scalable prototype and way more for a viable industrial facility.
30 years is about a generation of engineers. When you say “30 years away” you actually means “We are working hard on it so the next generation of engineers might be able to build it”.
The short answer is that it was never 30 years away. We straight-up do not have a practical path for creating a fusion reactor that can be used to generate power, and we never have.
Research, in general, doesn’t operate on predictable timelines. You could have a breakthrough tomorrow, or you might never figure it out. You might have 99% of what you need to make it work, but the remaining 1% is physically impossible. Or, more cynically, 30 years is close enough to justify funding, but far enough to not be held accountable for a lack of results.
Right now, we’ve got a fundamental problem with a fusion reactor, which is that we don’t have a way to contain a sustained reaction that doesn’t require more power than we’re getting out of the reaction, and we don’t have a way to get power out of the reaction while containing it. We’ve been coming up with better ways to keep a reaction going, but we’re still talking about micro-scale reactions.
Nuclear fussion isn’t just going to require “X more years of research”, it’s going to require a new technology that we don’t even have on the drawing board right now, and we don’t even know where to start drawing.
Because media likes to greatly misinterpret what scientists say. And that’s ignoring the engineering needed to convert the science project into a real application.
You can see a faster version play out in autonomous vehicles. Musk went marketing and got a ton of stock value out of it so everyone assumed it’s done. Almost 10 years later and we realize that not only it’s not done we don’t know when it will be.
Because we’ve spent 50 years investing so little in fusion that there’s never been any chance of it being developed in 30 years: https://youtube.com/shorts/BjJjvWQptHA
One issue that is not really spoken about is that the supply of tritium is insufficient to sustain all of the planned experiments, so there will be a bit of a crunch soon. You can breed it using lithium blankets but we still need to have it produced by nuclear reactors and there aren’t enough to sustain a fusion industry at the moment.
Because fusion means merging one atom nucleus with another one. However that is not easy, since equal charges repel each other, since ALL the atoms nucleus possess equal charge(positive – protons), they ALL repel each other.
Given that, fusion can only happens under EXTREME conditions, either when atoms are running really really fast(which means they’re really really hot), then they hit each other with tremendous amount of energy, releasing an EVEN BIGGER amount of energy in the process. Or when a gravity at the center of a star is so great, it forces one atom nucleus against the other.
How hot do we need to get? A few millions of degrees celsius within a star, hundreds of millions of degrees celcius within a reactor. Fact is, the Sun, or any other star cheats, due to the IMMENSE gravity they have, the atoms inside their nucleus don’t have a choice besides fuse with each other, releasing an enormous ammount of power during billions of years.
But that’s the issue, we can’t and never will be able to simulate a star’s gravity on Earth, hence we need to follow the first path, which is colliding atoms against each other at tremendous speeds and energy. To accomplish this we need to heat the gas into a really really high energy level, 150,000,000 ºC at least.
That’s the problem, we don’t and we can’t never have a material with a melting point that high, hence we need to isolate that soup made out of REALLY REALLY HOT atoms as far from the walls of the reactor as possible. Which fortunately is easy, atoms that hot can get isolated by exposing them to a really strong magnetic field, since with that temperature they attain a matter state called plasma, which basically means a soup of really really hot and ionized gas.
Then comes the second part, which consists to force this large cloud made out of plasma into a really really small area, in order to maximize amount of fusion taking place. That feat is REALLY REALLY HARD, since those atoms REALLY WANT to get as farther away from each other, because the repelling force I mentioned before. At the moment we didn’t manage to get more fusion energy OUT than we PUT INTO the reactor to attain these EXTREME conditions, but it’s theoretically possible and should be doable at least.
We are still decades away from a fusion reactor, and realisticaly we may never be able to pull this feat off, however if we manage to sustain a fusion reactor that outputs more energy than it consumes, we are going to skyrocket as civilization, since the fuel required to make it work is abundant and easy to get(both, lithium and deuterium are found in abundant levels within sea water, at much higher amounts compared to the fissionable atoms), one cup of deuterium and lithium(which is going to be breed into tritium) should be enough to release an energy compared to a barrel of oil burning away.
So it still worths the endeavour, stay tuned to the news, the ammount of effort and funding it’s taking is enourmous with many new players entering the race(startups aiming to generate fusion energy), and we may be surprised in the next years.
Fusion is possible *now* but requires a lot of resources to achieve or an undesirable fission reaction to start.
>Is it just that it’s so difficult to make efficient?
Sadly, yes. I use ‘sadly’ because there would be tremendous upside to fusion power. Getting two atoms to fuse that do not want to fuse takes astronomical amounts of pressure/temperature to achieve.
>Has the technology improved substantially and we just don’t hear about it often?
Yes, but not nearly as fast as we’d hope. There is a lot of motivation to achieve this so it’s not forgotten.
The ITER fusion reactor is scheduled to start in 2025. It will be a major advancement in fusion research.
Working as an Engineer, I’ve often said when it comes to completing projects “You first complete 90% of a project. Then you complete the *other* 90%”.
The last 10% of project often takes much longer, as it often involves looking for errors, resolving those errors and when you fix those errors you end up having to go back and redo things that were perfectly fine, and then in redoing that you need to change something else…
This can go on a long time.
It’s going to be much worse with a technology that has never existed before. I suspect that once(if) the first practical fusion reactor is built, we will see 3 or 4 others pop up in under 5 years. That’s the way technological innovation usually works.
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