Nations collaborating to build world's largest tokamak | Hacker News Reader

Nations collaborating to build world's largest tokamak

iter.org

" plant will use this heat to produce steam and then electricity by way of turbines and generators"

Has anyone thought of a better way to "harness" power to produce electricity than heat? I'm guessing in the future there will be a more efficient way that changes how we think about the production of electricity.

If we manage aneutronic fusion, the output will primarily be fast-moving charged particles, which could be converted to electricity without a heat cycle. Helion, Tri Alpha, and LPP are all attempting aneutronic fusion reactors that would work this way.

The ugly truth is that the means of capturing the power really isn't the major hurdle to ITER. If you can get better than breakeven fusion in a containment vessel that won't be broken down by sputtering from fast neutrons, with the densities and temperatures you need for longer than a microsecond or two, all while breeding your own tritium, that would be the miracle. Unfortunately ITER has not come close to that, and really no one else has either .

The efficiency of modern steam turbines is not too bad. And considering that a lot of energy is used for water heating anyway, the overall efficiency (term: co-generation) is even higher.

Importantly, according to this

https://physics.stackexchange.com/a/191465/7911

the efficiency of steam is not far from the thermodynamical maximum under the assumption that the nuclear energy is initially converted into thermal heat in solid objects. You can do better, but only by harnessing the fission products (neutrons, protons, etc.) themselves before they thermalizes with surrounding material. This is possible, but it's a completely new and separate challenge in nuclear engineering, with a maximum improvement of about a factor of 2 in energy efficiency.

https://modernelectron.com/ maybe?

The one who invents a heat-to-electricity converter with suitable efficiency will be the winner of XXIst century. In nuclear installations, we're around 33% efficiency (plus, notably, half this electricity is produced during night). I read about Seebeck generators (heat-to-electricity with no moving parts), but they're even less efficient, and all those generators require a source of cold and warm it up. https://en.m.wikipedia.org/wiki/Thermoelectric_generator

A turbine can extract energy from the expansion of any hot gas. I suppose steam is common because of how easy it is to access liquid water and concentrate it around your heat source.

Wind, solar, hydro

The fun thing there is that other than photovoltaics, maybe (I don't personally understand them well enough to say for sure), the other two alternatives you are mentioning are also "nuclear -> heat -> mechanical force -> electricity" chains :)

Is just that some of the infrastructure is pre-existing.

My understanding of this was that basically we have achieved the scientific break even point already. That is we can have short lived fusion in a tokamak where we produce more energy than is consumed by the reaction. The trick is getting to practical break even: you also need to power the magnetic field.

It seems that we are getting closer with every attempt to getting to that break even, but it is very slow progress. I also remember reading something about an attempt at building a tokamak that didn't run continuously, but in short bursts. The idea was that it was more feasible to actually get closer to the break even that way.

Anyone have a quote in what our current best efficiency is?

I saw this a while back and thought it was a good summary: https://youtube.com/watch?v=L0KuAx1COEk

I forget the current best efficiency, but it's getting close.

> ITER will not capture the energy it produces as electricity, but—as first of all fusion experiments in history to produce net energy gain—it will prepare the way for the machine that can.

So this is a very large and expensive project that will never produce any actual electricity. Seems at high risk for budget cuts. No one can predict the political environment over the next decade. If it's anything like the last ten, this project is at risk even of they can stay on schedule and within budget.

Our irrational prioritization of public spending is seriously disheartening.

On one hand we have ITER, an international ~$20B R&D investment that pays dividends even if it fails - and America's 10% commitment is rightly seen as politically uncertain.

On the other hand, American's almost take for granted that we must spend $300B every year on war in the Middle East - for inarticulable and unquestionable reasons.

Imagine where we would stand if we turned just 10% of that fraction of our total military budget towards advanced R&D... commercialized fusion would literally revolutionize the world, and the technology would be an irresistibly compelling diplomatic carrot (esp. in the Middle East, in the form of cheap desalination)

At the current state of world affairs I agree with your skepticism. But there have been similarly expensive multinational projects that have and continue to survive difficult world conflicts and tensions: ISS.

But are they going to be leapfrogged by the stellarator?

Here is a good explanation of the differences between these two types of reactor:

https://m.youtube.com/watch?v=vqmoFzbZYEM

2035 is a long time from now. Hope someone hatches a practical energy plan in the meantime.

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