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Can Nuclear Fusion Put the Brakes on Climate Change?

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Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#71

Post by cantagi »

d_theorist wrote: post #8

I used to be so excited about fusion, but then I actually learned more about it. Perhaps I'm missing something, but the benefits over fission seem underwhelming. It's about the same cost on a per-megawatt basis. Modern fission plants are totally safe. Nuclear waste is basically a non-problem, especially with the most recent technology. And fission has the huge benefit of being a mature, proven technology. What's the…

Since a commercial fusion reactor hasn't yet been developed, you can't argue that it is or will be the same cost per-megawatt as fission power. That's because you can't predict any advances in technology that make fusion easier or reduce the capital cost.

Based on a HN recommendation, I read this book: https://www.amazon.co.uk/Future-Fusion-Energy-Popular-Scienc...

The authors argue that ITER will get there and it's a matter of time, funding, and politics. SPARC might be able to get there around roughly the same time. Neither will be hooked up to the grid, but they will demonstrate the tech needed to make a viable fusion power plant. Unfortunately none of the other exciting fusion projects out there will be able to get off the ground due to fairly fundamental limitations.

If you ignore any tedious jokes about when fusion power will be ready, and assume it will be ready in a few decades, it's still a process that converts reasonable quantities of seawater into power, with no CO2 emissions, and is relatively safe compared to fission.

It won't be ready in time to reduce emissions enough to prevent catastrophic climate change. However, it can be ready soon enough to power the devices we'll need to sequester CO2 from the atmosphere once we've reduced our emissions to the point of diminishing returns.

After the concept has been demonstrated, there's plenty of scope for improvement which will make it better and cheaper. On the other hand, the price of oil will increase as emissions taxes are introduced (I hesitate to say that we'll run out of reserves).

There's a lot more mileage in fission technology that what's commonly deployed for power, but the new types of reactors needed make it far easier to produce weapons(). Also, although fission technology is mature and safe, the human factors around it are not, which will still lead to accidents, contamination, and deliberate theft.

() Fusion reactors would also make it possible to breed fissile material since they are a neutron source but it would be slower and easy to detect.

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#72

Post by [deleted] »

BitwiseFool wrote: post #23
leephillips wrote: post #13

Earlier quoted context omitted.

Heat is extracted to run a turbine, as with any reactor.

Where/how does the heat extraction take place? Are they planning to put water pipes in the walls of the confinement unit? I'm struggling to understand because in the diagrams I see a powerful magnetic field containing the particles, and then a near vacuum. Those two things alone must make heat transfer very difficult, no? I don't see where the produced energy gets extracted.

[deleted]

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#73

Post by simonh »

ip26 wrote: post #47
leephillips wrote: post #15

Earlier quoted context omitted.

It is not worth investing money in, because it will never supply grid power: http://progressive.org/op-eds/let-cut-our-losses-on-fusion-e... Here is another physicist warning about the hype just a few days ago: http://backreaction.blogspot.com/2021/10/how-close-is-nuclea...

It receives a pretty small level of funding, so I'm not quite sure there are many losses to cut. $2.2bn over 5 years is about $1.50 per person per year. It's comparable to the funding for the CPB.

ITER will cost about the same as the Manhattan project, around $21bn in 2021 $, and that's just one project. Total investment in Fusion globally is huge and the problem is at the moment there are multiple different feasible ways forward, and it's not clear which will pan out. There's huge risk of wasting large amounts of resources and time, even if we do eventually figure it out.

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#74

Post by simiones »

arichard123 wrote: post #53

SPARC is going to be relatively small in size. If they can make the commercial reactors as small as SPARC then they can be created in a factory. Which will make roll out and cost much better than fission.

SPARC will also not produce net power gain, as far as I know. They are planning to achieve "breakeven", which is energy going into plasma 2, with an optimistic expectation of Q ~ 10. But best estimates for plasma energy -> electrical energy conversions are 50% efficiency, and energy going into plasma is typically many times smaller than the amount of energy drawn from the grid (couldn't find any numbers for SPARC).

SPARC doesn't seem to publish such numbers, but ITER, which is aiming for Q ~ 10 is going to be nowhere near to generating net energy, so SPARC's 2 Edit: ITER is also going for Q~=10

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#75

Post by mzs »

goodpoint wrote: post #55
d_theorist wrote: post #8

I used to be so excited about fusion, but then I actually learned more about it. Perhaps I'm missing something, but the benefits over fission seem underwhelming. It's about the same cost on a per-megawatt basis. Modern fission plants are totally safe. Nuclear waste is basically a non-problem, especially with the most recent technology. And fission has the huge benefit of being a mature, proven technology. What's the…

> Modern fission plants are totally safe Unless there's a war. Unless corruption leads to poor management of the plants. Unless nuclear waste is mismanaged. Unless there is an earthquake or tsunami of completely unexpected intensity.

or corrosion of containment vessel, or an airplane strike…

http://green.blogs.nytimes.com/2010/04/21/critics-challenge-...

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#77

Post by simiones »

erazor42 wrote: post #5
devoutsalsa wrote: post #2

Probably not. ITER takes 440 megawatts of total power to generate 500 megawatts of power, at the cost of many years of development & billions of dollars. [1] [1] http://backreaction.blogspot.com/2021/10/how-close-is-nuclea...

From your article it's more: "Okay, so ITER will have delivered in that full demonstration that we could have okay 500 Megawatt coming out of the 50 Megawatt we will put in."

That's 50 MW going into the plasma. But they have to draw 440MW from the grid to deliver this power to dump those 50 MW into the plasma (lasers are extremely wasteful).

Also note, the 500MW are the power of the plasma - in the best case scenario, maybe 50% of that could be converted into electrical energy, the rest will be lost as heat.

So grid-to-grid, they will be taking out 440MW of power and putting back in 250MW. Except that is useless, so they didn't even bother with a turbine the full 500MW of plasma power will have to be vented as heat in ITER itself (DEMO will take over, and aims to deliver net power generation ~20 years after ITER is successful).

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#78

Post by willis936 »

simonh wrote: post #73
ip26 wrote: post #47

Earlier quoted context omitted.

It receives a pretty small level of funding, so I'm not quite sure there are many losses to cut. $2.2bn over 5 years is about $1.50 per person per year. It's comparable to the funding for the CPB.

ITER will cost about the same as the Manhattan project, around $21bn in 2021 $, and that's just one project. Total investment in Fusion globally is huge and the problem is at the moment there are multiple different feasible ways forward, and it's not clear which will pan out. There's huge risk of wasting large amounts of resources and time, even if we do eventually figure it out.

Creating conditions to split a heavy nucleus for 1 microsecond is much easier to do than fusing light nuclei steady state.

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#79

Post by simiones »

civilized wrote: post #40
d_theorist wrote: post #30

Earlier quoted context omitted.

That is true actually. Seems silly but it's actually a serious benefit! The main issue with fission is that people have become irrational about it. Maybe we get a fresh start with fusion.

Unfortunately, a lot of the same environmental interest groups that halted the scaling up of fission also hate fusion. It's best to think of fusion as a way to generate effectively unlimited amounts of energy, kicking in 50-100 years from today. This could be super useful for the long-term ambitions of human civilization - energy has been such a hard constraint for so long that people have barely thought about the am…

> generate effectively unlimited amounts of energy

I don't understand where this concept is coming from. The best ever fusion power experiments so far have not even produced 1 miliwatt net electrical power. ITER, if it succeeds in its 30 year timeline, will not be even close to engineering breakeven (net power generation) - they estimate 0.57 output power/input power ratio - with DEMO hoping to break even 20 years later.

Why is there this bizarre idea that we'll jump from to with fusion?

Re: Can Nuclear Fusion Put the Brakes on Climate Change?

#80

Post by orwin »

tambourine_man wrote: post #18
d_theorist wrote: post #8

I used to be so excited about fusion, but then I actually learned more about it. Perhaps I'm missing something, but the benefits over fission seem underwhelming. It's about the same cost on a per-megawatt basis. Modern fission plants are totally safe. Nuclear waste is basically a non-problem, especially with the most recent technology. And fission has the huge benefit of being a mature, proven technology. What's the…

>Modern fission plants are totally safe. Nuclear waste is basically a non-problem, especially with the most recent technology Please elaborate on both. And I think we can all agree there's no such thing as totally safe, only risk management.

Gen2, even with weird designs (so Fukushima included) are individually safer than any coal plant ever built, and the whole generation will kill less people, even counting those dying in a shameful, unprepared evacuation, that the new "clean coal" plants (with flue gas discharge) built in the western world since the 2000s. Not taking into account the GHG emissions. Number of death/GW is in the favor of nuclear for any power station, even when counting dislodged people as "dead" (in this case, hydro is actually the 2nd most deadly)

For the nuclear wast beeing a non-problem: i don't agree, but i understand where he is coming from.

There is basically 3 type of nuclear waste: low-activity waste is waste that we could ignore, and the most present. radioactivity levels are what is find in granitic area. Often indirectly contaminated materials, or very long-lived isotope (radioactive decay is long, the the material is not very radioactive). It can still be dangerous and create radon gas if poorly stored (as do caves in granitic areas). We have no good answer to that. Maybe separate long=lived isotopes from the rest, store it, and reuse the contaminated materials after waiting a dozen years, mixing it with new cement or something.

intermediate-activity waste: still extremely dangerous, its often contaminated material (filter, pipes), or active (and dangerous) isotopes, with a half-life of up 500 years (i think the most present have an half-life of 200 years, and you need 10 cycles basically to be rid of it). Those are not direct fission byproduct (i don't think so, i don't remember exactly, maybe a small number is?).

High-activity waste: This is the real dangerous stuff. Those can stay hot for years. There is to kind:

- direct fission byproducts. Some degrade not in stable isotopes, but in the intermediate-activity waste, so even with a short half-life, they take as long as the intermediate ones to get rid of (since they degrade into it. If i'm over-explaining, sorry). Some degrade into stable heavy metals that also poison the environment, in a different way.

- transuranic elements. The graphite from Chernobyl could be counted in this category? (not sure, if an expert is here, can you infirm this?). I do not exactly understand this category, but its basically elements from the reactor core that are not fission products.

The reason why GP said "Nuclear waste is basically a non-problem" might be because we are able to re-use some the fission products, and to deactivate the rest. Both technologies are at an experimental stage, the first one could be in commercial use in the decade if China doesn't fail. And since the fission product decay is what's create the most troublesome waste (half-life between 100 and 500 years mean the wast stay dangerous for between 1000 and 5000 years), its a "non-problem".

I don't have the material on hand, i learned that in 2019. i could find it again if you wanted (probably mostly be in French, sorry), and to be fair, i might have oversimplified things i did not understand in the first place.

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