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U.S. physicists rally around plan to build fusion power plant

sciencemag.org

201–210 of 240 posts

Re: U.S. physicists rally around plan to build fusion power plant

#201
post #2

How much of the excess renewable energy is being wasted rather than stored? Maybe fuel generation like hydrogen or ethanol, or kinetic can help make nuclear less crucial?

Ethanol is wasteful, hydrogen is a beast to store, kinetic requires too many moving parts. If you want to store renewables you should turn them into methane, best storage volume, safe and proven hardware for storage, transportation and power generation. It’s even better if you can efficiently obtain atmospheric CO2 for the reaction, closes the loop. Honestly, fission is probably the best 0 carbon power technology tho…

> blows everything out of the water

I guess that's kind of what I am afraid of. Plus the issue of waste storage.

Re: U.S. physicists rally around plan to build fusion power plant

#202
post #130

Are at an inflection point for fusion power? With interest and funding for it finally gaining steam? I’ve noticed several announcements about independent efforts this past year [1–6] but not sure if (a) it’s always been this way or (b) my view is skewed by HN. [1]: https://news.ycombinator.com/item?id=21806334 "General Fusion" [2]: https://news.ycombinator.com/item?id=23979608 "ITER" [3]: https://news.ycombinator.com…

Yes, yes we are at an inflection point. But maybe not the kind you are thinking of. There will never be a commercial tokamak power plant. There has never, at any time, been any reasonable expectation of getting practical, commercial power from magnetic-confinement hot-neutron fusion. Renewables, with practical energy storage, will always be much, much cheaper than fusion could ever have been, even if it could be made…

>There has never, at any time, been any reasonable expectation of getting practical, commercial power from magnetic-confinement hot-neutron fusion.

Not true. The existence of privately-funded fusion efforts implies that some people think there is a reasonable expectation, and are willing to put money behind it. This costing study suggests that $2-6/W could be achievable for some fusion concepts[0]. Using some rough calculations, that would translate to $20-60/(MW*hr), which is competitive.

>Any practical fusion plant would have to absolutely huge -- an order of magnitude bigger than the biggest fission plant.

Not necessarily. Fission power plans with low power density have been operated, and may even be desirable from a safety standpoint. The current crop of small modular reactors for fission seems to target power densities in the range of 1-10MW/m^3, rather than the 50-100 MW/m^3 of PWR reactors. This suggests that reduced power density may pay off in terms of reducing the costs associated with risk mitigation (highly redundant systems, large containment structures, etc). Fusion reactors could probably get to the 1-10MW/m^3 range.

> "Break-even" is nowhere near enough to get practical power out

Yes, there's a distinction between 'scientific breakeven' of gain > 1, and 'engineering breakeven' of gain > 10 (ish) which is necessary to have net power output. But we gotta crawl before we can run. It's an important milestone along the way.

>Tokamak fusion research is, first, foremost, and always, a jobs program to maintain a population of high-neutron-flux physicists

Not really -- the high-energy-density plasma physics research (which is not tokamak-related at all) is more relevant in terms of producing people with the skills to work on weapons.

> They need enough billions poured into the project to make it politically self-sustaining, where no amount of failure can ever threaten its funding, because so much has already been sunk that it would be too embarrassing to admit failure.

I'll admit that I see aspects of this, particularly with the failure of NSTX-U & politcally-motivated decision to repair it. However, what I mostly see with the DOE has been trying to get the most of the 'sunk costs' by slowly ramping down the program (ie, not investing in new devices to replace old ones that are shuttered). I suspect that Synakowski's reasoning was: "if a breakthrough happens somewhere around the world, it's worth having a skeleton program in the US that can be ramped up to take advantage of it at that time." Now that Van Dam has taken over, I think we may be seeing more optimism & willingness to invest, particularly if that means partnering with industry (which is trending in Washington).

[0]https://woodruffscientific.com/pdf/ARPAE_Costing_Report_2017...

Re: U.S. physicists rally around plan to build fusion power plant

#203
post #162

Earlier quoted context omitted.

Just the US value from https://en.wikipedia.org/wiki/List_of_countries_by_total_hea... vs #2 (Switzerland) is $US800 000 000 000 for all US residents in extra spending.

I'm confused by these data. It's common knowledge that the US spends much more per capita on Healthcare, however the commonly offered explanation for this is that the private healthcare system in the US is less efficient than the public systems in Europe. But the graph in the provided link shows that US costs are split evenly between private spending and public spending. This is confusing because the private system i…

The gov't portion includes basically everyone over 65 via Medicare, who have a disproportionate share of healthcare needs.

Re: U.S. physicists rally around plan to build fusion power plant

#204

I think that solar/wind + battery (e.g. Tesla Megapack) will make fusion irrelevant.

Miniaturized fusion (I know, a long way from this -- but so were computers) would revolutionize everything. Including transit, shipping, airlines, and other industries where batteries won't quite cut it (not to mention deep-space exploration).

As far as we know, it's not possible to miniaturize fusion. The mass of the shielding alone for a hypothetical miniature DT fusion reactor would prevent it from being used in anything smaller than a large ship. 'Advanced fuels' with reduced neutron radiation are orders of magnitude below DT in power density for given reactor performance levels, so miniaturizing them is even more in the realm of science fiction.

Re: U.S. physicists rally around plan to build fusion power plant

#205

Earlier quoted context omitted.

I'm not a fan of this sentiment. Sometimes things are just really f'ing hard, and no amount of "pushing people" is going to change the reality of how long those things take. I mean, if you look at both Tesla and SpaceX, nothing they've done was thought to be "impossible" from the outset from a scientific perspective . Electric cars already existed when Tesla was started, and we've been shooting rockets into space for…

While you are right that Musk favors engineering/cost improvements on existing ideas. I don't think there's a clear dividing line between science and engineering. SpaceX has numberous "firsts", including reusable rockets and some engine designs. So it's not right to say they just do things we've been doing for decades. And on the other end, the physics behind fusion is pretty well understood. The difficulties/expense…

>We call that "science" mostly because it is a state funded project.

Interesting perspective. I agree that arguably most of the difficulties are more in the applied side of things, although calling it engineering might be going too far.

The big looming physics uncertainty is crossing the 'burning plasma' threshold, where the plasma becomes dominantly self-heating. There are two aspects to this: (1) will the plasma settle into a nice self-consistent steady state? (2) will the large quantity of fast fusion-born helium nuclei destabilize the plasma in an unexpected way? Theory says it should work, but the proof is in the experiment (which is why SPARC & ITER are being built).

Re: U.S. physicists rally around plan to build fusion power plant

#206
post #101
post #97

Earlier quoted context omitted.

You are talking about fission, not fusion. Nuclear plants are using radioactive sources like uranium to generate energy. Fusion tech would use hydrogen and fuse it to helium.

Yep, and it is not just feasible but easy to build fission plants right now and stop using greenhouse-gas emitters entirely, but we won't, because Reasons. Our collective focus is being distracted from that working, clean, but politically-disadvantageous tech to this non-functional speculative future-tech that the author simultaneously insults.

People love to post comments like this on every thread where nuclear comes up, but it really distorts the reality of the situation.

Investment in nuclear has essentially evaporated. This is because fission plants take billions of dollars and around a decade to stand up. If you go through the numbers the ROI looks pretty ugly. Meanwhile you can look at the trend over time in levelized energy costs and storage costs, and can see that we're very near the thresholds for simply doing it all with renewables plus storage. All together this makes it clear to any investor doing the most basic of diligence that fission is a risky bet. Even if you waved a magic wand and eliminated any form of political opposition, that doesn't change this less than favorable cost picture.

Re: U.S. physicists rally around plan to build fusion power plant

#207

Ok, say I've got a new design for a fusion reactor, but it takes me 5 years to convince anyone that it's worth investigating. Fusion power has been set back 5 years. Someone please help me evaluate my design. Please! http://www.DDPROfusion.com

Fusion physicist here. What's to prevent you from evaluating it yourself? I would start with Todd Rider's PhD thesis https://dspace.mit.edu/handle/1721.1/11412 See if you can convince yourself that the arguments he makes about non-equilibrium systems don't apply to your concept, and then write a white paper explaining your argument.

I've read Rider's thesis several times. The ions in my device have a thermal energy profile. The coordinated motion is a result of their rapid expansion and cooling in a very weak magnetic field.

The instant ions leave the hot thermal focus, each one flys off on its own independent cyclotron trajectory. Their collective motion results in another dense, hot, thermal focus one period later.

Re: U.S. physicists rally around plan to build fusion power plant

#208

2040s? 20+ years from now!?! Too fuckin slow!! For all Musk's faults, he recognizes such timelines are untenable, and pushes people to do the 'impossible'.

>2040s? 20+ years from now!?! Too fuckin slow!!

I'm impatient too, but perspective is important here. Even the leading private efforts don't have plans to put power on the grid for at least 10 years. Also, before this report, there wasn't an official plan of any sort for the US federal fusion program to get to a pilot plant -- so this is progress. (FWIW, I participated in the early community input stages of this report.)

>For all Musk's faults, he recognizes such timelines are untenable, and pushes people to do the 'impossible'.

Musk has a good nose for what's possible to commercialize in a medium-term (5-10 year) time horizon on a few $bn budget. I have reason to believe he's considered fusion (he has a background in physics after all). Instead, he's made a play in batteries & solar.

Now, if someone had ~$1-5bn to gamble, it might be possible to leapfrog the existing crop of private efforts by ~5 years. Just pick one concept and build the engineering-breakeven experiment (gain ~ 20) without the intermediate scientific-breakeven experiment (gain ~ 1). It would be significantly riskier, but it would save time if it worked.

Re: U.S. physicists rally around plan to build fusion power plant

#209

Earlier quoted context omitted.

Fusion should lead to unbeatable specific impulses, so the huge size of a reactor may not be a problem at all. (Or maybe it is, I don't think anybody can be sure before there are actually working reactors out there.)

Since we're talking about things that don't exist: - We should be able to beat fusion's Isp with direct matter to energy conversion. Certainly the mass of fuel needed will be 3 OM lower. Edit to add: Isp is a measure of velocity. The thing about velocity is, energy goes quadratically but momentum imparted to the vessel (the impulse) only goes linearly with velocity. Since no process can be 100% efficient, you're deal…

Well, if you create a nice way to make and store anti-matter, you would basically solve rocketry on any place that humans could ever care about going to.

There are people researching that too, but not as many as fusion. And well, determining the capacity of things that don't exist is the first step on the work of making them exist.

Re: U.S. physicists rally around plan to build fusion power plant

#210
post #198
post #114

Earlier quoted context omitted.

Not sure about the plural thing? In my own field a paper using singular forms would really stand out. Why remind readers and reviewers that you are working alone in every single sentence? Genuinely interested to hear your reasons! This is an issue for the paper I am currently working on. Naturally I would prefer to use the singular where it is accurate, and if I were better established I would.

This answer explains nicely why the “editorial we” is OK in papers...: https://academia.stackexchange.com/questions/2945/choice-of-... Short version: because it can be read as “we, the author and the reader”. But the site above uses phrases like “we have been granted a patent”, which come across as somewhat dishonest, making it appear on first glance as though this is the work of a team, corporate body, or at least t…

I've had several mentors and advisors and am doing everything I can to be inclusive without giving away equity. There was a legal entity created, and I have applied for several grants. Each time, I have put together a team or had lined up collaborators who could help if the grant had been awarded.

I'm working with suppliers, and discussing the concept openly with everyone who is interested.

Most of the time however, I am working alone.

Should I pay someone to sit around and twiddle their thumbs for semantic reasons?

I believe a royal "WE" is appropriate, but I could be wrong.

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