[HN Gopher] MIT-designed project achieves major advance toward f...
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MIT-designed project achieves major advance toward fusion energy
Author : klintcho
Score : 834 points
Date : 2021-09-08 19:50 UTC (1 days ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| NiceWayToDoIT wrote:
| I remembered that in 2018 Japanese team manage 1200 T peak power.
| http://www.sci-news.com/physics/strongest-magnetic-field-ach...
|
| In comparison, 20T does not look much, but again it is, I wonder
| with the Japanese technique what is the highest continuous
| magnetic field.
| uj8efdjkfdshf wrote:
| These high magnetic fields are generated using flux
| compression[0], in which the incompressibility of magnetic
| field lines means that compressing the coils generating the
| magnetic fields will increase the strength of the resultant
| magnetic field. However, the implosion process permanently
| destroys the magnet, which makes it highly unsuitable for
| continuous use and certainly shouldn't be used anywhere near
| your fusion reactor.
|
| [0]
| https://en.wikipedia.org/wiki/Explosively_pumped_flux_compre...
| pfdietz wrote:
| 1200 T has a magnetic pressure of about 5.7 megabars (about 20x
| the detonation pressure of high explosives). Such high fields
| can only be achieved very briefly in devices that explosively
| disassemble.
| sbierwagen wrote:
| Every mass-media article on fusion seems obliged to use "the fuel
| comes from water" line. I wonder if a "just says in mice" style
| harassment campaign would get journalists to stop saying this.
| rpmisms wrote:
| The journalists are saying that because the PR people tell them
| that. If I were doing PR for a fusion project, I'd sell that
| aspect hard--it's technically true, and sounds great.
| ncmncm wrote:
| Journalists quote promoters. When something has no reasonable
| prospect of ever producing, promoters resort to lying.
| Journalists are not responsible for it, although experience
| should make them less credulous. But pie in the sky sells
| better than skepticism.
| FredPret wrote:
| It's now only twenty years away!
| dfdx wrote:
| Plenty of skepticism in these comments. I've been following CFS
| for a while and can present a point of view for why this time
| might be different.
|
| Fusion energy was actually making rapid progress in the latter
| half of the twentieth century, going from almost no power output
| in the fifties and sixties to a power output equal to 67% of
| input power with the JET reactor in 1997. By the eighties there
| was plenty of experimental evidence to describe the relationships
| between tokamak parameters and power output. Particularly that
| the gain is proportional to the radius to the power of 1.3 and
| the magnetic field cubed. The main caveat to this relationship
| was that we only had magnets that would go up to 5.5 Tesla, which
| implied we needed a tokamak radius of 6 meters or so in order to
| produce net energy.
|
| Well that 6 meter tokamak was designed in the eighties and is
| currently under construction. ITER, being so large, costs tens of
| billions of dollars and requires international collaboration; the
| size of the project has led to huge budget overruns and long
| delays. Recently however, there have been significant advances in
| high-temperature super conductors that can produce magnetic
| fields large enough that we (theoretically) only need a tokamak
| with a major radius of about 1.5 meters to produce net gain. This
| is where SPARC (the tokamak being built by the company in the
| article) comes in. The general idea is that since we have
| stronger magnets now, we can make a smaller, and therefore
| cheaper tokamak quickly.
|
| Small tokamaks do have downsides, namely that the heat flux
| through the walls of the device is so large that it will damage
| the tokamak. There have been breakthroughs with various divertor
| designs that can mitigate this, but to the best of my knowledge
| I'm not sure that CFS has specified their divertor configuration.
|
| This was just a short summary of the presentation by Dennis Whyte
| given here [0]. I do not work in the fusion community.
|
| [0] https://www.youtube.com/watch?v=KkpqA8yG9T4
| sigmoid10 wrote:
| >The general idea is that since we have stronger magnets now,
| we can make a smaller, and therefore cheaper tokamak quickly.
|
| It's not that simple. The big problem with magnetic confinement
| fusion is that you need to control turbulence in the plasma so
| that you can contain the reactions for a reasonable amount of
| time to extract useful energy. However, turbulence increases
| with stronger magnetic field gradients, which is exactly what
| you get when making a smaller reactor chamber with stronger
| magnets. This wouldn't be the first project claiming to be able
| to build a small reactor, only to discover that it's virtually
| impossible without a major theoretical breakthrough. This is
| usually left out in the venture capital advertisements for
| these fusion startups. There's a reason why so much money and
| effort is spent on ITER - it is the only more or less
| guaranteed path to fusion with the tech and knowledge we have
| today.
| zetalyrae wrote:
| I've always wondered: why exactly is ITER so expensive, and
| slow? Is the engineering required at such a standard that it
| should takes decades of planning and construction and tens of
| billions of dollars? The timeline is so dilated (started in
| 1988, first plasma planned for 2025!) it feels like the kind of
| project that's expected to be cancelled from the start.
|
| It just doesn't strike me as obvious that reducing the major
| radius by a few meters would have such a huge impact on
| cost/timelines.
| thescriptkiddie wrote:
| I have a pet theory that the major cause for cost/time
| overruns on large projects is the cost constraint itself. In
| other words, attempting to do things on too small of a budget
| results in the overall cost increasing, not decreasing. I
| suspect that there are a few main mechanisms for this:
|
| 1. As budget constraints tighten, the number of man-hours
| spent wrestling with bean counters (and/or waiting around
| with nothing to do until the bean counter wrestling
| completes) increases exponentially.
|
| 2. "Cheap solutions" often end up being unfit for purpose,
| and have to be reworked later at great expense.
|
| 3. Budget overruns lead to time overruns which lead to more
| budget overruns, ad infinitum.
| TheSpiceIsLife wrote:
| Also, it's a multi-national government funded program that
| was never intended to return a profit.
|
| So there's very little incentive to constrain costs.
| ncmncm wrote:
| The budget overruns are the _whole point_ of the project.
| Any sort of apparent science or engineering goal is a
| smokescreen.
| IntrepidWorm wrote:
| Citations? Or just idle theorizing?
| ncmncm wrote:
| It is the same process we see everywhere that massive
| cost overruns and unlimited delays manifest. Modern
| management methods can control cost and schedule where
| that is an actual goal. Where they don't demonstrates the
| actual goal. Every penny of cost overrun goes into some
| pocket. Smart management ensures many, many pocketholders
| are allied to keep the gravy train running.
| IntrepidWorm wrote:
| Don't attribute to conspiracy what can be adiquately
| explained by beurocracy.
| ncmncm wrote:
| Millions of large buildings, and tens of thousands of
| huge ships, dams, and bridges are built on time and on
| budget.
|
| The alternative would be that management cannot be judged
| on its results.
|
| _Some_ bridges, invariably urban, go massively over
| budget and schedule. Urban tunnels, routinely. Military
| procurement, routinely. Are people who manage those
| systematically dumber than the rest? Or do they have
| different measures of success?
|
| What is common to those apparent failures is that they
| serve as a reliable, legal, long-term conduit from public
| funds to a multitude of private pockets. F-35 can never
| be cancelled, no matter what, because it has
| subcontractors in 48 states. The F-35 is a massive
| success to its backers: it secured monumental patronage.
| That it can actually take off and land, too, is a
| miracle.
| Edman274 wrote:
| An experimental fusion reactor is not a large building,
| or ship, or dam, or bridge. We've been building large
| buildings since the pyramids of Giza. We've been building
| large ships since before the Dreadnought. We've been
| building large dams since at least the Great Depression.
| The same goes for bridges. I don't think it's
| intellectually honest to compare budget and time overruns
| for fusion reactors to budget and time overruns for
| skyscrapers. You kind of say it without realizing it -
| "millions of large buildings", well yeah: if we have a
| lot of practice doing something - like building millions
| of large buildings - then wouldn't you expect us to do a
| better job of being on time and on budget than the
| handful of research efforts into the holy grail of energy
| production?
| ncmncm wrote:
| This is not a comparison of "budget and time overruns for
| fusion reactors to budget and time overruns for
| skyscrapers". It is a statement about management
| practices, regardless of the project.
|
| The statement is that a blue-sky project such as a fusion
| system is easily recognized by people on the lookout for
| sources of unlimited money with no strings attached. When
| they get control of the project, the bulk of the money
| will not end up spent on the extremely difficult problems
| entailed. If the problems are as difficult as expected,
| handing the money over to people who benefit by _not_
| solving them will reliably fail to solve them.
|
| We know with absolute certainty, already, that there is
| no "holy grail of energy production" at the end of it.
| The most favorable imaginable result is a system much
| more expensive to operate than a fission plant that
| produces no more power.
| liamwire wrote:
| Or, Occam's razor. A sufficiently complex engineering
| task can exist such that it fully taxes even
| international, multi-nation state-backed parallel
| capacity for engineering, and science.
|
| This is already demonstrated by your own examples
| provided, just at a smaller scale.
|
| If there were ever such a project to push against the
| capacity of our ability to do truly enormous, complex
| engineering, I'd say a massive, cutting-edge fusion
| reactor is as good a candidate as one could propose.
|
| Moreover, the economic and educational stimulus these
| projects provide cannot be ignored when accounting for
| the indirect, long-tail returns this project, and those
| similar, provide.
|
| Put another way: ostensibly, achieving net energy gain
| from fusion is the end of our near-term (energy) needs,
| conveniently breezing over the evolution and refinements
| of any system, as well as delivery and storage, but these
| are paths that are comparatively well mapped out. It then
| follows that, short of catastrophic losses prior to
| succeeding (which while not a given per se, seems more a
| function of time than of ability outright), any
| reasonable cost is worthwhile. Reasonable, in this
| context, meaning one that doesn't bankrupt, or otherwise
| severely impact the participants in a negative fashion.
| Given the scale of these budgets vs. that of social
| welfare programs, military spending, etc. I don't see
| that as an issue worth being concerned over. One can know
| the budget has been exceeded, without that also bringing
| down the house.
|
| Ultimately, to an extent you're asserting a false
| dichotomy. It can be true that there's continued,
| substantial progress towards the stated goals of these
| projects, even if the budgets, horizons, and timelines
| aren't to your taste. It can also be true that there's
| waste, inefficiencies, and even (both legalised and
| otherwise) corruption. One does not preclude the other.
| ncmncm wrote:
| It doesn't matter what physics you get when _none_ of the
| absolute fortune spent over decades ends up contributing
| toward a resulting source of commercially competitive
| power.
|
| We know already that if the project achieves all of its
| projected goals, the result will be much more expensive
| than fission. We know already that if any power is ever
| generated, at any price, it can come no sooner than
| decades in the future.
| craftinator wrote:
| > Modern management methods can control cost and schedule
|
| Perhaps the stupidest, most vacuous comment I've read
| this week.
| ethbr0 wrote:
| Time has its own cost, especially multi-stage construction
| projects.
|
| Being delayed imposes costs on downstream work, which must
| now be ready but in some kind of holding pattern, which
| imposes costs on work downstream of that work.
|
| So a large part of throwing "Manhattan project" / excess
| funding (and the potential savings by just funding it that
| way from the start) is avoiding these delays, to the extent
| possible.
|
| It costs +$200,000 to tackle some challenge in a critical
| piece? Sometimes it's cheaper just to pay.
| orbital-decay wrote:
| Expensive because it's a custom built physics lab, not a
| commercial power plant. Slow because it's an international
| project. Not just that, but it also requires lots of
| infrastructure to be built and entire industries to develop
| in multiple countries, before it can be useful. ITER is
| massive, but it's also just a tip of the iceberg.
|
| _> It just doesn't strike me as obvious that reducing the
| major radius by a few meters would have such a huge impact on
| cost/timelines._
|
| It would, easily. Past a certain size, production costs rise
| exponentially and require one-off tech.
| lumost wrote:
| If production costs rise exponentially with reactor size
| then the exponential power gain with size isn't very
| impressive.
| onlyrealcuzzo wrote:
| Is it massive because it's 6 meters? Like - a 6 meter
| diamond would be "massive" - but a 6 meter boat isn't that
| impressive.
|
| Or is it massive like the tokamak is a 6 meter engine to a
| 100 km collider? Like there's a ton of other stuff being
| built in a massive structure?
| dodobirdlord wrote:
| A 6 meter superconducting magnetic containment vessel is
| massive, as such things go. But ITER is also an entire
| facility built around the containment vessel.
| tibyat wrote:
| I agree. The responses in this thread are weak. Throw out
| any statement and claim it supports the known conclusion,
| how can you be wrong?
|
| "Well the volume (of a sphere) is proportional to the
| cube of its radius, so of course the cost of these
| physics experiments does as well" -- Why waste our time
| LeegleechN wrote:
| It's just an absolutely giant construction project. The mass
| and volume of the construction goes as the cube of the major
| radius of the reactor. Back of the envelope, SPARC is
| (6/1.5)^3 = 64 times smaller than ITER. The construction
| budget for SPARC is ~$500M, so ITER being tens of billions is
| in line.
| bigyikes wrote:
| How do projects like LIGO ever get completed? I'm probably
| totally naive here, but I thought LIGO is physically larger
| and has many difficult constraints. The LHC comes to mind
| as well, and that absolutely dwarfs ITER in physical size.
| What's the difference? Dealing with heat output?
| Superconductors are really hard maybe?
| sbierwagen wrote:
| LIGO did take decades to construct, like the LHC.
| According to LIGO's wikipedia article, it was the most
| expensive project ever funded by the NSF in 1994.
| neltnerb wrote:
| LIGO's size is also deceptive, the legs are kilometers
| long but the design is an L with the important bit being
| to vibrationally isolate things, maintain dimensional
| stability, and maintain vacuum.
|
| ITER is likely bigger in terms of volume of concrete or
| actual footprint.
| jvanderbot wrote:
| Margin?
|
| Akin's law of spacecraft #29 "To get an accurate estimate of
| final program requirements, multiply the initial time
| estimates by pi, and slide the decimal point on the cost
| estimates one place to the right."
| ncmncm wrote:
| ITER is a victim of a process seen frequently in large
| public-works projects, but particularly those where no one
| understands what anything really should cost, and where there
| is no practical deadline for completion. It is worst when
| there is no expected utility when it is done.
|
| We see it lately in the numerous military procurements
| (particularly the F-35 program), in NASA's SLS rocket, in
| California's bullet train to nowhere, and urban tunnels such
| as New York's 2nd Avenue subway extension. It is why nuke
| plants are invariably so expensive and late.
|
| In a word, _corruption_.
|
| Lately, this corruption has been arranged to be wholly legal,
| so there is no possibility of prosecution. The majority of
| the money spent is funneled into myriad private pockets
| without moving the project toward completion. Nobody
| involved, at the monetary level, has any desire for it ever
| to be completed, because that is when the gravy train stops.
|
| Fusion projects represent the worst case of this phenomenon.
| Nobody knows what it should cost, and nobody in control of
| spending wants it over with, ever.
|
| The chance that anything of any practical use could come out
| at the end was openly foreclosed before it ever started: it
| was never promised to produce any electrical power, and no
| turbines, or space for any, appear in any site plan.
|
| Any sort of practically useful Tokamak plant would need to be
| overwhelmingly bigger and more expensive than ITER, and could
| never come anywhere near producing commercially competitive
| power, so the project is a known dead end, to be milked until
| it is finally cancelled in shame.
|
| What is tragic is that each euro diverted to this boondoggle
| brings climate disaster terrifyingly closer.
| coryrc wrote:
| Hey, that's not fair, there were many people "working" on
| the 2nd avenue tunnel who were never there. There's still
| illegal corruption!
| choeger wrote:
| That's some hating BS right there. ITER might fail to
| produce economically viable fusion energy, but it certainly
| won't fail to produce a massive amount of scientific and
| engineering innovation.
|
| The sole fact that such a scientific undertaking can be
| done internationally, over decades, is a _great_ thing
| considering the global problems we face.
|
| Yes, ITER doesn't follow the USA economic ideology of
| "much", "cheap", and "now", but the world doesn't consist
| only of the USA and not everything works well with that
| ideology.
|
| ITER is not a PV or battery factory. It is more like the
| ISS.
| ncmncm wrote:
| ISS is an apt comparison. Its apparent purpose while the
| Shuttle was flying was to be a place the Shuttle could
| get to. What it is for now is anybody's guess. In just a
| few years it will be a celestial light show, somewhere.
|
| I have no doubt that plasma fluid physicists will learn a
| great deal from trying to get ITER lit up. Just handed
| the money, they could have learned a thousand times more,
| and maybe even achieved practical D/H-3 fusion propulsion
| for spacecraft. But that will not happen at ITER.
| choeger wrote:
| "Just handed the money", my ass. Did you ever work in
| science? How to you even think that money should be
| distributed in scientific institutions? Everyone gets a
| share based on ... what? Their degree? Number of
| publications? Consensus by committee?
|
| And for comparison, look what the ISS has brought us
| commercially: We have a fully commercial manned
| spaceflight planned for next week. That is a massive
| achievement without even considering all the scientific
| work on the station.
| ncmncm wrote:
| Handing 99% of the money to contractors for what will in
| short order be thousands of tons of radioactive slag
| contributes minimally to actual research. The developers
| of the overwhelmingly more practical FRC reactor are left
| to get by on scraps. Elsewhere in science, money is, in
| fact, being "granted" directly to scientists. This has
| gone on since long before you were born.
|
| All of the "scientific work on" ISS is done with crew
| literally pushing an "on" button on each bit of automated
| equipment running it. Experiments are forbidden to
| involve more interaction, and _also_ forbidden to operate
| without that "on" button, so the crew has something,
| anything to do.
|
| Commercial manned spaceflight could better have been
| worked without ISS. ISS's role was nothing more than a
| place to take them. Plus, a huge money sink on its own.
| It will soon fall out of the sky, and with any luck not
| hurt anybody where it crashes down.
| Chris2048 wrote:
| > All of the "scientific work on" ISS is done with crew
| literally pushing an "on" button
|
| Why is this relevant?
| naasking wrote:
| I assume he means that the crew was superfluous because
| the "on" button could be pushed remotely or automated at
| a fraction of the cost of sending people to space.
| derac wrote:
| Actually you can scale magnetic field stength or size to
| produce more power. SPARC (and later ARC) aims for the
| former with modern superconductor tech and is on track to
| potentially produce energy at Q~=11 by 2025.
| ncmncm wrote:
| I don't doubt it will produce plenty of of fast neutrons.
| Producing useful energy without destroying the most
| expensive parts of your reactor in the process is a whole
| other project. Doing it anywhere nearly as cheaply as
| overwhelmingly simpler systems whose costs are still in
| free fall is another, probably impossible project.
| stjohnswarts wrote:
| This sounds like a whole lot of speculation to me. Can you
| cite actual sources and documents that prove it?
| ncmncm wrote:
| You write like someone unfamiliar with the history of the
| other projects cited. Copious materials are readily found
| online. Read up on them. Try to identify any reason to
| imagine ITER is different. I will wait.
| dfdx wrote:
| Anecdotally, ITER was the largest of few options for a fusion
| researcher to run their experiment in a new tokamak.
| Everybody wanted to put their work into it, and as more
| features were added, the more funding it sucked up, leaving
| less money for other experiments, leading to more people
| wanting to put their experiment into ITER. Here's a
| presentation [0] that goes over why SPARC, being so much
| smaller and simpler than ITER could be more likely to
| succeed.
|
| [0] https://library.psfc.mit.edu/catalog/online_pubs/iap/iap2
| 016...
|
| This quote from the presentation summarizes it well:
|
| "The more money that's involved, the less risk people want to
| take. The less risk people want to take, the more they put
| into their designs, to make sure their subsystem is super-
| reliable. The more things they put in, the more expensive the
| project gets. The more expensive it gets, the more
| instruments the scientists want to add, because the cost is
| getting so high that they're afraid there won't be another
| opportunity later on- they figure this is the last train out
| of town. So little by little, the spacecraft becomes gilded.
| And you have these bad dreams about a spacecraft so bulky and
| so heavy it won't get off the ground- never mind the
| overblown cost."
|
| "That boils down to the higher the cost, the more you want to
| protect your investment, so the more money you put into
| lowering your risk. It becomes a vicious cycle." - Rob
| Manning, Chief spacecraft engineer, JPL
| stainforth wrote:
| The first step to correction is awareness right? Lets turn
| this tanker of human behavior away from these pitfalls.
| Gravityloss wrote:
| For NASA science probes, this cost increase and risk
| averseness spiraling is called when missions become
| "Battlestar Galactica".
| ksec wrote:
| I thought this was some joke involving Bears and Beets.
| Turns out it is an actual thing [1].
|
| > _In 1992, Dan Goldin became the NASA Administrator.
| Goldin believed in a philosophy of Faster... better...
| cheaper--i.e., he thought NASA could do more with less.
| Hence, Goldin did not support the idea of having large
| EOS platforms in space and in fact once referred to them
| as "Battlestar Galactica." He believed smaller, less
| expensive missions that could be built more quickly were
| the way to go and supported development of new programs
| that actually diverted funds from EOS._
|
| [1] https://eospso.nasa.gov/sites/default/files/eo_pdfs/P
| erspect...
| mikepurvis wrote:
| Arguably the Shuttle suffered from this too-- instead of
| being a tightly focused space truck, it needed to be able
| to do ridiculous things like fly polar missions and grab
| Soviet spy satellites right out of the air.
| mauvehaus wrote:
| Point of order: if the space shuttle were grabbing
| satellites out of the air, something has gone terribly
| wrong with both launching the satellite and the shuttle.
| mikepurvis wrote:
| I think the idea was that early spy satellites would use
| film rather than digital transmission, so it would be at
| the very least necessary to potentially grab one's _own_
| satellites.
|
| In any case, this exact question was asked here, and the
| top-rated response indicates that it's unlikely that the
| design requirement was ever meant to refer to grabbing an
| uncooperative payload:
|
| https://space.stackexchange.com/questions/41741/was-the-
| spac...
| influx wrote:
| Parent was being overly pedantic in that satellites were
| likely to be grabbed out of space and not air.
| neltnerb wrote:
| I think the joke was that the satellite isn't supposed to
| be in the "air".
| notJim wrote:
| This is an amazing observation, and something I've seen in
| many realms.
| maccam94 wrote:
| This is also why it's exciting to see the huge drop in
| satellite launch costs driven by SpaceX. Your satellite
| design is going to be much different if you have a few
| chances to launch on a $1B rocket per year, vs launching it
| for $10M anytime. Rather than one complicated reliable one,
| you might make 10 simpler ones and buy extra flights to do
| repairs if necessary.
| fragmede wrote:
| SPARC (as proposed this year, by CFS, which was founded in
| 2018) also has the benefit of 3 decades worth of
| advancement in materials science, computers, and other
| technologies over ITER, which was started sometime in the
| 1980's. Sometimes being first to market takes a long time
| and is very expensive because you first have to invent all
| of the components yourself.
|
| SpaceX's advancement is impressive, but if NASA had never
| happened, I doubt SpaceX would even exist today.
| maccam94 wrote:
| SpaceX's main innovation was that they decided to build a
| rocket that wasn't optimized for performance or
| reliability, but cost. They were willing to bear huge
| development risks to create a new price category and
| capture latent demand for cheaper launches.
| zarzavat wrote:
| I'd say what SpaceX optimises for most is iteration time.
| They have benefited hugely from an iterative development
| pattern contrasted to the waterfall pattern of NASA et
| al. Time is your biggest cost.
| tcmart14 wrote:
| I'd say yes and no. You most definitely have a point here
| as I agree that their model, or view, is different than
| NASA. However, if NASA had not happened, would even
| conceiving of a different model or target had happened?
| Not to mention just initial research into rocketry. It
| maybe could have happened without NASA, but probably with
| a severely higher initial investment.
| aaronblohowiak wrote:
| The soviets had a very strong space program and arguably
| their rocket designs have had a significant impact on
| spacex...
| Symmetry wrote:
| Super Heavy does look a lot more like an N1 than a Saturn
| V, after all.
| ksec wrote:
| Sounds like politics more than technological. Although I
| guess it is unavoidable.
| sbierwagen wrote:
| Here's a render of the completed reactor: https://www.iter.or
| g/doc/all/content/com/gallery/media/7%20-... Note human for
| size.
|
| It's all completely bespoke scientific equipment hand made
| for this project only. The cryostat will be the largest
| stainless steel vacuum vessel ever made-- all welded by hand.
|
| After welding, a substantial number of in-vessel components
| have to be installed by threading them through access ports,
| which is also quite a task:
| https://www.youtube.com/watch?v=pt70mO2nQac
| fabiospampinato wrote:
| Here's a similar picture for SPARC from wikipedia: https://
| upload.wikimedia.org/wikipedia/commons/thumb/7/74/SP...
| pas wrote:
| It still need a lot of the (same) support infrastructure.
| Plus ARC will be bigger than SPARC.
|
| That said building the first is a lot harder than scaling
| it up.
| sbierwagen wrote:
| I believe SPARC is a magnet demo, so it won't have
| tritium breeding blankets like ITER. It also has a
| shorter pulse time, 10 seconds vs 1000.
|
| (That's right. ITER, which will cost more than $65
| billion and take decades to build, can't run
| continuously!)
| ncmncm wrote:
| Nor ever produce so much as one solitary erg to flash an
| LED.
| craftinator wrote:
| You do seem to be going on quite the hatefest of Fusion,
| but continue to add nothing to the conversation,
| including sources of information. So how much energy is
| in an erg?
| ncmncm wrote:
| 3000 ergs is enough to flash an LED.
|
| When you have no turbine or any other means to extract
| power from a heat source, none gets extracted. Do you
| need a source for that?
| kwertyoowiyop wrote:
| That will become a level in an FPS game for sure.
| sgt101 wrote:
| Think cubically!
|
| A 6m device occupies 6 _6_ 6 (say) --216 m^3
|
| a 10m device occupies 10 _10_ 6 (say) -- 600 m^3
|
| The scale of volume means that you have to build a _much_
| bigger facility to put it in (in order for the electronics to
| be kept dry and for people to be able to get around it to
| keep birds off it and things.
|
| But worse - the weight. Concrete is 2400kg m ^3 so the small
| device might weigh 518 tonnes, but the bigger device is 1440
| tonnes, so moving parts of it round becomes 3 * harder, the
| floors have to be 3* stronger, the supply chain has to be 3*
| better.
|
| And then time - 3* scale, 3* engineering challenge -> many
| times more time to deliver, many more $$$ -> risk -> planning
| -> admin... the less capital at risk the less it's worth
| spending on avoiding the risk.. the less the overhead of the
| project is.
|
| FWIW ITER is a science experiment - it's designed to find out
| more about fusion and that data will be very valuable for
| future reactor designs.
| causality0 wrote:
| Are those calculations of net gain referring to the total
| energy generated, or the amount we can realistically capture
| and put to use?
| ncmncm wrote:
| The amount of this we can realistically put to use is, always
| and forever, _exactly zero_.
|
| The only useful outcome of any of this work is a generation
| of plasma-fluid physicists with practical experience. Pray we
| can find them something useful to do when the whole
| enterprise finally collapses.
| Kelteseth wrote:
| Huh, I heard the same (tinfoil) argument about climate
| change, that all scientist make up the crisis to keep their
| jobs/funding.
| ncmncm wrote:
| Scientists are not the ones making the big bucks on
| fusion demonstrator construction. But, obviously,
| somebody is. Are. Every cent of overrun goes into a
| pocket. None of it evaporates.
| liamwire wrote:
| You keep making these assertions, failing to back them up
| with anything other than hand-waving in the direction of
| entirely unrelated programs. You then respond to requests
| for citations, or even just an elaboration, with the near-
| verbatim 'do your own research.'
|
| Chiefly, how does that further the conversation? More
| pointedly, why should we listen to you?
|
| Credentialism in this arena is valid, and what I currently
| see are multiple subject matter experts, albeit with a
| bias/incentive towards believing in themselves, versus you.
| Please substantiate your claims, or word them more
| carefully as to reflect them being conjecture.
| tsimionescu wrote:
| There are still fundamental problems with fusion reactors that
| are unlikely to make them economically viable, or even carbon
| neutral.
|
| Most notably, the extreme temperatures, hydrogen pumping, and
| high-energy neutron bombardment mean that, even with liquid
| metal blankets, the reactors will very quickly become brittle,
| probably not lasting more than a year or two. Since neutron
| bombardment also turns any material radioactive, not only do
| you need to tear down your fusion plant (or at least the
| expensive reactor part of it) every few years, but you have to
| do it with radiation-resistant robots, as human workers can't
| get close to the reactor after it's been operating for a while.
|
| https://thebulletin.org/fusion-energy-nuclear-fusion/
| maccam94 wrote:
| CFS has plans for swappable vacuum chambers (1 year lifespan)
| and the liquid blanket will protect the magnets for a 10 year
| lifespan.
|
| This talk by the MIT Nuclear Science department head explains
| the whole rationale behind ARC/SPARC, and this timestamp is
| where he starts talking about maintenance and the neutron
| blanket (5 minutes later):
| https://www.youtube.com/watch?v=KkpqA8yG9T4&t=2400s
| dsign wrote:
| > Since neutron bombardment also turns any material
| radioactive, not only do you need to tear down your fusion
| plant (or at least the expensive reactor part of it) every
| few years, but you have to do it with radiation-resistant
| robots, as human workers can't get close to the reactor after
| it's been operating for a while.
|
| I bought a new screen cover yesterday for my phone. It came
| with a full mounting kit that I discarded after the ten
| minutes that took me to place the cover. The same kit could
| have been used to mount at least a hundred covers. The small
| slice of civilization I'm part of is extremely wasteful!
|
| But, let's analyze that waste. First, energy went into
| collecting and transporting those materials, plus collateral
| environmental degradation. Now, energy will be spent
| collecting and processing my waste, and if it can't be
| recycled, it will end up also provoking collateral damage.
|
| But, if we had infinite cheap energy, recycling all of it
| would be a no-brainier. Even recycling materials contaminated
| by radiation would be easy; after all, we already do that to
| refine fission fuel.
|
| Economic incentives? Those are trivial to legislate, absent
| the environmental cost and with a promise of green-house
| gases neutrality. Heck, had we infinity cheap energy, we can
| pack, move out of planet an leave all of Earth as a bio-
| reserve.
|
| In other words, nuclear fusion holds the promise of being
| such a civilization game-changer, that the question of "is it
| better than solar in the next ten to thirty years?" is moot.
| With that said, the next ten to thirty years will be vital to
| attenuate climate change, so nuclear fusion should not be
| used as a deterrent for other climate investments we can do
| today.
| tsimionescu wrote:
| You're assuming that the plant will produce more than
| enough energy in one year to power itself, power the
| country, and power the recycling effort. This assumption is
| based on nothing - current fusion dreams aren't even close
| to that kind of power generation.
| bell-cot wrote:
| Not an expert, but... "Net gain" seems to be the "give us
| enough $Billions and years and we'll find it" holy grail of
| fusion power. Vs. a $4 Casio calculator I can buy on Amazon
| today includes a zero-maintenance solar cell that is good for
| "net gain, plus useful work". Large-scale solar and wind power
| are already real-world at commercial scale, with costs per MW-h
| that pretty much beat every alternative. (
| https://en.wikipedia.org/wiki/Cost_of_electricity_by_source )
| Old-type nuclear (fission) energy has a horrible "what was
| promised, vs. what was delivered" record.
|
| Maybe your equations and power laws are right, and a "big
| enough" tokamak would be a competitive source of power. But
| then there are the details, like "big enough will cost $25
| Trillion". Followed by delays, cost overruns, etc.
|
| I'm thinking that a rational, non-expert taxpayer would say,
| "This fusion thing is a hundred times worse than NASA's Senate
| Launch System. Stop wasting my money on it NOW, and let
| gullible investors waste theirs instead."
| ArtWomb wrote:
| Delay in fusion progress seems to mirror HTS design
| difficulties. A brittle ceramic, in a punishing maelstrom ;)
|
| VIPER: an industrially scalable high-current high-temperature
| superconductor cable
|
| https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0
| vmception wrote:
| This is the best synopsis I've ever seen about it, but the
| skepticism comes from the lack of results
|
| A whole generation heard about it in school decades ago.
| Multiple generations by now, even. Its right up there with
| battery/energy-storage technologies. Headline after headline,
| enrapturing a newer and newer idealist set of people to quickly
| become disillusioned. People just get tired of it.
|
| But I'm glad to understand whats going on behind the scenes
| now. I'll pay attention. Looks like a real sleeper.
| yboris wrote:
| A march 2019 talk by Dr. Dennis Whyte of MIT working on SPARC
| https://www.psfc.mit.edu/sparc
|
| https://www.youtube.com/watch?v=rY6U4wB-oYM
| mchusma wrote:
| You are right, people who flippantly dismiss fusion just don't
| understand it.
|
| -Fusion has made consistent improvement, roughly in line with
| expectations for the level of investment (20 years away
| predictions were considering if we invested massively, which we
| did not).
|
| - Fusion is in theory something that could give us true energy
| abundance. Want to just desalinate water like crazy? Want to
| extract gigatons of carbon? Working fusion enables these to
| happen woth existing technologies.
|
| I like to think of solar, batteries, fission, and wind as
| compelling ways to go mostly carbon free and lower energy costs
| about 2x over the next 20 years or so.
|
| Fusion is what reduces energy cost potentially another 10x,
| which really changes the game for lots of things. Exciting
| stuff. Kudos to this team.
| baryphonic wrote:
| I'd add the sentiment of GP that this particular team also
| seems to have something special. I've been following them for
| a while as well, and they've impressed me by meeting self-
| imposed deadlines for project milestones (like this magnet
| experiment), being quite ingenious in designing economical
| components (the design of their original superconductor is
| quite simple but brilliant), and just having a no-BS
| approach.
| DrNuke wrote:
| The fusion equivalent of Ballmer's infamous "developers
| developers developers" line is "materials materials
| materials"... and we're getting there quickly!
| pfdietz wrote:
| And materials may not be the biggest problem! That should
| be "RAMI RAMI RAMI" (Reliability Availability
| Maintainability Inspectability).
|
| Paper studies of fusion reactor designs given an
| availability figure, but this is mere aspiration, chosen
| because that number is necessary, not because it known to
| be achievable. The few actual studies of how available a
| fusion power plant would be (using MTBF and MTTR figures
| from related technologies) have come to very troubling
| conclusions: the plant may be operating just a few percent
| of the time. Getting fusion technology to the point where
| working reactors aren't perpetually down for repair is even
| more important than developing materials tolerating higher
| neutron displacements-per-atom (because it's hard to do the
| latter without the former). This requires building an
| experience base with all the kinds of things that will go
| into a fusion reactor. It also argues for making fusion
| reactors as small as possible (so there are fewer things to
| break); this is probably the best argument for these small
| high field devices (but an even better argument for high-
| beta plasma configurations).
| pfdietz wrote:
| > Fusion is what reduces energy cost potentially another 10x
|
| How did you arrive at that conclusion?
| godelski wrote:
| Responding for the parent. They are basically making
| predictions with S curves. Technology often starts out as
| really expensive but after awhile gets super cheap,
| following what appears to be an exponential curve (bottom
| of the S), before it levels off (top of the S). Yeah, look
| more like an integral sign or sigmoid.
|
| But with fusion the endless claims of "too cheap to meter"
| are because how much energy there is in a fusion reaction.
| [0] We know that fission produces a lot of energy (but is
| expensive) but fusion produces significantly more. It also
| doesn't have the radiation drawbacks and so it is expected
| to follow the S curve (fission did initially but things
| changed. This is part of why France has so much nuclear).
|
| So if (big if) fusion does follow this S curve (which there
| are good reasons to expect it to) then it could provide a
| very cheap and sustainable energy source. Yes, it is a bet,
| but every technology is. We won't know until we spend
| significant time and money into researching it. But
| honestly, a few billion dollars isn't that crazy for the
| potential upsides. We've spent that money on far greater
| risks with lower payout. Despite what the OP said, the
| money for ITER does not require international
| collaboration. Any rich country could do it themselves.
|
| [0] (Fission and fusion can yield energy graph)
| http://hyperphysics.phy-
| astr.gsu.edu/hbase/NucEne/nucbin.htm...
| brazzledazzle wrote:
| If we got to the point where cost wasn't a factor would
| the carbon footprint be extremely low? I assume at some
| point we'll be unable to ignore climate change and our
| survival will depended on minimizing it using large
| amounts of energy from a source that doesn't have a high
| carbon footprint.
| Terr_ wrote:
| If only ~30% of CO2 emissions are from power-plants (at
| least in the US, probably higher globally considering
| developing nations) then replacing those installations
| with fusion won't directly zero things out...
|
| ... But if "cost wasn't a factor" then we could just
| simply dedicate the electrical output of fusion plants to
| brute-force CO2 out of the air.
| parineum wrote:
| If fusion drives electricity prices into the ground,
| transportation is going to rapidly go electric.
| ben_w wrote:
| PV is already driving electricity prices into the ground,
| the limiting factor right now is that batteries are
| expensive enough that long-term savings aren't enough to
| overcome the sticker-price shock at the point of sale.
| aaronblohowiak wrote:
| Yes. The reactor could more than pull out the carbon
| equivalent to its manufacture and then many many times
| more.
| godelski wrote:
| If cost wasn't a factor to any energy technology then you
| could probably negate its carbon footprint because you
| could use that electricity to cheaply pull carbon from
| the air.
|
| But there are other environmental impacts. Fusion, even
| compared to fission, has an extremely small footprint
| (per megawatt). Its fuel is easily available (isotopes of
| hydrogen). It does require some pretty advanced magnets
| though, so it will contribute to the strip mining that we
| do for rare earth materials (though this applies to all
| energy forms, including solar and wind). I don't have
| numbers to say if a fusion reactor would use less total
| rare earth metals per megawatt compared to something like
| solar or wind.
|
| One thing to note though. Once we get sustainable fusion
| reactors, it will still take a bit for that cost to come
| down significantly. That usually takes 10-20 years. This
| is a pretty common pattern. We've seen it from the price
| of laptops and cellphones to the price of solar panels.
| stjohnswarts wrote:
| Probably counting in the cost of unlimited global warming
| and all the damage it will do if we don't stop it, which we
| won't if current efforts are par for the course.
| [deleted]
| pfdietz wrote:
| That would make sense if he's comparing only against
| fossil fuels. But what was written was:
|
| > I like to think of solar, batteries, fission, and wind
| as compelling ways to go mostly carbon free and lower
| energy costs about 2x over the next 20 years or so.
|
| > Fusion is what reduces energy cost potentially another
| 10x, which really changes the game for lots of things.
| Exciting stuff. Kudos to this team.
|
| If the 10x is from avoiding fossil fuels, why does fusion
| get that credit, but the other non-fossil sources don't?
| Nevermark wrote:
| > which we won't if current efforts are par for the
| course.
|
| Because while renewable energy production is increasing
| rapidly, it is nowhere where we need it to cancel fossil
| fuels.
|
| Nothing will be soon enough. That would have been now or
| ten years ago.
|
| But anything that gets us there sooner will reduce the
| damage we have done, and fingers crossed, allow us to
| start undoing it.
| olau wrote:
| If you have a cheap means to an end or an expensive one,
| and you have limited funding because of politics, you
| will want to pour all your money into scaling the cheap
| means - then you'll get there much, much faster.
|
| I live close to a wind turbine factory. They could easily
| have scaled production multiple times over the past five
| years. The only reason they didn't is funding, in fact
| during that period they at some point cut production when
| subsidies were cut.
|
| I think it's getting to a point now where subsidies are
| not needed. But still, if you're talking about speeding
| up the process, you can just provide a little extra
| funding and get big results.
| ncmncm wrote:
| Anybody looking at numbers sees fusion never, ever
| producing so much as a single erg of commercially viable
| energy. So, anybody saying otherwise is simply making it
| up.
| JohnJamesRambo wrote:
| The sun does pretty well.
| wiz21c wrote:
| Except we didn't need to invest money in it...
| tcmart14 wrote:
| And neither did any other invention until they reached a
| certain scale, price point or level of sophistication.
| The counter to your comment would be, fusion is still
| very much in the R&D phase. As being in the R&D phase
| like so many other products were at one time, of course
| it has not met your expectation. But neither did
| Airplanes after the first flight.
| craftinator wrote:
| > So, anybody saying otherwise is simply making it up.
|
| You do see the irony of embedding this statement in a
| comment full of generalization and hyperbole, and lacking
| any evidence or credible sources, right? I genuinely
| laughed until I realized it may not have been intended as
| a joke.
| vajrabum wrote:
| What numbers are those? Or perhaps you even have a
| citation from work done on the topic by reputable
| physicists?
| tuatoru wrote:
| Yeah, really, how?
|
| Fusion power plants still need land, buildings, generators,
| switchyards, wire, own power consumption, environmental
| impact reports, planning permits, regulations, inspections,
| and all the rest. And they need exotic materials and weird
| engineering in their construction.
|
| Really: how _does_ fusion get us to ~1% (correction: ~5%)
| of current power prices?
|
| I've never seen a convincing explanation. Usually it's bare
| assertion. Infrequently it's handwavium/unobtanium.
| AnthonyMouse wrote:
| One of the big problems with existing power plants is
| that you have to build them near where people are. So
| then land is expensive and you get a bunch of regulations
| because people are worried about what's happening in
| their back yard.
|
| If you could hypothetically build a fusion plant that
| would generate several times more power than existing
| fission reactors at a similar construction cost, you
| would have so much power you wouldn't have to worry much
| about transmission losses. At which point you could put
| it in the middle of nowhere without those constraints and
| make it actually less expensive for several times more
| power.
|
| Then for cities power gets cheaper, but for anything that
| can be built out in the middle of nowhere near the
| reactor, power gets _a lot_ cheaper.
| regularfry wrote:
| > One of the big problems with existing power plants is
| that you have to build them near where people are.
|
| I don't know how it works in the US, but this is notably
| not true in the UK and Europe. Gas plants are
| comparatively small and nestled in, but big coal (to a
| limited degree) and particularly fission plants are
| frequently in the middle of nowhere. They're somewhere
| near a village that can supply a workforce, but siting
| concerns for nukes were more based on making sure any
| criticality excitement could be shared with neighbours
| across whatever nearby border was handy than putting them
| anywhere near cities.
| tuatoru wrote:
| How is that reasoning specific to fusion?
|
| Unless fusion power is dramatically more efficient than
| other thermal plants, like 99.9%, your bigger plant will
| still need massive heat removal structures and systems,
| which means siting them near water. All the good spots
| are already taken.
|
| Alternatively you can use truly massive air heat transfer
| structures, driving up your construction costs again.
|
| I neglected to mention finance costs also. With an
| untried technology the rate of return demanded is going
| to be very high, further driving up project costs.
| [deleted]
| AnthonyMouse wrote:
| > How is that reasoning specific to fusion?
|
| A major cost of the most utilized existing power plants
| (coal and natural gas) is fuel. If you build a natural
| gas plant which is twice as big so that you can put it
| out where the land is cheaper and eat the transmission
| losses, now you need twice as much natural gas.
|
| Renewables don't need fuel but their construction cost is
| fully linear, you get no economies of scale. If you want
| twice as many solar panels then you need twice as much
| land. If you want to double the size of your fusion
| reactor, you build an eight story building instead of a
| four story building on the same piece of land.
|
| > Unless fusion power is dramatically more efficient than
| other thermal plants, like 99.9%, your bigger plant will
| still need massive heat removal structures and systems,
| which means siting them near water. All the good spots
| are already taken.
|
| An obvious solution is to build them out in the ocean.
| Then you have plenty of water and you're still not near
| anything.
|
| And the good spots _near population centers_ are already
| taken. Some lake a hundred miles from any city won 't be.
|
| > I neglected to mention finance costs also. With an
| untried technology the rate of return demanded is going
| to be very high, further driving up project costs.
|
| That's only true for the first one. If it's
| hypothetically ten times more power for the same money,
| that'll get one built even at a high interest rate. Then
| once you have it running it's proven technology.
| tuatoru wrote:
| > A major cost of the most utilized existing power plants
| (coal and natural gas) is fuel.
|
| Coal is dead. The competition is PV, and to a lesser
| extent wind.
|
| > Renewables don't need fuel but their construction cost
| is fully linear, you get no economies of scale. If you
| want twice as many solar panels then you need twice as
| much land.
|
| Yes, and you use odd bits of land close to consumption
| sites, many of which will have simultaneous use for other
| purposes. Edit: the linearity is an advantage in that it
| enables mass production, and gets the benefit of the
| manufacturing learning curve. So your suggestion of
| overbuilding on cheap land a long way away from cities
| applies even more to PV.
|
| > If you want to double the size of your fusion reactor,
| you build an eight story building instead of a four story
| building on the same piece of land.
|
| Quadrupling your construction costs. Edit: mainly in the
| finance cost of the time taken.
|
| Also, making your generators much bigger than current
| practise increases project risk and therfore cost.
|
| > An obvious solution is to build them out in the ocean.
|
| Quadrupling your construction costs again, and decreasing
| reliability, capacity factor and productive lifetime.
| Seawater is nasty stuff.
|
| > And the good spots near population centers are already
| taken. Some big lake a hundred miles from any city won't
| be.
|
| It will be used for productive farmland, though. Again,
| why aren't fission or CCGT plants being built in those
| places? How is fusion different?
|
| > [High finance cost is] only true for the first one. If
| it's hypothetically ten times more power for the same
| money, that'll get one built even at a high interest
| rate. Then once you have it running it's proven
| technology.
|
| It's about time to cashflow for utility finance types,
| and they also tend to want a longer track record than "it
| worked once". The linearity/modularity of wind and PV is
| an advantage in the time to cashflow aspect.
|
| Edit: I haven't so far seen anything significant in your
| replies that doesn't also apply to fission. Utilty
| project financiers are hard-headed; they'll finance
| fission if it makes them enough money soon enough.
|
| You are fiddling around the edges rather than
| demonstrating an order of magnitude cost reduction from
| PV.
| AnthonyMouse wrote:
| > Coal is dead. The competition is PV, and to a lesser
| extent wind.
|
| Coal is dying but it's still ~20% of US generation. The
| natural gas share of US generation has gone _up_.
|
| > Yes, and you use odd bits of land close to consumption
| sites, many of which will have simultaneous use for other
| purposes.
|
| Until you run out of those and then your costs increase
| _worse than_ linearly because you have to start using
| more expensive land.
|
| > the linearity is an advantage in that it enables mass
| production, and gets the benefit of the manufacturing
| learning curve.
|
| Anything you're going to use for a large fraction of the
| power grid is going to be mass produced.
|
| > Quadrupling your construction costs.
|
| This is the opposite of how economies of scale work. If
| you make something bigger, the variable costs scale
| linearly and the fixed costs stay the same but are
| amortized over more units.
|
| > Also, making your generators much bigger than current
| practise increases project risk and therfore cost.
|
| This is no different than needing twice as many turbines
| to generate twice as much power. It's a variable cost,
| offset by you getting twice as much power without
| increasing your fixed costs.
|
| > Quadrupling your construction costs again, and
| decreasing reliability, capacity factor and productive
| lifetime.
|
| You keep saying "quadrupling your construction costs"
| without evidence. We build oil platforms in the ocean on
| a regular basis. They cost some tens of millions of
| dollars. Existing fission reactors cost some billions of
| dollars. The difference from being on the ocean is
| evidently not the dominant cost. And then you don't have
| to pay for land.
|
| > Seawater is nasty stuff.
|
| Many existing reactors are situated on coastlines and
| cooled by seawater. It's not some kind of insurmountable
| problem.
|
| > It will be used for productive farmland, though.
|
| The price of "productive farmland" compared to the price
| of land near a city is multiple orders of magnitude less,
| and high density power generation doesn't need that much
| land.
|
| > Again, why aren't fission or CCGT plants being built in
| those places? How is fusion different?
|
| New fission reactors largely aren't being built at all
| because of regulatory suppression. CCGT plants can't
| afford to spend fuel generating power which is then lost
| to long distance transmission.
|
| > It's about time to cashflow for utility finance types,
| and they also tend to want a longer track record than "it
| worked once".
|
| If it worked once but is now generating ten times more
| power per unit of investment capital than any of the
| alternatives then investors would be lining up, and may
| not even be needed because the plant operator could use
| revenues from selling such a large amount of electricity
| to build more plants with.
| tuatoru wrote:
| Here, look: take case 11 from this study by Sargent and
| Lundy[1](PDF): an AP1000 fission reactor, 2.156GW,
| $6041/kW, swap out the fission reactor for fusion
| generation at $0, and show us how to get to $176/kW (a
| tenth the per-kW price of a small-scale PV plant with
| battery storage, case 25).
|
| Also note the construction timetables: 72 months vs 18
| months for PV.
|
| 1. EIA 2020, Capital Cost and Performance Estimates for
| Utility Scale Power Generating Technologies: https://www.
| eia.gov/analysis/studies/powerplants/capitalcost...
| tsimionescu wrote:
| > This is the opposite of how economies of scale work. If
| you make something bigger, the variable costs scale
| linearly and the fixed costs stay the same but are
| amortized over more units.
|
| That's not how construction works. Past some small scale,
| construction cost scales quadratically or worse with
| size. Building a 100m tall sky scraper is not 10 times as
| expensive as building a 10m tall 3-story house - it is at
| least a hundred times more. The only reason why it's
| sometimes worth it is in ultra-high land-cost areas, such
| as Manhattan. But you'll never see sky scrapers outside
| city centers, because construction costs scale horribly
| with size, even for simple structures. Building a fusion
| chamber twice the size of ITER would likely be a new 50
| to 100 year research project.
|
| > You keep saying "quadrupling your construction costs"
| without evidence. We build oil platforms in the ocean on
| a regular basis. They cost some tens of millions of
| dollars. Existing fission reactors cost some billions of
| dollars. The difference from being on the ocean is
| evidently not the dominant cost. And then you don't have
| to pay for land.
|
| Is anyone building fission reactors, or any kind of huge
| concrete building out in the ocean at all? Extracting oil
| from the ocean is many times more expensive than
| extracting oil on land. I have no idea why you even
| imagine that it's possible at all to construct a nuclear
| power plant out in the ocean. There is certainly no
| precedent for anything even close to that.
| belorn wrote:
| > Is anyone building fission reactors, or any kind of
| huge concrete building out in the ocean at all?
|
| Yes, they are and it is a huge political issue in nearby
| countries.
|
| https://en.wikipedia.org/wiki/Russian_floating_nuclear_po
| wer...
| AnthonyMouse wrote:
| > Building a 100m tall sky scraper is not 10 times as
| expensive as building a 10m tall 3-story house - it is at
| least a hundred times more.
|
| Most of your cost difference is that a commercial
| building isn't just taller than a house, it's also wider.
| Instead of taking up a third of the lot, it uses the
| whole thing, and then has 30 times more interior space
| despite being only 10 times taller. They're also built to
| commercial building standards which are more expensive to
| meet.
|
| The costs start getting non-linear when you get into
| extremely tall buildings that pose special engineering
| challenges, but nobody is talking about building a fusion
| reactor into a skyscraper.
|
| > I have no idea why you even imagine that it's possible
| at all to construct a nuclear power plant out in the
| ocean. There is certainly no precedent for anything even
| close to that.
|
| Nuclear submarines survive the ocean just fine.
| ant6n wrote:
| Again this assumes fusion power will be cheap. But in
| reality it may cost about as much as (fission) nuclear
| power. So yes it may help with making energy production
| carbon-free (together with solar, wind, hydro), but it
| won't necessarily create a some sort of energy abundance.
| AnthonyMouse wrote:
| The theory isn't that the cost will be low, it's that the
| output will be high. If it costs the same amount as a
| fission reactor but produces ten times more power, that's
| lower cost per MW than anything on the market. Even if it
| costs more than fission, it could be competitive as long
| as the more it costs is less than the more it outputs.
| bildung wrote:
| But how should that gain in energy output be possible
| without making the whole system huge, too? The heat
| generating part of a nuclear power station only makes up
| a small fraction, most of the material is for
| transforming the heat to electricity and to shield off
| radiation. If you want to process more heat, you need
| more infrastructure to do so.
| jabl wrote:
| But why would a fusion reactor produce 10 times more
| power than a fission reactor of the same cost? A fission
| reactor is, comparatively, very simple. Just a steel
| cylinder filled with fuel and control rods. No
| superconducting magnets, no zillion degree plasma to
| contain and control, low neutron field (as long as we're
| comparing to D-T fusion). Also heat transfer is much more
| efficient, enabling high power density, since you pump
| coolant through the entire reactor vessel instead of just
| the outer edges.
| godelski wrote:
| Theoretically? Pure brute force. Fusion just generates
| that much electricity that it has the potential to be
| insanely profitable. There's a lot of ifs, but there's a
| good reason to bet big on it.
| tuatoru wrote:
| Please explain how it generates that much electricity
| that cheaply.
|
| Direct conversion is theoretically about 60% thermally
| efficient, on par with combined cycle gas generators.
| godelski wrote:
| > Please explain how it generates that much electricity
|
| This is the non-theoretical part
|
| > that cheaply.
|
| This is the theoretical part. I think a lot of people are
| misinterpreting my comment. I have absolutely no idea if
| it can be done that cheaply. But I can say for a fact
| that the yield of energy is massive. The question is if
| it can be done cheaply. That's the bet. The question is
| if you want to take that bet. You have to make similar
| bets on tons of technologies. It usually takes 10-20
| years after something is made till it starts to follow
| the S curve and become cheap. Even solar and wind
| followed this.
| tsimionescu wrote:
| People often make the mistake of looking at the reaction
| energy of fusion, and comparing that with fission or
| burning fossil fuels.
|
| But the majority of the reaction energy is carried away
| by high-speed neutrons, which are pure waste - they can't
| be captured by magnetic fields, they are heavy and
| penetrate almost any material, leaving holes behind that
| make the structure brittle, and when they do get
| absorbed, they make the atom that absorbed them unstable,
| turning the material radioactive.
|
| So, at least as long as we use neutri-producing fusion
| (and any realistic fusion reactor has to) the actually
| usable energy is not that impressive compared to fission.
| pjerem wrote:
| That's about the same infrastructure than a nuclear
| fission reactor. And nuclear electricity is already
| pretty cheap.
|
| I don't know how it costs in US, but in France, fully
| charging a Model 3 costs about ~5EUR at night. That's not
| 10x cheaper than gas but that's a lot cheaper.
| bildung wrote:
| Retail electricity prices in France are EUR0,13/kWh, so
| not _that_ cheap (EUR0,18 /kWh pre pandemic).
|
| https://www.statista.com/statistics/418087/electricity-
| price...
|
| This doesn't matter, though, because France doesn't need
| many nukes anymore, therefore doesn't subsidizes new
| plants anymore. One new plant is built in France, and it
| already is hellishly expensive: "As of 2020 the project
| is more than five times over budget and years behind
| schedule. Various safety problems have been raised,
| including weakness in the steel used in the reactor." htt
| ps://en.wikipedia.org/wiki/Flamanville_Nuclear_Power_Plan
| ...
| olau wrote:
| There are two problems with this reasoning. First, you
| are comparing the cost of written-off plants, for a
| technology that has huge upfront costs and much lower
| fuel costs.
|
| Fission is not cheap if you build a new nuclear plant,
| not in the Western world. That's why almost no nuclear
| plants are being build. Making a safe plant is just
| really, really complicated.
|
| Second, this specific argument can be used to see why
| fusion is a pipe dream. The primary competitor to fusion
| is fission. And the fuel costs of fission are pretty low,
| as you just said. So fusion will not be competitive
| unless you can built them around the same price as
| fission plants.
|
| Someone else in this thread talked about S curves. Well,
| those kind of S curves happen for tech that gets produced
| in larger quantities, where it is economical to spend
| engineering resources making the production of the tech
| cheaper.
| pjerem wrote:
| Maybe I'm wrong but fission also don't need extreme
| cooling utilities. And fission seems to be way more
| secure than fusion. So, while I do agree on the << new
| tech >> costs, I'm pretty confident we'll be able to
| build this plants anywhere in the world and not only near
| rivers.
|
| But maybe I'm too optimistic :)
| phreeza wrote:
| I think you mixed up fission and fusion there.
| Regardless, a fusion reactor will need similar amount of
| cooling infrastructure if you want to output a similar
| amount of electricity.
| qPM9l3XJrF wrote:
| "Fusion is in theory something that could give us true energy
| abundance."
|
| What does fusion give us that existing nuclear power plant
| tech doesn't?
| nobody9999 wrote:
| >What does fusion give us that existing nuclear power plant
| tech doesn't?
|
| The energy generated per unit mass in a fusion reaction is
| ~9 times that generated in a fission reaction[0]:
| Considering the mass of the four protons/hydrogen
| nuclei (4.029106u) and the mass of the Helium
| produced (4.002603u) we get a mass difference of
| 0.026503u or 24.69MeV. So it is easy to see that
| fusion reactions give out more energy per reaction.
| However, the energy per unit mass is more relevant.
| This is 0.7MeV for fission and 6.2MeV for fusion so
| it is obvious that fusion is the more effective
| nuclear reaction.
|
| Which leads to a great deal of confusion on my part as to
| why we're not spending _enormous_ amounts of money on
| Fusion R &D. Given the potential of the technology, you'd
| think we'd have long ago decided to spend whatever was
| necessary to commercialize hydrogen fusion as a power
| generation mechanism.
|
| The phrase "electricity too cheap to meter" is likely
| somewhat hyperbolic, but in comparison to pretty much any
| other mechanism fusion is enormously more productive and
| efficient.
|
| [0] https://www.physlink.com/education/askexperts/ae534.cfm
| drexlspivey wrote:
| The reactor can't meltdown and contaminate the whole
| planet. Also there is no radioactive waste
| ziotom78 wrote:
| Well, there is some radioactive waste [1], but its decay
| time is far smaller and is thus far easier to handle.
| (Moreover, there is a larger choice of elements.)
|
| [1] https://en.wikipedia.org/wiki/Fusion_power#Radioactiv
| e_waste
| el_nahual wrote:
| Aren't fast decay times _harder_ to handle?
| kamaal wrote:
| >>What does fusion give us that existing nuclear power
| plant tech doesn't?
|
| Water is more abundant than Uranium?
| p0nce wrote:
| What is the downside?
| clusterfish wrote:
| Is it really limitless if both generating and consuming
| energy produces heat? Or is that too small of an effect even
| despite the heat inefficiency of fusion?
| xyzzyz wrote:
| Earth gets multiple orders of magnitude more heat from the
| Sun than humans can ever hope to generate. In concrete
| terms, Earths gets 153 PW of energy in terms of solar
| radiation. It also radiates as much. In comparison,
| humanity uses something like 20 TW in total (that includes
| not only electricity, but also transportation etc). So, we
| could increase our energy use 100 times, and still be only
| around 1% of what we get from the Sun.
| kongin wrote:
| So that's between 150 and 250 years with the 2.5% energy
| consumption grows, then that much again for us to produce
| more energy than the sun shines on Earth.
|
| https://en.wikipedia.org/wiki/World_energy_supply_and_con
| sum...
| xyzzyz wrote:
| Yes, and with 2.5% energy consumption growth, in only
| 2500 years, we'll consume entire power output Milky Way
| galaxy.
|
| Extrapolating exponential growth over long timescales
| leads to silly results.
| [deleted]
| phreeza wrote:
| > I like to think of solar, batteries, fission, and wind as
| compelling ways to go mostly carbon free and lower energy
| costs about 2x over the next 20 years or so.
|
| > Fusion is what reduces energy cost potentially another 10x,
| which really changes the game for lots of things. Exciting
| stuff. Kudos to this team.
|
| Citation needed... If the fusion reactors end up needing tape
| of room temperature superconductors to keep their confinement
| going, and they degrade rapidly due to neutron radiation, I
| could easily see solar being cheaper in the long run. I'm not
| saying this is exactly what will happen, but I have never
| seen compelling proof that fusion will really be so cheap in
| terms of capex or opex per Watt.
| tsimionescu wrote:
| > Fusion is in theory something that could give us true
| energy abundance.
|
| The biggest problem is the 'in theory' part. With current
| plausible designs, the vast majority of the fusion reaction's
| energy is carried away by high-powered neutrons, which are
| entirely waste products.
| ajdegol wrote:
| The neutrons are what we will extract energy from, the
| alpha particles continue heating the plasma.
| tsimionescu wrote:
| Some do, but most of them escape from the plasma,
| carrying away energy, and need to be captured by the
| neutron blanket. This amounts to a whopping 80% of the
| reaction energy.
|
| The real dream are fusion reactions which don't produce
| neutrons, such as H1+H1 or much more realistically,
| H2+B11 (though still many times harder than H2+H3).
| xbmcuser wrote:
| Yeah we need Fusion if we want to put back the carbon into
| the ground as the rest can mostly help us bring down new
| carbon use but Fusion can bring down the cost of carbon
| capture to actually reverse global warming as well. So far
| the world is just looking at mitigating or slowing it down
| only which is simply put not enough.
| pfdietz wrote:
| > we need Fusion if we want to put back the carbon into the
| ground
|
| There is nothing about fusion that makes it essential for
| putting carbon back into the ground.
| nico_h wrote:
| This is the kind of comment that make me really hope that we
| can kill energy intensive _coins before that happens.
|
| I mean if we 10x the waste heat that could be produced by
| asics solely for the purpose of mining _coins, it could be
| enough to create a mini climate.
| singularity2001 wrote:
| don't solar panel prices half every five years (similar to
| moores law modified)? fusion would need to speed up then to
| be competitive with the solar revolution
| baq wrote:
| solar needs sun and massive batteries to handle base load.
| fusion base load + solar + wind + batteries sounds like the
| end game.
| ben_w wrote:
| Don't forget long distance transmission in that mix: HVDC
| can be done with losses of only 3.5%/1000km, which makes
| it a cost/geopolitics issue for your night to be someone
| else's day, your winter someone else's summer.
| crubier wrote:
| The issue with long distance transmission is not
| efficiency. It is the raw amount of material needed.
|
| Feeding 100% of Europe electricity use with solar panels
| in North Africa would required many years (!) of the
| world's current aluminium production, just to build the
| transmission cables.
|
| Do the calculation, you'll see.
|
| Long distance power lines do not work to transmit massive
| amount if electricity on a global scale.
| ben_w wrote:
| I'm not sure why you imagine that building this at full-
| grid power levels might take less than a decade, nor why
| it might be an all-or-nothing proposition given every
| single gigawatt can be seen as as a (12GWh? I'm not sure
| but that magnitude) battery system not purchased, but
| I'll gladly do the maths.
|
| 1) HVDC designs I've seen are copper (towers use
| aluminium because it's light, IIRC)
|
| 2) http://www.necplink.com/docs/Champlain_VT_electronic/0
| 4%20L....
|
| Gives 2500mm^2 cross section for a 1 GW cable
|
| 3) WolframAlpha says Europe's electricity production is
| 410 GW: https://www.wolframalpha.com/input/?i=total+Europ
| e+electrici...
|
| Which means the total conductor cross section needed is
| ~1 million mm^2 = 1m^2. Ok, this sounds like it's going
| to be a lot.
|
| 4) Lets put a line across the Sahara to connect all the
| panels plus connections to the existing EU grid in
| Gibraltar, Athens, and Milan.
|
| It's about 3700km from Casablanca to the middle of Egypt:
| https://www.wolframalpha.com/input/?i=casablanca+to+egypt
|
| Likewise 350km for Gibraltar, 1000 km Awjilah to Athens:
| https://www.wolframalpha.com/input/?i=Awjilah+to+athens
|
| This gives a total length of about 5000km, if I spec the
| cable for 100% of EU power going through each cable,
| which is excessive as I was trying to suggest this as an
| _adjunct_ to batteries and local PV rather than a _total
| replacement_ for either: any combination (including none)
| of transmission and storage only has to cover lower
| nighttime /seasonal averages).
|
| This gives me a total volume of 5000km * 1m^2 = 5e6 m^3.
|
| 5) This is copper, worldwide production of copper is
| 14.6e6 tons/year, given the density this is indeed 1.4e6
| m^3/year and therefore multiple years at current mining.
|
| 6) Global aluminium production is 82.6 million tons/year:
| https://www.wolframalpha.com/input/?i=worldwide+aluminium
| +pr...
|
| Aluminium is 60% the conductivity of copper; I assume
| that means I need the conductor to be 1/0.6 times the
| cross section? Not my field. Assuming that, I want 8.3e6
| m^3 aluminium, given the density that's 22 million tons,
| so 3 months.
|
| Edit: I forgot Milan!
|
| 7) Tataouine to Milan is about 1500 km:
| https://www.wolframalpha.com/input/?i=Tataouine+to+Milan+
|
| Therefore multiply my mass estimates by 1.3
|
| Edit 2:
|
| 410 GW is also 2-2.5 times current global PV
| installation:
| https://en.wikipedia.org/wiki/Growth_of_photovoltaics
|
| If you did put enough PV for all of Europe on top
| of/along side the Casablanca-Egypt line, the PV would
| need to be about 550m wide: http://www.wolframalpha.com/i
| nput/?i=%28410GW%2F%281kW%2Fm%5...
|
| (I only need to care about peak power in this case, not
| average, hence only the 20% efficiency factor and not
| including the additional 25% duty factor).
| dboreham wrote:
| I have a Dyson sphere to sell you..
| isoskeles wrote:
| Imagine how much Bitcoin we could mine with that kind of
| energy source...
| wsc981 wrote:
| _> Imagine how much Bitcoin we could mine with that kind of
| energy source..._
|
| Not much more nor less, since the amount of Bitcoin
| generated every 10 minutes is controlled by an algorithm
| independent on how many machines are mining.
| dodobirdlord wrote:
| Yea, but imagine how secure we could make the blockchain!
| /s
| codethief wrote:
| > Fusion is in theory something that could give us true
| energy abundance.
|
| Well, at least for a few hundred years but then:
|
| > if you plot the U.S. energy consumption in all forms from
| 1650 until now, you see a phenomenally faithful exponential
| at about 3% per year over that whole span. The situation for
| the whole world is similar. [...] the Earth has only one
| mechanism for releasing heat to space, and that's via
| (infrared) radiation. We understand the phenomenon perfectly
| well, and can predict the surface temperature of the planet
| as a function of how much energy the human race produces. The
| upshot is that at a 2.3% growth rate [in energy consumption]
| (conveniently chosen to represent a 10x increase every
| century), we would reach boiling temperature in about 400
| years. [...] And this statement is independent of technology.
| Even if we don't have a name for the energy source yet, as
| long as it obeys thermodynamics, we cook ourselves with
| perpetual energy increase.
|
| Source: https://dothemath.ucsd.edu/2012/04/economist-meets-
| physicist...
| DanielVZ wrote:
| I'd take that statement with a grain of salt. If there's
| something that COVID has taught me is that in reality
| exponential curves almost always turn into sigmoids
| wherever there are limiting factors. The key here is where
| the curve starts flattening.
|
| The same goes for infinite growth. In the close future it
| sure looks infinite, but I'd say it's infinitely hard too
| to predict what will happen in say a 100 years (a fourth of
| the time before we hit the heat death wall predicted here).
| lyaa wrote:
| The quoted argument is too simplistic and ignores feedback
| processes that would prevent reaching the catastrophic
| prediction. We can't predict 400 years so flippantly.
|
| The population will most definitely not continue to grow
| (in fact it will start to decrease slightly the more
| countries reach "developed" status), and the energy
| consumption per-capita will also stagnate. After all, there
| is a huge difference between going from living in a log
| house to a modern apartment with utilities and AC, and not
| much of a difference between one laptop and a slightly
| better one some years down the line. Also, attitudes
| towards environmental protection are changing with the
| generations so we are likely making different decisions 50
| years from now.
| f00zz wrote:
| Reminds me of those late 19th century predictions
| according to which in 50 years London would be neck-deep
| in horse poop
| ifdefdebug wrote:
| Well if we transform solar into electric then into motion
| or bound carbon, that should actually help reduce the heat
| balance?
| acchow wrote:
| But then what do you do with that motion?
|
| Eventually it all decays to heat, as per the 2nd law of
| thermodynamics
| codethief wrote:
| > into motion
|
| Kinetic energy will end up getting converted to waste
| heat nonetheless.
|
| > or bound carbon
|
| This seems hard to imagine. We're dealing with waste
| energy here, so a very high-entropy type of energy. Bound
| carbon is low-entropy, so the conversion is impossible[0]
| unless we put that entropy elsewhere.
|
| As an analogy, consider a fridge: It brings your food
| from a high-entropy (high-temperature) to a low-entropy
| (low-temperature) state but in order to do that it also
| has to produce waste heat (entropy) on the outside.
|
| [0]: https://en.wikipedia.org/wiki/Second_law_of_thermody
| namics
| regularfry wrote:
| We're not necessarily talking about a closed system,
| though. If you've got an energy supply that rounds to
| limitless, constructing planet-scale heatsinks starts to
| look tenable.
| codethief wrote:
| > We're not necessarily talking about a closed system,
| though.
|
| Short of shooting hot lava into space[0] we pretty much
| are because, once again, thermalization through radiation
| is governed by Stefan-Boltzmann's law and there's no way
| around that.
|
| [0]: https://news.ycombinator.com/item?id=28468182
| goodpoint wrote:
| Absolutely yes. Energy is captured by solar panels. They
| make a shade, obviously, and what is in their shade does
| not get heated by the sun.
|
| If you were to use 100% of solar panel energy to heat up
| something else the overall balance would be 0.
|
| Contrarily, nuclear fission/fusion that releases energy
| from its fuel, ultimately heating up the planet.
| filleokus wrote:
| Huh, that's interesting!
|
| I wonder, in a strictly thermodynamic way (ignoring CO2
| etc), how big of an impact it would have to remove all
| internal combustion engines in land-based transportation
| and power generation (coal plants).
|
| ICE's have like a 30-40% efficiency? Compared to electric
| engines 80-90%. But on the other hand, you probably consume
| quite a bit of energy producing the batteries...
| ben_w wrote:
| Per battery or overall to the planet?
|
| Per unit of storage, Wikipedia says the lifetime storage
| capacity of batteries etc. relative to energy needed to
| construct them is:
|
| Lead acid: 5 times construction energy; Vanadium redox:
| 10; LiIon: 32; Pumped hydro: 704; Compressed air: 792.
|
| I can't remember where I've seen this, but I think a unit
| of PV produces all the energy it took to manufacture
| after a month or two.
|
| If you mean overall? As a rough guide we emit about 35GT
| CO2/year which is about 9.5e12 kg carbon; burning carbon
| releases about 32MJ/kg; so about 3e20 J/year, or 9 TW, or
| 19 mW/m^2.
|
| There's more energy in the hydrogen in gases and oils,
| this is just a ballpark estimate of the thermodynamic
| output of burning that much does to directly heat the
| planet.
| hoseja wrote:
| >(infrared)
|
| How to tell an undereducated journo.
| amelius wrote:
| The thermodynamics argument would hold only for a closed
| system. If we send big blobs of lava into space, and import
| big chunks of solid rock back to Earth, then theoretically
| we should have no problem.
| jeremyjh wrote:
| > If we send big blobs of lava into space
|
| I honestly can't tell if you are joking. The energy
| expenditure to get anything into orbit would produce more
| heat than you are offsetting.
| gpm wrote:
| Depending on the design of the system, the energy could
| well be expended in orbit and not contribute to the
| heating of earth (think about designs like a space
| elevator).
|
| He's basically describing a giant air conditioner... it's
| definitely theoretically possible.
| codethief wrote:
| > it's definitely theoretically possible.
|
| In theory yes, but in practice: Not so much.
|
| Even if we put aside GP's concerns, shooting big blobs of
| lava into space would require heating up the lava/rock in
| the first place. But this process doesn't happen on its
| own (through thermalization) given the average
| temperatures on Earth, meaning that the process of moving
| waste heat (from the environment, i.e. air/ocean) to the
| lava will once again _decrease_ entropy (of the combined
| lava + air /ocean system) and you thus need to move the
| missing entropy elsewhere. (Meaning that you have to do
| work to accomplish this heat transfer / dethermalization
| and you will once again incur waste heat.)
|
| Sure, we could also try to tap the heat bath of the
| Earth's core but then we would build a deep-Earth
| elevator to transport lava and solid rock (or, say,
| water) back and forth and GP's concerns apply once more.
|
| There's another option, though: Don't build an air
| conditioning system/fridge - use thermalization with
| another (lower-temperature) system. That is, don't take
| lava (or anything that needs to be heated beyond ambient
| temperature) - "just" take rock at (Earth's) ambient
| temperature, move it to a lower-temperature $PLANET and
| then move cool rock from $PLANET back to Earth. I doubt
| this would be very efficient/fast, though.
|
| In any case, the difference between the two approaches is
| that an air conditioner (or a fridge) cools things
| _below_ ambient temperature and requires additional
| energy for that (which it will expel as waste heat),
| while the second approach "simply" moves energy from the
| heat bath that is Earth to some lower-temperature
| reservoire (i.e. $PLANET). If $PLANET and Earth were
| thermodynamically connected not just through the exchange
| of infrared radiation, this would happen by itself over
| time through thermalization.
| fouric wrote:
| This idea seems like the CICO (Calories-In, Calories-Out)
| argument, and is misleading/wrong for exactly the same
| reasons - neither the Earth+people (or even just the Earth)
| nor the human body just stock energy like that linearly.
|
| If you increase the amount of energy flowing into the human
| body, the metabolism increases as well (although almost
| never proportionally - there are many variables) to
| compensate.
|
| Similarly, it's rather unlikely that humans will continue
| to use exponentially increasing amounts of energy, unless
| we intentionally do something to effect that. Human
| population growth, which is partially driving energy
| consumption, is _not_ exponential (it would be exponential
| absent of resource constraints or cultural factors, but
| guess what - both of those are in effect rather strongly in
| the real world) - and neither is energy consumption per
| capita. For instance, from 2005 to 2020, the US gained 30M
| people[1] while keeping energy consumption roughly
| constant[2].
|
| [1] https://datacommons.org/place/country/USA [2]
| https://www.statista.com/statistics/201794/us-electricity-
| co...
| gghyslain wrote:
| You can't just look at electricity consumption. You have
| to look at total energy consumption. Including the energy
| necessary to produce the goods you consume. And that is
| increasing exponentially.
|
| In a way, the US (and Western countries) are outsourcing
| their energy consumption.
| codethief wrote:
| > Including the energy necessary to produce the goods you
| consume.
|
| Exactly, the original link I posted is more or less an
| argument against infinite economic growth.
| [deleted]
| roenxi wrote:
| If there is enough ambient energy to literally boil the
| seas then we're probably going to find it easy enough to
| leave the earth and go somewhere cooler.
| codethief wrote:
| I don't think it'll be _easy_.
|
| We would have the same (if not higher) energy consumption
| per capita on any other planet. And unless that planet is
| humongously large (which would also increase its surface-
| level gravity, thus rendering it uninhabitable), the
| relation between surface temperature and energy
| consumption will be similar[0]. Now there's only a finite
| number of planets in our solar system and leaving our
| solar system, say in the direction of Proxima Centauri
| (the star nearest to the Sun), amounts to traveling ~4.2
| light-years. At a velocity of 0.1c (which is a _lot_ -
| especially if you 're trying to move an entire
| species[1]) that means a travel time of 42 years (as seen
| from our current frame of reference). Any velocity lower
| than that and we're getting into hundreds-of-years
| territory, so we'll be needing space ships across we can
| live for generations.
|
| Also, a space ship is not that different from a planet,
| in that it also has to obey thermodynamics. So the
| surface temperature issue there is just the same. (In
| fact it's worse, since our space ship will likely be
| smaller and we also need to factor in additional waste
| energy of the space ship's propulsion engine or whatever
| we're using.)
|
| [0]: https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzma
| nn_law
|
| [1]: Or, say, half the species (or whatever amount
| necessary to make the total energy consumption on the
| planets we already inhabit drop to levels such that the
| planets' surfaces don't start to boil).
| danuker wrote:
| > So the surface temperature issue there is just the
| same.
|
| On an interstellar ship far from a star, I think you're
| more likely to freeze to death, because temperature in
| space is near zero Kelvin.
|
| Inside the solar system however, you could reflect away
| the received radiation (and heat) using mirrors.
| roenxi wrote:
| We're talking a world where humanity has enough energy on
| tap that not only _could_ it have feasibly evaporated the
| Pacific Ocean, but that it basically _has_ evaporated the
| Pacific Ocean, as a side effect of doing something else.
|
| We can barely speculate about such a world, but
| interstellar travel would not be much of a challenge with
| that sort of energy abundance. We'll find a way.
| codethief wrote:
| > but interstellar travel would not be much of a
| challenge with that sort of energy abundance.
|
| I don't think I agree.
|
| 1) The extremely high (but still finite) amount of energy
| required to evaporate the Pacific Ocean is still _much
| less_ than the _infinite_ energy you need to accelerate
| even _one single_ space traveler to the speed of light.
| Infinity is weird.
|
| Of course we won't be trying to reach the speed of light
| but the energy (and fuel) required to move half the
| species (so that the other half can stay on
| Earth/Mars/...) will still be significant.
|
| 2) My second argument was that the Stefan-Boltzmann law
| is just the same on board the space ship. And if we live
| there for generations, chances are our energy consumption
| per capita will be similar as on the planet we left, and
| so we will be running into similar issues with Stefan-
| Boltzmann's law. Sure, we can split up the passengers
| across multiple space ships and make each ship much
| bigger (to increase surface size) but not only will this
| increase the total mass and thus fuel required for the
| trip but we would probably _still_ not achieve the
| (rather high) surface area per capita ratio that we have
| on Earth.
| codethief wrote:
| Addendum to 1):
|
| Thinking a bit further, just because we can produce a
| high amount of energy that doesn't necessarily mean we
| can automatically convert it into kinetic energy for a
| space ship very well. Most propulsion systems in space
| still require expelling a propellant and conservation of
| momentum means this is unlikely to change. (Sure, one
| could imagine solar sails but the little momentum
| exchanged there won't get half of humanity to Proxima
| Centauri very fast.) So while we might have unlimited
| energy we might still be constrained by momentum
| requirements.
|
| The only way I can see to solve this conundrum would be
| producing enough propellant on board the space ship, e.g.
| (lots of) photons, using a laser. Definitely not
| impossible (especially not at these energy levels) but
| it'll be interesting to see what these propulsion systems
| will look like exactly. :)
|
| Ideally, we would of course try to use the propellant to
| also get rid of the waste heat mentioned earlier but I'm
| not sure whether this would work entropy-wise.
| Aeolun wrote:
| > The extremely high (but still finite) amount of energy
| required to evaporate the Pacific Ocean is still much
| less than the infinite energy you need to accelerate even
| one single space traveler to the speed of light.
|
| True, but how many tons of space junk can you accellerate
| to 95% of light speed for the same amount of energy?
| codethief wrote:
| Quick back-of-the-envelope calculation:
| Approx. mass of Pacific Ocean[0]: m_ocean = 7.1x1020kg
| Specific heat of water: c = 4.2kJ/(kg * K)
| Temperature of Pacific Ocean: T_1 ~ 293K
| Temperature at which water starts boiling: T_2 ~373K
|
| => Energy needed to make Pacific Ocean boil:
| E_heat = c m_ocean DT = c m_ocean (T_2 - T_1) ~ 3x1026 J
|
| On the other hand, the relativistic kinetic energy
| formula is: E_kin = (g-1) m c2,
|
| where g = 1/sqrt(1-v2/c2) = 1/sqrt(1-0.952) and m is the
| space junk's mass.
|
| Setting E_kin = E_heat therefore yields:
| => m = E_heat / [(g-1)c2) = 3x1026 J / (2.2x1016 m2/s2)]
| = 1010 kg
|
| For comparison: The mass of all of humanity combined is
| somewhere between 1011kg and 1012kg. Now those numbers do
| look somewhat comparable but:
|
| - We haven't taken into account the space ships required
| to transport everyone
|
| - E_heat was waste heat but since practically all energy
| will become waste heat at the end of the day, E_heat
| gives us a pretty good estimate of the total energy we
| will have (had) access to.
|
| All in all 0.95*c doesn't seem feasible for moving
| humanity to Proxima Centauri, given E_heat. For moving
| 1010 kg of space junk, sure, though I'm not sure what you
| were planning to do with all that space junk in the first
| place?
|
| [0]: https://en.wikipedia.org/wiki/Pacific_Ocean
| zo1 wrote:
| Not quite sure I follow. On earth we're mostly limited to
| radiation to get rid of excess heat, I understand that
| part. But on a space-ship, can we not just expel the heat
| via mass? I.e. We super-heat some dense materials and
| just shoot them out.
| codethief wrote:
| Where will you be getting all that mass from, though?
|
| > We super-heat some dense materials
|
| This won't work as you would need to put in additional
| work (leading to additional waste heat) in order for this
| process to lower ambient temperature. The only thing you
| could do is shoot stuff out that's precisely at ambient
| temperature, compare
| https://news.ycombinator.com/item?id=28471620 .
| ben_w wrote:
| I believe the two of you are talking about different
| things.
|
| The argument in the UCSD blog post linked above will
| apply to any finite system _if_ you assume exponential
| growth in power use, and exponential beats cubic for
| expansion to other worlds (I'm assuming no FTL for a
| cubic limit to expansion).
|
| Abundant power -- be it from fusion or solar or quantum
| magic -- does not actually need to guarantee eternal
| exponential growth of power use, but the absence of such
| growth would necessarily lead eventually to the absence
| of economic growth.
|
| We can still have a SciFi future without that, it will
| just look different in a way our current society can't
| properly envision (which I think is an unsurprising a
| claim to make even in the absence of the rest of this
| argument).
| veltas wrote:
| How do we know that global temp rise isn't just due to
| energy usage? I mean "does that calculation fit at all?",
| not "carbon dioxide is fake".
| jabl wrote:
| Because we know that so far humanity's energy use is so
| small that the heating effect via increased blackbody
| radiation equilibrium temperature is utterly dwarfed by
| what mainstream climate focuses on, like GHG gasses.
| chriswarbo wrote:
| It's the difference between a hand-warmer and a coat. The
| hand-warmer adds extra heat to the system (like the heat
| from burning fossil fuels). A coat doesn't add any extra
| heat, it just traps some of the heat that would otherwise
| be lost (like greenhouse gasses).
|
| Hand-warmers can keep part of the body warm for a few
| hours. Coats can keep the whole body warm for years.
| thow-58d4e8b wrote:
| Not even close.
|
| Global energy use is around 170,000 TWh/year (1). This
| includes electricity generation, as well as fuel for
| transport, burning wood for heat, etc.
|
| Heat flow from mantle is 403,000 TWh/year (2)
|
| Solar irradiance is ~1200W/m2, which adds up to massive
| 5B TWh/year.
|
| Extra radiative forcing from greenhouse gases in IPCC
| scenarios is ~3W/m2, or around 12.5M TWh/year.
|
| The radiative forcing is two orders of magnitude larger
| than our energy use.
|
| (1) https://en.wikipedia.org/wiki/World_energy_supply_and
| _consum...
|
| (2) https://www.nature.com/articles/ngeo.2007.44
| veltas wrote:
| Thanks, this is the calculation I was looking for.
| kongin wrote:
| >You are right, people who flippantly dismiss fusion just
| don't understand it.
|
| I have a couple of physics degrees, hot fusion is the energy
| of the future and it always will be. This is not a physics
| problem, this is an engineering problem and we are just not
| willing to invest enough money to solve the engineering.
| maccam94 wrote:
| Commonwealth Fusion Systems is privately funded and aiming
| to demonstrate net energy gain in 4 years. It's not like
| the lumbering ITER project.
| sgt101 wrote:
| I had a chat with Professor Whyte about this about 5 years
| ago when he was starting on this quest. The key insight
| that he emphasized to me (that I could understand!) was the
| need to deal with the engineering. He told me that compact
| magnets would facilitate construction and maintenance
| because simply they would need less space and energy to be
| physically manipulated. This, as I understood it, would
| allow for huge reductions in cost because buildings and
| components scale in cost massively as their size increases.
| Small magnets won't need a huge building, they won't need
| special vehicles to move them, they won't need cranes to
| install, they can be swapped in and out during maintenance,
| and the work can be planned and executed by small teams at
| low risk. Who really cares if a team of 5 working for a
| week have a 10% overrun - that's 2.5 person days. On the
| other hand a team of 500 working for a year -> 50 person
| years. Scale is the overhead that they are targetting.
| nobody9999 wrote:
| >I have a couple of physics degrees, hot fusion is the
| energy of the future and it always will be. This is not a
| physics problem, this is an engineering problem and we are
| just not willing to invest enough money to solve the
| engineering.
|
| You're spot on. Which makes no sense at all. Given the
| potential of commercial fusion, we should be (globally)
| spending at least several tens of billions per year on R&D.
|
| Assuming the engineering issues are solved, those hundreds
| of billions would be chump change compared to the economic
| benefits of volume of cheap, clean power.
| pontifier wrote:
| Fusion is on my plate too. I've got a design that I really need
| to test, an I've finally got the funds to begin construction.
|
| My method uses much lower magnetic fields that could be provided
| by permanent magnets, but should allow containment times on the
| order of weeks for small quantities of D-D fuel.
|
| I have more information at http://www.DDproFusion.com
| rpmisms wrote:
| I love backyard science like this. No offense intended at all,
| but it's always heartening to see the Davids fighting the
| Goliaths.
| dmix wrote:
| Looks like the video on your site is not working. At least from
| my region.
| derac wrote:
| SPARC is an amazing project. Congrats on this milestone! I am
| optimistic about SPARC and ARC. I'd love to hear legitimate
| critiques, though. I see a lot of negative comments on ITER,
| which is a very different situation. ITER will teach us a great
| deal btw, it isn't a waste of time.
| rkangel wrote:
| It's nice to see another promising avenue. The Wendelstein 7-X (a
| Stellerator) design is the other one that I'm particularly
| interested in. I believe it met its initial goals and is now in a
| multi-year refit before attempting continuous operation.
| TrainedMonkey wrote:
| This is exciting. Magnetic field strength is a key component for
| enabling magnetic confinement fusion. This is because energy gain
| and power density scales to the 3rd and 4th power with magnetic
| field strength but only ~linearly with reactor size. See
| following equations for more details:
| https://youtu.be/xJ2h3vbOag4?t=306
|
| So, why is this particular announcement exciting? There are 3
| factors:
|
| 1. This is a high temperature superconductor. I can't find any
| references, but as far as I remember the substrate they are using
| needs to be cooled to (WRONG, it was cooled to 20degK, see reply
| by MauranKilom) 60-70 degK to achieve super conductivity. Compare
| to magnets used in ITER which need to be cooled to 4degK. This is
| the difference between using relatively cheap liquid nitrogen vs
| liquid helium.
|
| 2. Field strength of 20 Tesla is significantly higher than 13
| Tesla used in ITER. Given that magnetic confinement fusion scales
| significantly better with field strength vs reactor size, this
| will enable much smaller reactor to be power positive. See
| following links for more details on ITERs magnets:
| https://www.newscientist.com/article/2280763-worlds-most-pow...
| https://www.iter.org/newsline/-/2700
|
| 3. Finally, the magnet was assembled from 16 identical
| subassemblies, each of which used mass manufactured magnetic
| tape. This is significantly cheaper and more scalable than custom
| magnet design/manufacturing used by ITER.
|
| The kicker is how 3 of the factors above interact with the cost
| of the project. Stronger magnets allow smaller viable reactors.
| High temperature superconductors + smaller reactors allow for a
| much simpler and smaller cooling system. Smaller reactors +
| scalable magnet design further drives down the cost. Finally,
| cost of state of art mega projects scales somewhere between 3rd
| and 4th power with the size of the device. Combining all of the
| above factors, SPARC should be here significantly sooner than
| ITER and cost a tiny fraction (I would guesstimate that fraction
| to be between 1/100 and 1/10,000).
|
| edit: typos + looked at the cost of ITER and refined my cost
| fraction guesstimate + corrected some stuff based on the reply by
| MauranKilom.
| MauranKilom wrote:
| Appreciate the rundown of why this is important!
|
| > This is because energy gain and power density scale
| exponentially with magnetic field strength but only linearly
| with reactor size
|
| Nit: It scales polynomially, not exponentially. Specifically
| (according to those formulas) energy gain scales with the cube
| of field strength and power density with the fourth power.
| Still massive scaling indeed, but exponentially would be
| something else.
|
| > as far as I remember the substrate they are using needs to be
| cooled to 60-70 degK to achieve super conductivity
|
| The video in the article shows 20 K. Could of course be that
| higher temperature is feasible and they just played it safe (or
| the video is wrong).
| TrainedMonkey wrote:
| You are right on both counts, I will update the comment. 2020
| paper referenced 7degK magnets. I am not sure where I got
| 70degK number from...
| https://www.cambridge.org/core/services/aop-cambridge-
| core/c...
| zardo wrote:
| There is a temperature dependent maximum field strength the
| material can take and keep superconducting. REBCO
| superconducts at 70k, but it can't take much current at that
| temperature.
| fabian2k wrote:
| I'm curious if they can push the magnetic field even higher in
| the near future. For smaller magnets in NMR spectrometers 20
| Tesla has been commercially available for 20 years. Of course
| this is more difficult for larger magnets.
|
| The new superconductors that allow these larger magnets are
| also very recent, not in discovery but in actual mass
| production. So they don't have as much experience with using
| these as with the classical superconductors. So I hope there is
| still quite some quick improvement there on the table.
| elihu wrote:
| I think so far the ReBCO tape is manufactured in small
| quantities by a handful of suppliers. If there were million-
| dollar orders coming in regularly, I suppose there'd be a lot
| of competition to develop the highest quality product. I
| expect it'd be like batteries; there's a lot of incremental
| improvements, and then once in awhile a major chemistry
| change. There's probably other high-temperature
| superconductors just waiting to be invented.
|
| If I remember right from one of the videos from the SPARC
| reactor folks, they were experimenting with not bothering
| with insulation between the magnet windings. The ReBCO film
| is bonded to a layer of stainless steel, and they figured the
| conductivity of the film is so much better than stainless
| steel that they wouldn't actually get much loss from current
| leaking through. That seems kind of crazy, but I guess
| there's a lot of things about superconducting materials that
| don't behave intuitively.
|
| Maybe manufacturers can make film that's bonded to a thinner
| layer of stainless steel or whatever, and thus allow for more
| windings in the same space?
| fabian2k wrote:
| I've visited a company that produces classical and high-
| temperature superconductors, though this was quite a few
| years back. I don't know the exact market size, but the MRI
| and NMR markets are probably not that small, though they
| use almost entirely classical superconductors right now.
| But they have hit the physical limits of classical
| superconductors in NMR, and the first NMRs with high-
| temperature superconductors are produced and sold now. So
| there might be some more development there even without the
| fusion angle.
|
| One purpose of the support material that isn't super-
| conducting is thermal protection. If your superconducter
| quenches, you have to dissipate the energy contained in it
| without destroying the magnet. In classical ones they use
| copper wire around them as far as I remember, and the high-
| temperature ones are a very thin film of ReBCO deposited on
| metal tape, so the actual superconductor is always a small
| part of the material.
| choeger wrote:
| ITER plans first plasma for 2025 - do you think it is a
| coincidence that SPARC is planned for 2025 as well in that
| release? I think both projects will hit delays, but ITER is
| much further in construction, so I wouldn't bet on SPARC to win
| that particular race.
|
| But they don't need to, do they? If their claim is sound, they
| could as well just optimize the magnets and wait for ITER to
| complete to offer an ITERation (pun very much intended) on the
| design. The fact that they focus on this weird race against an
| international research project makes me wonder if SPARC is
| mostly a vehicle to attract investors.
| TrainedMonkey wrote:
| I think biggest downfall of ITER is also why we must do it.
| The downfall is thus - ITER is huge and that generally
| implies lots construction delays and cost overruns. But,
| being huge also means it will be able to study sustaining
| high volume of plasma for long durations.
|
| ITERs plasma density will be comparatively low, and that is
| where SPARC with stronger magnets comes in. SPARC will
| produce data on lower volume and limited burn time, but
| significantly higher plasma density.
| jcfrei wrote:
| Lots of negative comments in this thread. I've been following CFS
| for a few years now and I honestly believe this is an historic
| event - probably the beginning of the "fusion age".
| hutzlibu wrote:
| "probably the beginning of the "fusion age"."
|
| I wouldn't call it that, even if there would be a energy gain.
|
| I call it beginning of "fusion age", when we solved fusion ad
| can build them reliable and reproducible - and if we still need
| them by that time, for main energy production.
| ncmncm wrote:
| More importantly, build and operate them for less than, say,
| 10x the best alternative.
|
| Since any fusion plant would necessarily cost more than 10x
| fission, and fission is not competitive, that is well out of
| reach.
| phendrenad2 wrote:
| What makes this such a big deal? There have been many magnet
| advances before, what makes this one different?
| ncmncm wrote:
| It is a university press release. Literally anything can be
| called a big deal.
| phscguy wrote:
| Yeah, any positive news on fusion progress and there always
| seems to be the same set of comments appear that are
| overwhelmingly critical of fusion development. Fusion is not
| well funded and imo has been let down by mismanagement of ITER,
| and despite this keeps making progress.
|
| I feel that fusion is one of humanity's best shots at actively
| reversing climate change, and it is disheartening to see such
| widespread pessimism about it. Yeah it's hard. There are huge
| hurdles in making it economicly viable, but if we can go from
| first powered flight to the moon in 70 years, and put billions
| of transistors on a chip in 50, then maybe we can get fusion
| going. It's clearly possible.
| crazygringo wrote:
| > _I feel that fusion is one of humanity 's best shots at
| actively reversing climate change_
|
| Couldn't the same thing be said about current fission
| reactors?
|
| I get that fusion doesn't have the downsides of fission...
| but I'm also worried that people will be "scared" of fusion
| in the same way they're against GMO vegetables and irradiated
| fruits, totally irrationally...
| phscguy wrote:
| Sadly no. While I think that it would work and probably be
| cheaper and easier than fusion, fission has an absolutely
| abysmal public image.
|
| People are terrified of radiation, even if the danger is
| very low. This means it becomes prohibitively difficult and
| hence expensive to build and run a fission plant because
| safety has to be prioritized so heavily. That is even if
| permission is granted to build in the first place.
|
| I think it is unlikely for irrational fear of fusion to
| become mainstream like it has with fission.
|
| Because of this I think the barriers to fusion power are at
| this point lower than the barriers to scaling up fission
| power.
| krageon wrote:
| > even if the danger is very low
|
| The day-to-day danger perhaps, but it's kind of hilarious
| in a sad way to read this right after fukushima spent god
| knows how long leaking radioactive shit into the ocean.
| phscguy wrote:
| Yeah. It's these low probability events that scare people
| away from fission. Fossil fuel pollution kills _millions_
| of people per year. Like more than 5 million. How many
| has nuclear power killed in 60 years? Probably less than
| 100,000 as a conservative estimate. Events like Chernobyl
| and Fukushima are sensational and radiation is a sexy
| topic. People dieing of lung cancer from air carcinogens
| produced by coal burning is not.
| nickik wrote:
| Fusion also produces radiation. So not sure why changing
| one word to the other should magically change public
| opinion.
|
| We can just rename fission to #goodenergy or something,
| that would be cheaper then developing fusion.
|
| People don't even know that nuclear reactors use fission,
| so the idea that this would change anything is crazy.
| People opposed will call fusion reactors 'nuclear' just
| like they do fission.
| zaarn wrote:
| Fusion Radiation is only immediate, ie, only in the area
| where the reactor is. And it can be contained with
| comparatively little effort, even put to use to breed
| Tritium for more Fusion fuel.
|
| If a Fusion reactor blows up, the radiation risk is
| basically 0, aside from the lack of potential melt downs.
| phscguy wrote:
| The amount of long lived radioactive material produced by
| fusion reactors is many orders of magnitude less than
| fission. Iirc it's about the same amount of the
| radioactivity released as burning coal in a coal plant of
| the same power output.
| lambdatronics wrote:
| Yeah, I don't have much hope that the general public will
| understand the nuances here, especially if the greenies
| decide to mount a PR campaign against it. OTOH, we can
| call it "fusion" instead of "nuclear fusion" and that
| will undoubtedly help. (lol)
|
| Fusion does indeed come with radiological hazards: a fire
| could release radioactive gas and dust. If designed
| right, the worst-case scenario would still be way less
| severe than for a fission plant -- and the worst-case
| scenario is really what stokes all the popular fears
| about 'nuclear'. OTOH, tritium leakage could mean that
| routine emissions are larger.
| redis_mlc wrote:
| > they're against GMO vegetables and irradiated fruits,
| totally irrationally...
|
| COVID-19 is GMO ... are you in favor of pandemics?
| ncmncm wrote:
| There is no need worry about that. Extreme high cost will
| suffice. It could never come within 10x fission cost. You
| might notice people are not breaking down doors to build
| fission plants.
| UnFleshedOne wrote:
| There is a species of environmentalism that would consider
| successful fusion or similar high tech mega scale energy
| source actually detrimental because you can't build one in
| your hippy community using old tractor parts and alternative
| ways of knowing.
|
| Environmentally clean energy source is not enough, it needs
| to be ideologically pure as well.
| pfdietz wrote:
| This is projection. The irrationality is thinking that
| fusion is something desirable. I suspect this follows from
| exposure to fusion reactors as a trope in SF stories. From
| a hard nosed engineering point of view fusion is just
| terrible.
| phscguy wrote:
| I can understand that from an enginneering perspective
| ITER is terrible, but fusion in general?
|
| There are all sorts of approaches to fusion, and things
| such as type 2 superconductors were undiscovered 30 ago
| and uneconomic/unpractical 10 years ago. Timing control
| systems for magnetised target fusion were impossible but
| now are doable. Our understanding of plasma has been
| advancing a lot, simulations are good now, we can control
| plasmas much better. Chirped pulsed laser amplification
| is a thing now and really good at making high amplitude
| pulsed lasers for inertial approaches...
|
| I could go on and on. This isn't the 90s anymore, and our
| technology is still rapidly advancing. What happens if we
| find more efficient/cheap/high power density
| thermocouples, or find a direct energy electrostatic
| power capture method?
|
| Fusion's economic realities today may be overcome soon,
| we really do not know what we can do in even 20 years
| from now. The fundamental truth is that there is vast
| amounts of energy available in hydrogen, and all it takes
| is 100MK to ignite it.
| pfdietz wrote:
| DT fusion looks bad even if you totally ignore anything
| related to plasma physics or magnetic fields. Simply
| handling the heat flow and neutrons from the reactor
| looks to make the reactor too big to compete, compared to
| fission reactors.
|
| And then you have the problem of having to stick
| sophisticated stuff in the hot zone where hands-on
| maintenance is impossible (compared to a fission reactor,
| where just the fuel and relatively simple hardware is in
| that zone.)
| gfodor wrote:
| Fusion doesn't have the stigma of fission, or a lot of
| the risks, and so if we can get to a point where we are
| actually building new fusion reactors, we should assume
| the technology will improve rapidly.
| pfdietz wrote:
| It's a common error to think that fission power plants
| aren't being built because of "stigma". The actual
| problem is failed economics. Fusion promises to be even
| more expensive, for the reasons I explained.
|
| It's not clear why one should expect fusion to have good
| experience effects. Fission didn't, and the non-nuclear
| parts of fusion power plants will be mature technologies.
| gfodor wrote:
| Your argument is that the stigma of nuclear meltdowns
| hasn't impeded the deployment of nuclear energy?
| pfdietz wrote:
| If reactors were ten times safer but no cheaper, they
| still wouldn't be being built.
|
| If reactors were ten times cheaper but no safer, we'd be
| building them like hotcakes.
| nickik wrote:
| While this is true, its a fact that the regulatory and
| governmental outlook on fission has prevented these
| changes from happening.
|
| The western world has made development of new fission
| plants practically impossible. Requiring 100s of millions
| in development before you might get a hint if the
| government would actually allow you to build a plant.
|
| Thankfully this has finally started to change. Mostly in
| Canada and that's where we will likely see next
| generation fission first.
| pfdietz wrote:
| Regulation is the scapegoat for nuclear's failure, but
| it's equally the case that regulation is vital to nuclear
| (and to nuclear getting liability caps.) If the risk of
| nuclear were not socialized no one would build it (or
| insure it).
|
| What has also prevented changes from happening is that
| nuclear scales down poorly, so the cost of iterating
| designs is so large. Making a new kind of PV cell or
| module, or wind turbine, is comparatively much cheaper,
| because these are individually much smaller and cheaper.
| The replicated nature of these sources is an advantage in
| so many ways.
| lwouis wrote:
| I think Japan disabling their fission plants after
| Fukushima, and Germany following that path are clear
| manifestation of the opposite: that people fear nuclear
| and democratic governments act on this fear, against
| development of the technology.
| sprafa wrote:
| Please tell me how it's terrible, Mr Hard Nosed Engineer
| ?
| pfdietz wrote:
| Low power density (at least an order of magnitude worse
| than fission), high complexity, need to maintain large
| complex objects for which hands-on maintenance is
| impossible and for which there are many parts for which
| no redundancy is possible. Fusion reactors are the
| opposite of "Keep It Simple, Stupid".
|
| The engineering undesirability of DT fusion has been
| known for decades. All the recent excitement doesn't
| address any of the known showstoppers.
| sprafa wrote:
| You sound like someone Id love to see proven wrong.
| mcswell wrote:
| Like Mr Fusion? runs on beer, from what I've seen.
| john_yaya wrote:
| The magnets are a problem to solve, but not the biggest problem
| by far. Solve for neutron embrittlement of the reactor parts, and
| then you'll start to have some credibility.
| lambdatronics wrote:
| Fusion scientist here (no connection with MIT/CFS). This is in
| fact a very big deal. One of the chief complaints about fusion
| energy is the low power density (for ITER-like tokamak <<1MW/m^3,
| vs ~ 100MW/m^3 for a LWR fission core). The low power density is
| the primary reason that ITER is as large (and hence expensive) as
| it is.
|
| Fusion power density scales like B^4. So if CFS can get 2x the
| magnetic field, then they can make the plasma volume 16x smaller,
| which might equate to big savings in cost and construction time.
| (It doesn't make sense to go much smaller than their ARC reactor
| design though -- the plasma already takes up only a fraction of
| the volume of the core at that scale, so compressing the plasma
| further doesn't improve the power density. If you can increase
| the field even more, which REBCO seems to allow, then you would
| rather just pack more power into a device about the size of ARC.
| So don't expect to put one of these on your DeLorean.)
|
| There are definitely other challenges/limitations. For one, this
| approach increases the heat flux that the inner wall of the
| reactor will have to survive. The localized heat flux of the
| exhaust stream is expected to rival the heat flux of re-entry
| from orbit (20 MW/m^2) and could be as high as the power flux
| from the surface of the sun (~60MW/m^2). 20MW/m^2 is on the hairy
| edge of what's possible with today's technology, and that's
| without all the complications of neutron damage, plasma
| bombardment, etc. The current thinking is to spike the outer
| layer of the plasma with neon or nitrogen, to radiate most of the
| power as photons, but there are limitations & risks to that idea
| as well. Commonwealth's plan for SPARC (last I heard) was to
| oscillate the exhaust stream back & forth across the absorber
| plate to reduce the average heat flux.
|
| The nuclear engineering side of fusion has been underfunded for a
| long time, so there's much that needs to be done on that front,
| in terms of demonstrating that the breeding of tritium from
| lithium can be done efficiently & without too much losses. Also,
| we should be developing better structural materials that can
| withstand neutron damage & not become (as) radioactive.
|
| It's still very much an open question as to whether fusion could
| be made economical, even though it seems like it should be
| technically possible.
| nielsbot wrote:
| Update: They have a press release on their website
| https://cfs.energy/news-and-media/cfs-commercial-fusion-powe...
|
| In case others are wondering, looks like this is for SPARC.
|
| FTA: This "MIT-CFS collaboration...on track to build the world's
| first fusion device that can create and confine a plasma that
| produces more energy than it consumes. That demonstration device,
| called SPARC, is targeted for completion in 2025."
|
| CFS: https://cfs.energy/technology
|
| (edit: clarification)
| oseityphelysiol wrote:
| Question from a layman: how will the energy from a fusion reactor
| be extracted and converted into electrical energy? As far as I
| understand, the plasma inside a tokamak is isolated from the
| surroundings by the use of very powerful magnets. I assume in a
| reactor that is supposed to generate electricity there would be
| some interface between the plasma and some kind of heat exchanger
| that would generate steam and turn gas turbines?
| jokteur wrote:
| Neutrons that escape the tokamak arrive in a lithium mantle
| around the reactor, which produces helium and some heat. The
| heat is extracted from the lithium mantle, and then you have a
| conventional gas turbine.
|
| This is what I remember from memory, I would need to fact check
| that.
| tsimionescu wrote:
| Yup, plain old heating water to make steam to turn a turbine.
| noobermin wrote:
| University press releases need not be peer reviewed so they can
| get close to saying things that would offend other scientists and
| get away with it. The key phrase in "the most powerful magnetic
| field of its kind ever created on Earth" is "of its kind."
| Creating a many telsa magnetic field has been done in other
| experiments like with lasers[0], only they are physically smaller
| in size and last for nanoseconds, it's just of this size,
| stability and with the high temperature superconductors that
| makes it special. If the claim is just the magnitude of the field
| they've already been beat.
|
| [0] https://www.nature.com/articles/s41467-017-02641-7
|
| Just as a note, the max B field here is 600T
| zardo wrote:
| I think "it's kind" refers specifically to a magnet for plasma
| containment. As this doesn't set the record for a REBCO magnet.
|
| https://nationalmaglab.org/news-events/news/lbc-project-worl...
| shmageggy wrote:
| These university press releases are always very positively
| framed. This one makes the new magnet seem incredibly promising
| and fusion seem like almost an inevitability now, but decades of
| failure have us conditioned for skepticism. What's the catch this
| time?
| anonuser123456 wrote:
| > What's the catch this time?
|
| This is D-T fusion. Which means you have to have T. Which
| currently comes from fission reactor and has a half life of 15
| years.
|
| So the plan is to use a molten salt blanket with Be to breed T.
| But Be isn't scalable for consumption, so maybe lead
| eventually. That's probably do-able, it just slows down the
| rate new reactors can come online since Pb is not as good a
| neutron multiplier.
|
| Once they breed extra T, they have to capture and refine it.
| Hydrogen is very corrosive and hard to work with... and T is
| radioactive hydrogen. Again, probably doable. But guess what?
| Refining spent nuclear waste in fission reactors is also do-
| able. It's also super expensive.
|
| And they still need a containment vessel that will withstand
| the wear and tear from sitting next to a mini hydrogen bomb all
| day.
|
| These challenges are likely all surmountable. But are they
| surmountable AND cheaper than existing nuclear or other energy
| sources? Meh?
| worldvoyageur wrote:
| Tritium is a natural byproduct of CANDU fusion reactors, of
| which there are some 25 or so in operation globally, mostly
| in Canada. CANDUs use heavy water as a neutron moderator (D20
| instead of H2O), making T2O a natural byproduct.
|
| Though most of the reactors do not harvest the tritium, a
| small number do.
|
| CANDU operators have long been ready to make the capital
| investments in tritium harvesting, once demand materializes.
| ITER has long been seen as a potential major source of
| tritium demand.
| anonuser123456 wrote:
| I think the SPARC guys are going to eat all the CANDU
| tritium before ITER ever gets a chance light up.
|
| If we have to scale up fission reactors to produce enough
| tritium to scale fusion reactors, then don't need the
| fusion reactors.
| codesnik wrote:
| (you probably meant to write "CANDU fission reactors")
| snek_case wrote:
| I'm wondering, fusion reactors themselves produce neutron
| radiation as a byproduct. Once you have a fusion reactor
| running, could you use the fusion reactor itself to breed
| tritium?
|
| Also thinking, we target deuterium + tritium fusion because
| it's the least energy intensive. However, once we have
| working proof of concept reactors, could we just make them
| slightly bigger and fuse more abundant molecules/isotopes
| instead?
| carbonguy wrote:
| > Once you have a fusion reactor running, could you use
| the fusion reactor itself to breed tritium?
|
| I'll have to find the citation, but IIRC the answer is
| "theoretically, yes" - the concept is that molten lithium
| could be used in a tokamak to absorb neutrons and produce
| tritium at the same time.
|
| EDIT: Here are two citations I was able to find quickly -
| it looks like one of the ITER experiments will be to
| validate the concept [1] and that this could also be the
| way that heat is removed from the reactor. [2]
|
| [1] iter.org/mach/TritiumBreeding
|
| [2] https://www.euro-fusion.org/faq/top-twenty-faq/what-
| is-a-lit...
| anonuser123456 wrote:
| While not listed in the article, this is the design goal
| of the SPARC reactor.
|
| Their plan is to use FLiBe (Google it) blanket to breed
| tritium. The Be acts as a neutron multiplier.
|
| As for non D-T fusion, the next best candidate is D-He3.
| Unfortunately, the only large scale source of He3 is on
| the surface of the moon and it would have to be mined, on
| the moon, and sent back to Earth.
| dmix wrote:
| A study on feasibility of lunar He3 mining https://ui.ads
| abs.harvard.edu/abs/2014cosp...40E1515K/abstra...
|
| Not as bad as I expected but not yet feasible economic
| wise. Assuming the fusion part exists.
| mcswell wrote:
| "Hydrogen is very corrosive and hard to work with" Corrosive
| compared to what? You can put it in a rubber balloon and hand
| it to a kid.
|
| "T is radioactive hydrogen": True, it emits low energy beta
| radiation, which is an electron, and is stopped by a sheet of
| paper. I used to have a wrist watch with a tritium dial; I
| haven't died of cancer yet.
| snek_case wrote:
| Corrosive is the wrong word, but hydrogen is such a small
| molecule, it can leak through metals and weaken them, as I
| understand it. It's hard to contain.
|
| https://www.imetllc.com/hydrogen-embrittlement-steel/
| GordonS wrote:
| > Corrosive compared to what? You can put it in a rubber
| balloon and hand it to a kid.
|
| I've never heard of hydrogen-filled balloons (at least not
| the kind of balloon you can hand to a kid) - we're you
| thinking of helium?
| bjowen wrote:
| It's a high-school level laboratory experiment. Nobody's
| handing them out at birthday parties[0], but mostly
| because hydrogen likes to go bang loudly, not because
| it's corrosive or toxic or anything.
|
| [0] unless Mark Rober is involved in some way.
| OJFord wrote:
| > This is D-T fusion. Which means you have to have T.
|
| For the other uninitiated, (or far enough out of secondary
| school and didn't take it further!) this seems to refer to
| Deuterium-Tritium fusion, D & T being the isotopes of
| hydrogen with an atomic mass of 2 (1 neutron, 'heavy' but
| stable) and 3 (2 neutrons, radioactive) respectively.
| rnhmjoj wrote:
| > But are they surmountable AND cheaper than existing nuclear
| or other energy sources?
|
| DT fusion solves the two biggest arguments that are always
| raised by nuclear energy opponents: storage of nuclear waste
| (it doesn't produce high-level waste) and safety (it's not
| perfect but it can't explode). I wouldn't call it a "meh",
| even if it comes off as much more expensive than fission.
| mordymoop wrote:
| I had heard that one of the major drawbacks of tokamaks was
| the incredible temperatures lead to situations where the
| smallest mechanical failure will lead to an explosion of
| hot, radioactive gas. Is that not the case?
| ncmncm wrote:
| That would be the least of its problems.
|
| Costing hundreds or thousands of times as much as solar +
| storage is a more serious problem. Since it won't be
| built, that is a theoretical problem. But the project can
| absorb an unlimited amount of money first.
| pas wrote:
| The whole amount of gas in the chamber is just a few
| grams.
|
| Tritium is not pleasant though, but veeeeeeeeery far from
| anything that could do real harm:
| https://en.wikipedia.org/wiki/Tritium#Health_risks (you'd
| need to leak a lot of it continuously)
| rnhmjoj wrote:
| Temperature is not a very good quantity to gain intuition
| about plasmas (or heat transfer in general): the
| temperature of the electrons in a incandescent light bulb
| is around 10000 K, which seems very hot, but since their
| density is much lower than the air density, the powers
| involved are quite small and a light bulb is pretty safe
| to touch.
|
| In the same way, a fusion plasma doesn't hold that much
| energy because of the extremely low density (4x10^-6 that
| of air). An explosion (a runaway/chain reaction) is also
| not possible: the reactor must continuously supplied with
| fuel or the fusion reactions will stop in a matter of
| seconds.
|
| There are situations which could result in significant
| damage to the reactor components, but still not a public
| safety concern. Distruptions are events in which the
| plasma confinement is lost and a large amount of heat is
| released that could damage all components that face the
| plasma, but reactors are designed to withstand this.
|
| Another drawback, if you like, are runaway electrons,
| which are populations of relativistic particles that
| become unbound and penetrare the vacuum vessel for
| several mm. Again, this is not a particular issue from a
| safety point of view, but they can do a lot of damage: if
| they hit a magnetic coil and cause a loss of the
| superconductivity state, the coil can heat very rapidily
| (due to the huge current that goes through it) and
| potentially melt. Replacing such a coil could cost years
| of maintenance, for this reason reactors are build with
| many fallback systems.
| lambdatronics wrote:
| Yeah, but nuclear energy opponents aren't the reason
| fission isn't getting built -- it's primarily about the
| cost.
| danans wrote:
| > I wouldn't call it a "meh", even if it comes off as much
| more expensive than fission.
|
| It's not competing with fission, though. It's competing
| with renewables + storage + load shifting + efficiency.
| Compared to those, it might indeed be "meh".
| jonnycomputer wrote:
| I am generally in support of solar and wind. But then,
| people underestimate the environmental destruction those
| can entail, depending on the site. Yesterday, I saw a
| hillside in a very rural part of Appalachia covered in
| solar panels. Nothing grew on the hill. Because, you
| know, plants would cover up the panels in no-time, so you
| have to vigorously keep all of it in check, with
| herbicides. Aside from the loss of potential carbon
| storage from allowing trees to grow on the hillside,
| which very well might offset any carbon-related gains
| from using solar, it's just bad for the ecology (which is
| exceedingly rich in the vicinity). Any farm typical for
| the area would be multiples of times better.
|
| This is not intended as a rant against solar (again, I'm
| an enthusiastic supporter), but I'd guess a landscape of
| fusion generators would take fewer square meters of land
| than the equivalent using solar. And that is nothing to
| scoff at.
| danans wrote:
| > Aside from the loss of potential carbon storage from
| allowing trees to grow on the hillside, which very well
| might offset any carbon-related gains from using solar,
|
| It is incredibly unlikely to offset the carbon related
| gains of solar, because the carbon sequestration
| efficiency of plants and trees is very low to begin with,
| far lower than solar's capacity to displace carbon
| emitted from coal when area is held constant.
|
| Sure, it's better to put the solar where there is no
| existing tree cover, but it seems like most of Appalachia
| is covered in trees.
| rnhmjoj wrote:
| Agreed, but grid and storage technology that will
| completely solve the renewable intermittence is probably
| as far in the future as commercial fusion reactors.
| ncmncm wrote:
| The only open question about large-scale energy storage
| is which of many viable alternatives will turn out
| cheapest, and when their price will bottom out. Battery
| storage that starts at 1/3 of lithium cost, before price
| begins to fall, is coming to market.
|
| Until prices do start to bottom out, investment in
| storage is wasteful, so dollars go to generating capacity
| of known utility.
|
| Each square meter of panel that goes online delays
| climate disaster by a precisely understood amount. Each
| panel made can go into service almost instantly. No
| matter how big the project, it can start delivering power
| anytime. There is no smallest-useful facility, right down
| to the residential rooftop.
|
| Every dollar diverted to Tokamak instead brings climate
| disaster nearer.
| [deleted]
| pfdietz wrote:
| This is a gross mischaracterization of the situation.
| There are a wide variety of energy storage schemes that
| promise to make renewables + storage cheaper than
| fission, which in turn is likely to be much cheaper than
| fusion. Simply dumping excess renewable power into a
| resistively heated thermal mass and using that to drive a
| power plant is likely to be cheaper than fusion.
| UnFleshedOne wrote:
| In the grid this would take role of coal or gas plants
| for base load, no?
| danans wrote:
| Storage at sufficient scale would supply some of what we
| refer to as baseload today, much as hydro provides
| baseload power in many places today.
| r00fus wrote:
| For terrestrial operations, sure. But we need to either
| overcome shielding hurdles with fission or have
| relatively portable fusion if we're really going to
| explore our solar system or the stars.
|
| Renewables are key to having a sustainable energy
| economy. Fusion power is what will let us do the drastic
| things to recover from climate disaster that is already
| here.
| nickik wrote:
| Very questionable if a fusion reactor is safer then a
| common molten salt fission reactor. I would argue that is
| far less likely to 'explode'.
|
| And you can burn up the waste majority of that waste, the
| leftover waste after that would not really a huge issue.
|
| Both of these are far more political problems then actual
| real problems a society based on modern fission would have.
| Symmetry wrote:
| The problem with fission reactors in general is that
| after you stop the chain reaction you've still got a
| tenth or so of the power output you had when it was on
| from decay heat for a while and you need a reliable way
| to get rid of that heat even in the event of a disaster.
| With fusion the nice thing is that the new heat stops
| appearing as soon as the reaction stops.
| speed_spread wrote:
| It sounds like the T production chain might itself be quite
| messy. Molten isotopes salt and lead? How much of that
| stuff would you need? What do you do with when it goes bad?
| It may not go boom Chernobyl-style, but it's still far from
| the birds-in-the-sky deuterium-from-the-sea fusion dream.
| scythe wrote:
| The bad zone of radioactive byproducts is the half life
| between 10 and 1000000 years. Shorter and you can wait it
| out. Longer and the activity is low enough to ignore when
| it's spread out. When designing a fusion reactor, you can
| usually choose components that won't generate these
| undesirable nuclides. But in fission, many products are
| generated, so persistent contamination is practically
| impossible to avoid.
| rnhmjoj wrote:
| > It sounds like the T production chain might itself be
| quite messy.
|
| It is: it's definitely the biggest challenge after plasma
| confinement.
|
| > Molten isotopes salt and lead?
|
| There are two main blanket technology in development:
| ceramic and liquid breeders. They're called breeders but
| are very different from the kind of breeders you have in
| a fission reactor. Both are based on converting lithium
| to tritium by capturing fusion neutrons, but in one case
| the lithium is in the form of solid pebbles, while in the
| other, in a molten mixture of lithium-lead (there are no
| salts AFAIK).
|
| To produce more tritium than you start with you also need
| a neutron multiplier: beryllium in ceramic breeders and
| lead in liquid breeders. The problem is beryllium is rare
| (and also toxic): a 500MW reactor needs ~200 kg/year,
| which is not a lot, but there's very very little
| beryllium on earth. If you factor in the initial reactor
| inventory (170 t/reactor) it turns out ubiquitous fusion
| energy it's not sustainable if we choose beryllium. If
| you go with lithium-lead you need more material: 3 t/year
| (but remember lead is a lot heavier and more common too).
| If you plan to cover the world energy base load with
| fusion, you would need a lot of lead (~10% world annual
| production) but it's doable.
|
| For me, the biggest problem right now is lithium: DT
| fusion needs lots of pure 6Li, which is extracted by
| enriching even more natural lithium. If we're not careful
| enough with recycling it from old batteries, we are
| likely to exhaust the world resources in a few decades.
|
| > What do you do with when it goes bad? It may not go
| boom Chernobyl-style, but it's still far from the birds-
| in-the-sky deuterium-from-the-sea fusion dream.
|
| The worst case scenario is still the loss of coolant
| accident (LoCA). The blanket is exposed to a ~2MW/m2 heat
| load from the plasma (in addition to all kind of
| radiation), so failing to cool adequately a module means
| it will very rapidly turns into a (radioactive) molten
| mess that's not easy to handle. Yeah, it's bad but not
| nearly as bad as the same accident in a fission reactor.
| ncmncm wrote:
| Destroying your $300B power station is entirely bad
| enough.
|
| If we are lucky enough, none will be built.
| baybal2 wrote:
| > storage of nuclear waste (it doesn't produce high-level
| waste)
|
| It does. You cannnot fuse just D+T, other trace gasses, and
| lighter isotopes will be present as well.
| rnhmjoj wrote:
| No, it doesn't in any significant quantity [1]. Besides,
| there are practically no high Z elements in a fusion
| plasma. That's because they emit bremsstrahlung radiation
| (power grows like Z2) and rapidly cool off the plasma. If
| the reaction is to be self-sustained, the plasma charge
| averaged over the density (Zeff) must be kept as close as
| possible to 1. Considering that there's only a few grams
| of material in a full reactor, there are virtually no
| heavy elements.
|
| The radiative losses do exist, but are caused by detached
| atoms from the plasma facing components. Everything close
| to the plasma is made of light elements and specifically
| chosen to not produce dangerous radioisotopes when
| neutron activated: no high-level waste materials, meaning
| the half-life is lower that 10 years and they can be
| recycled in around 100 years.
|
| [1]: http://www.iter.org/faq#Can_you_declare_fusion_is_re
| ally_saf...
| [deleted]
| stormbrew wrote:
| I'm not sure it's possible for "lay people" (of which I am one)
| to recognize the difference between a very slow success and
| "decades of failure".
|
| Very little is invested into fusion power as a project,
| overall. So advancements seem to come when outside influences
| cause breakthroughs.
|
| I wonder how different the world would have been if it had for
| whatever reason been easier to produce fusion power than a
| fusion bomb. Military investment into the bomb would have
| probably pushed things forward a lot quicker. As is, the US
| military built thermonuclear bombs _very_ quickly and then the
| appetite for advancement just dried up.
| fshbbdssbbgdd wrote:
| You could say that military investment into fusion and
| fission bombs was groundwork for everything done since. On
| the other hand, the fact that nuclear power started with
| bombs probably contributed to it falling out of favor and
| being regulated to irrelevance (even though hydrocarbons have
| been responsible for a lot more deaths and environmental
| damage).
| phkahler wrote:
| >> What's the catch this time?
|
| There are a bunch of issues still to be resolved. Higher magnet
| strength is/was just one of many.
| ncmncm wrote:
| That the most expensive parts of the plant would be quickly
| destroyed by neutron irradiation is another.
|
| That it would cost overwhelmingly more than solar+storage is
| what will ultimately kill it. Someday. Many more $B will be
| spent first.
| azalemeth wrote:
| Agreed. Whilst it may well be the largest, highest-field "only"
| high Tc superconductor design in the world, it's definitely not
| the highest-field high Tc superconducting magnet -- I believe
| that honour belongs to another bit of MIT with a 1.3 GHz NMR
| machine [1] (but I do remember something about Bruker
| collaborating with the US's National Magnet Lab and building a
| 30T machine -- I can't easily find a link).
|
| I really wish that press release would put the link to the
| paper at the top -- I found it very hard to work out what was
| actually new!
|
| [1] https://ieeexplore.ieee.org/document/6926794
| maccam94 wrote:
| The magnet with the strongest magnetic field isn't
| necessarily the best engineering solution for a fusion
| reactor. In particular, these magnets need to be cooled
| (plumbing can be bulky and coolant can be difficult to work
| with) and allow for easy servicing of the reactor components
| (particularly the vacuum vessel which will need replacing
| every ~10 years due to neutron embrittlement). This magnet
| design is noteworthy because of several factors: high-
| temperature superconductivity means they're cheaper and
| easier to cool, the high field strength allows for a smaller
| scale reactor, and the physical construction of the magnets
| makes them cheap to build and allows for easy disassembly
| during maintenance periods.
| baking wrote:
| That paper refers to a different magnet. The press release
| refers to milestone that was achieved a few days ago and has
| not yet been published. Their goal announced three years ago
| was to build the magnet and demo it this Summer. Let's just
| say they squeaked in under the wire since traditionally
| Summer ends in the US on the first Monday of September.
| (Unless you want to go with the equinox.)
| bb88 wrote:
| This was a 32T field created, not sure if it's the same, but
| similar.
|
| https://english.cas.cn/newsroom/research_news/tech/201912/t2.
| ..
|
| Googling "30T magnetic field" shows some papers that have
| apparently "pulsed" 30T.
| apendleton wrote:
| I think the framing of what's happened so far as "failure" is
| probably the main thing responsible for this perception. It's
| true that progress has been slower than many had hoped and the
| most optimistic had projected, but "failure" sort suggests that
| the things the research community have been trying haven't
| represented meaningful progress towards the goal of power
| production, which isn't the case.
|
| Q (the ratio of energy out to energy in) has improved by about
| four orders of magnitude since controlled fusion was first
| achieved, and it's been a slow, at least reasonably steady
| march since the middle of the 20th century to achieve that
| progress. The current record-holding Q for magnetic confinement
| is around 0.67, so we need well under one more order of
| magnitude to get to the point of "theoretical break-even" (Q>1)
| -- we're most of the way there. A plant just barely better than
| break-even probably wouldn't be commercially viable, though,
| and while estimates vary, that point is probably somewhere in
| the 10-30 range, so we have maybe another order of magnitude to
| go after break-even. I don't think there's anything to suggest
| that after decades of progress we'll suddenly stop being able
| to make more.
|
| It's true that things have slowed down somewhat in the last
| 10-15 years, but most of the blame there goes to the need, in
| order to continue moving forward, to build bigger and bigger
| reactors, and the need to divert resources to that goal (mostly
| ITER). To the extent that promises of going faster have turned
| out to be hot air, it seems like they've mostly been in the
| form of novel approaches that do fusion in some fundamental new
| way that avoids the need to build an ITER-like thing. These
| approaches seem to often involve lots of unknowns, and end up
| getting bogged down in practical issues once they're actually
| tried (surprise plasma instabilities and so on).
|
| Recent advances in materials science (mostly REBCO magnets) and
| computing, though, offer a path to progress on the regular,
| bog-standard flavor of magnetic confinement fusion (tokamaks)
| on a smaller scale -- that's what this is. The nice thing about
| that is that the plasma physics here are very well understood,
| and have been heavily researched using conventional/not-super-
| conducting magnets that won't ever achieve break-even, but
| create identical plasma conditions inside the reactor (MIT
| Alcator C-Mod is effectively the conventional-magnet
| predecessor to this project). Up until now, the only real
| question was whether or not they could build strong-enough
| REBCO magnets, and now they have, so this is all good news and
| reason for optimism.
|
| Of course, commercial viability is a whole other question
| involving lots of questions besides physics. But the physics
| here seem to not be in serious doubt, unlike some of the
| proposals from other startups that are more exotic.
| zardo wrote:
| Would stellarators see the same benefits as tokomaks from
| higher field strength magnets?
| apendleton wrote:
| Potentially yes, though stellarator research in general
| seems to be somewhat less mature than tokamak research.
| There's an outfit called Type One Energy, though, that
| looks to me like they're essentially CFS but for
| stellarators (i.e., take established stellarator designs
| but do them with HTS magnets):
| https://www.typeoneenergy.com/ . Their academic heritage
| seems to come out of the University of Wisconsin instead of
| MIT.
| eigenhombre wrote:
| > Recent advances in materials science (mostly REBCO magnets)
| and computing, though, offer a path to progress ...
|
| What sort of computing advances? Modeling? Real time
| controls? I'm guessing modeling, but would like to know more
| details.
| pjmanroe wrote:
| I just read an article about this tonight on Sciencex.com I
| believe. It was impressive.
| pjmanroe wrote:
| I just read an article about this tonight on Sciencex.com I
| believe it was. It was impressive. It reached 20 teslas in their
| test.
| pjmanroe wrote:
| I just read this article tonight on Sciencex.com or .org. It was
| quite impressive. They reached 20 teslas in their test.
| [deleted]
| ghego1 wrote:
| From a economical/political point of view I find very interesting
| and promising that CFS is participated, amongst others, by one of
| the largest oil company in the world (ENI), which signal a real
| effort to move away, or at least strongly differentiate, from
| fossil fuels.
| xqcgrek2 wrote:
| Ah, a university press release.
|
| Nah.
| sdeyerle wrote:
| In the original proposal for the ARC reactor, they were proposing
| making the magnet separable so the top and bottom of the reactor
| could be separated and the vacuum vessel removed. (See pg. 5 of
| https://library.psfc.mit.edu/catalog/reports/2010/15ja/15ja0...)
|
| It doesn't look like they are targeting that here. Does anyone
| know if that is ARC (not SPARC) specific, or if that has been
| abandoned?
| nielsbot wrote:
| The article says this is from an "MIT-CFS collaboration" which
| is "on track to build the world's first fusion device that can
| create and confine a plasma that produces more energy than it
| consumes. That demonstration device, called SPARC, is targeted
| for completion in 2025."
|
| So, sounds like it's for SPARC.
| sdeyerle wrote:
| Yeah, they are definitely building SPARC. I had just been
| under the impression they were trying to do the separable
| magnets in SPARC, and was curious if I misunderstood their
| plan or if their plan had changed.
| nielsbot wrote:
| Yeah--I misread your question. :)
| [deleted]
| ncmncm wrote:
| Since there is no actual use planned for any power released in
| this gadget, no maintenance will be performed. When they finish
| playing, they scrap it, pocket the money, and go their separate
| ways.
|
| No commercial reactor will ever be built, so this is just for
| showing off.
|
| The only real good to come from these efforts is employment of
| plasma fluid physicists. I just hope non-military work can be
| found for them when this stuff fizzles. Solar Physics is
| fascinating and important, but has limited budget.
| elihu wrote:
| I think that's ARC-specific. SPARC is a prototyping platform,
| they aren't designing it for long term use or to be
| refurbished.
| baking wrote:
| The demountable magnets for ARC are so the blanket and vacuum
| vessel can be swapped out as a whole unit for replacement
| during maintenance. SPARC has no blanket and will only be used
| for some thousands of ten second shots or the equivalent of a
| week or two of continuous operation. The magnets being
| unshielded will probably fail before the vacuum vessel does.
|
| CFS will be building a lot more magnets, not only for SPARC but
| for other customers, physics experiments and medical equipment,
| so I expect they will be working on many additional features
| including demountable joints for ARC.
|
| One of the early tests they did of the VIPER cable at the
| SULTAN test facility in Switzerland involved a joint formed by
| clamping the ends of two cables to a copper bar. It does show
| that resistive joints are possible with HTS cables, unlike LTS
| cables, but the actual configuration of a joint for a large
| magnet is obviously a different matter. Luckily they will have
| a few years to work on it.
| JDDunn9 wrote:
| Even if we can get fusion to work, it will never be economical.
| Just because the fuel (water) is free, that doesn't make the
| energy free. The fuel rods for fission power plants are already a
| rounding error in the cost of energy. It's the capital costs that
| dominate the equation, and fusion plants will be at least as
| expensive as fission, which is more expensive per KWh than solar.
|
| https://thebulletin.org/2017/04/fusion-reactors-not-what-the...
| gfodor wrote:
| You're citing an article from 2017 talking about a reactor
| design from 1988 in response to an article about novel fusion
| technology from 2021.
| loufe wrote:
| I agree that the sourcing does seem off in JDDunn9's post but
| your comment doesn't invite further discussion much.
| pjmanroe wrote:
| I read an article about this tonight on ScienceX.com or .org. It
| was quite impressive. They reached 20 teslas in their test.
| Mizza wrote:
| Are there other cool things we can do with this magnet tech?
|
| For instance, can I build a railgun to shoot things into orbit?
| dfdz wrote:
| The thumbnail of the youtube video made me laugh
|
| Smaller. Smarter. Sooner. 2018
|
| Currently 2021 where is my fusion energy? But this time must be
| different, after this advance we are only a few years away from
| fusion energy?
| baking wrote:
| The company was founded in 2018. At the time they promised to
| demo this magnet during the Summer of 2021. What is the issue?
|
| The goal is to get fusion power om the grid in the 2030's and
| scale up in the 2040's. Stop moving the goalposts.
| bwestergard wrote:
| They seem to have made two claims. First, that they have a
| qualitatively different design that requires a significantly
| stronger magnetic field. Second, that they could build a magnet
| that produces such a field.
|
| They are now claiming to have done the latter. Are you
| skeptical of the new design? Or do you think it does not
| represent as significant a departure from earlier designs as
| they claim?
| ChrisMarshallNY wrote:
| The running joke has always been that "Fusion is 20 years
| away," and has been, for the last 50 years.
|
| I really want this to work. I am a bit concerned, with how "the
| old guard" will react, once we have successful, productive,
| fusion.
|
| I foresee an astroturf NIMBY campaign against construction of
| fusion plants.
| phicoh wrote:
| At the moment it is very far for clear that fusion will be
| cost effective. The article says this about the fuel of
| fusion: "The fuel used to create fusion energy comes from
| water, and "the Earth is full of water -- it's a nearly
| unlimited resource. [...]"
|
| They forgot to say that it is not the H2O that comes out of
| your tap. The earth is especially not full of tritium.
| apendleton wrote:
| The plan is for them to breed their own tritium, though, so
| the consumables coming in the front door would just be
| deuterium and lithium, both of which (while less common
| than tap water) are not rare.
| eropple wrote:
| My understanding (and I am a layman) is that lithium
| isn't _that_ accessibly common on Earth, and that we 're
| doing a bang-up job of using as much of it as we can get
| our hands on already. Are there practical methods of
| extracting less accessible lithium that don't themselves
| have nasty side effects?
| apendleton wrote:
| Yeah, there have been rumblings about recovering it from
| seawater: https://electrek.co/2021/06/04/scientists-have-
| cost-effectiv...
| dodobirdlord wrote:
| The amount of lithium required for these purposes is
| absolutely trivial.
| baking wrote:
| The fuel is deuterium, lithium, and a smaller amount of
| beryllium or lead used as a neutron multiplier to assure a
| net positive tritium production. Yes, tritium is needed to
| start the reactor, but it can be replenished with lithium
| tritium breeding in the blanket.
|
| Deuterium is plentiful in tap water.
| rory wrote:
| The fuel for fission comes from rocks. The Earth is full of
| rocks!
| pfdietz wrote:
| That's actually a reasonable argument if you have
| breeders. The U and Th in an average continental crustal
| rock will give that rock 20x the energy output of burning
| the same mass of coal.
| hutzlibu wrote:
| It's like saying the ocean is full of gold for anyone to
| pick up. It is. But not worth picking up with the very low
| concentration.
| Krasnol wrote:
| You don't need an astroturf.
|
| Nuclear ruined it's own reputation for generations though
| hopeful not as long as they'll have to care for the waste we
| already have.
| UnFleshedOne wrote:
| What ruined nuclear reputation is environmentalists who
| don't actually care for environment.
| Krasnol wrote:
| Parroting Shellenberger will never make you look like a
| serious participant in this discussion.
| UnFleshedOne wrote:
| Haven't read his books, I must have gotten his ideas by
| osmosis. Now reading criticism of the books on his wiki
| page, I think his critics are not concerned with
| environment any further than it aids their real case if
| the quote below is a representative sample:
|
| "criticizing [The Death of Environmentalism: Global
| Warming in a Post-Environmental World] for demanding
| increased technological innovation rather than addressing
| the systemic concerns of people of color."
| Krasnol wrote:
| You don't have to read his books these days since the
| Astro-Turf he's fuelling with those phrases is all over
| social media.
|
| I won't even go into this baseless bashing of
| "environmentalists". It's cheap and disgusting. Some of
| them have dedicated their whole life to the cause while a
| shitty anthropologist bashes them while being paid by the
| same companies which pollute the planet.
| ncmncm wrote:
| What ruined nuclear's reputation is corruption, and being
| the most expensive choice. (Although coal will end up
| overwhelmingly more costly, in the end!) Would it be so
| expensive without corruption? Who can say? Corruption is
| wired into the process.
|
| We are purely lucky that, for structural reasons,
| corruption is minimal on solar and wind projects.
| Probably this is because what it ought to cost is readily
| visible from the outset. There just isn't enough fat to
| attract graft.
| UnFleshedOne wrote:
| Yeah, most expensive choice, unless you count
| externalities of coal.
| soperj wrote:
| It wasn't a joke, it was always based on an adequate level of
| funding. Everything is always off in the future if it never
| gets funded.
| JackFr wrote:
| Ah yes, and how much money? The answer always seems to be
| "More".
| MauranKilom wrote:
| Please consult this graphic from 1976 if you are actually
| interested in the answer.
|
| https://i.imgur.com/3vYLQmm.png
| drdeca wrote:
| Could you clarify how to read this chart? The y axis is,
| funding given different plans? Or.. I got the impression
| that this is meant to depict a relationship between when
| practical fusion would be developed and how much funding
| it receives, but I don't see how to get that from the
| chart.
|
| Also, not sure why imgur has that image marked as adult
| content.
| MauranKilom wrote:
| These are projections made in 1976. They can be read as
| different project plans made at that time for different
| amounts of funding. For example, "if we follow the blue
| plan, it would require 9 billion (2012) US dollars of
| funding in 1982 (etc.) and we would achieve fusion by
| 1990."
|
| The 1976 projection was that, assuming funding was kept
| at the level of 1976 (~1 billion a year), fusion would
| not be achieved in the foreseeable future. It further
| shows that actual funding has been _below_ that level.
|
| In short: Yes, getting fusion off the ground sooner would
| have required more money. Not "always more", but more
| than "we project no success" levels.
| pfdietz wrote:
| Those plans would not have worked, though. They were for
| programs that assumed tokamaks worked better than they
| actually do. And by the 1980s it was realized (Lidsky;
| Pfirsch and Schmitter) that heat transfer limits would
| make any tokamak power plant unattractive.
| apendleton wrote:
| I mean, yes, obviously if the criticism is that they're
| getting too little money, clearly they want more. Some
| technologies are fundamentally expensive to develop (the
| Apollo program, the Manhattan project, etc.). That
| doesn't mean the people saying so are automatically
| charlatans, especially given that they've never gotten
| what they've asked for -- it's not like some bomber
| development project where they get what they want and
| then keep coming back for more. The relatively paltry
| amounts the US has been devoting to fusion energy
| research are lower than any of the scenarios laid out in
| a 1976 DOE planning document[1] about what it would take
| to achieve fusion power, and lower even than just
| continuing at 1970s levels (a plan they labeled in that
| document as "fusion never").
|
| [1] https://books.google.com/books?id=KSA_AAAAQBAJ&lpg=PA
| 234&ots...
| AnimalMuppet wrote:
| Per a comment by nielsbot, they're saying 2025. So, four
| years away, not 20. That's progress...
| ncmncm wrote:
| There will be no need for NIMBY: fusion power is necessarily
| 100x+ more costly than solar + storage.
|
| The only real open question is how long the gravy train will
| run before the plug is pulled. F-35 and SLS have demonstrated
| that with careful management, that can be longer than anyone
| could have believed.
| nixass wrote:
| "Fusion is always 50 years away" for a reason
|
| https://www.reddit.com/r/Futurology/comments/5gi9yh/fusion_i.
| ..
| pfdietz wrote:
| With respect to that graph: tokamaks turned out to not work
| nearly as well as the plans embodied there assumed (and
| because engineering obstacles were not sufficiently
| publicly acknowledged at the time). If funding has not been
| as high as hoped, it's because stakeholders don't really
| exist for fusion. The utilities have never thought much of
| it.
| MisterBastahrd wrote:
| Fusion is the Linux Desktop of energy projects.
| TheGoddessInari wrote:
| Will fusion also occur then due to the mishandling of
| Windows 11?
| cletus wrote:
| I've long been skeptical of ITER making any sense given its
| insane cost. I mean even it succeeds, then what?
|
| Here's the truth: there's no such thing as free energy. Even if
| the fuel is so abundant it's actually or effectively free (eg
| deuterium), the energy isn't. Say it takes $50B to build a plant
| that produces 1GW of power, which I'll estimate at about
| 7TWh/year based on [1]. Let's also say it has a lifespan of 40
| years and an annual maintenance cost of $1B going to up to $2B in
| the last 10 years.
|
| So that's 40 years for 280TWh at a cost of $100B, which equates
| to $0.35/kWh if my math is correct.
|
| I realize ITER isn't a commercial power generation project. My
| point is that people need to stop getting hung up on the fuel
| being "free". The lifetime cost of the plant can still make it
| completely economically unviable.
|
| Second, the big weakness of any fusion design is neutrons. The
| problem people tend to focus on is that neutrons destroy your
| (very expensive) containment vessel with (one of my favourite
| terms) "neutron embrittlement".
|
| As an aside, hydrogen fusion also produces high speed helium
| nuclei, some of which tend to escape and this is a problem too
| because Helium nuclei are really small so can get in almost any
| material, which is a whole separate problem.
|
| But here's another factor with neutrons: energy loss. High speed
| neutrons represent energy lost by the system.
|
| To combat these problems we've looked for alternatives to
| hydrogen-hydrogen fusion, the holy grail of which is aneutronic
| fusion. The best candidate for that thus far seems to be Helium-3
| fusion but He-3 is exceedingly rare on Earth.
|
| I really think we get caught up on the fact that this is how
| stars work but stars have a bunch of properties that power plants
| don't, namely they're really big and they burn their fuel really
| slowly (as a factor of their size), which is why they can last
| billions or even trillions of years. Loose neutrons aren't really
| an issue in a star and sheer size means gravity keeps the whole
| system contained in a way that magnets just can't (because
| neutrons ignore magnetic fields).
|
| So I hope they crack fusion but I remain skeptical. Personally I
| think the most likely future power source is space-based solar
| power generation.
|
| [1]: https://en.wikipedia.org/wiki/List_of_largest_power_stations
| nickik wrote:
| While I agree with your point about ITER.
|
| Space based power generation to me is incredibly dumb. It would
| be far easier to build solar on earth and transport it around
| with high efficiency DC lines.
|
| And if you are really looking into the cheapest possible energy
| a thorium breeder reactor could run for ever with no fuel cost
| and could be built with 70s technology. These reactor be
| produced in a factory at a manufacturing line and then dropped
| into a containment facility.
|
| How this should be more expensive then space based solar makes
| no sense to me.
| sdenton4 wrote:
| If only there were some way to capture and use all that power
| from the giant fusion reactor in the sky...
| gibolt wrote:
| Your numbers sound like generation 1 numbers, after ITER. ITER
| is only a test facility to prove _hopefully_ that it can be net
| positive.
|
| However, those maintenance costs (your estimates) would be the
| first thing to drop. Any company producing/operating these will
| be competing with wind and solar, and thus highly incentivized
| to improve. There should be plenty of low hanging fruit, since
| it hasn't happened once yet.
| ncmncm wrote:
| Maintenance cost is not a place to expect major cost
| reductions. Those tend upward.
| mLuby wrote:
| It seems you're suffering from "neutron embitterment." ;P
|
| Space-based solar power generation (itself "fusion power" in
| the loosest sense) would be great in the inner planets.
|
| Though to open up the outer planets, Kuiper belt, Oort Cloud,
| and any other stars, we'll need non-solar* power: hopefully
| fusion, at least fission.
|
| *Unless we want to go the stellaser route, but I'd bet we'll
| crack fusion before getting near K2.
| ncmncm wrote:
| It won't be Tokamak fusion in any case. FRC (burning D+H-3)
| might work, but there is no money for it. Neutron-emission
| fusion eats all the fusion money.
|
| H-3 is not nearly so scarce as _cletus_ suggests. It is
| uncommon, but you don 't need much.
| snek_case wrote:
| Once we've shown this can work successfully, I think people
| will get excited and investment money will rush in. Ideally,
| we'll perfect the technology and make it cheaper and more
| efficient, just like any other technology. If an MIT-borne
| fusion startup IPOs and they have a working demonstration
| reactor, I would probably invest.
|
| I think the hope is that with economies of scale, we could
| build really huge fusion plants one day, and drive down the
| cost of energy to less than a cent per KWh, and of course
| completely eliminate our dependency on fossil fuels. If energy
| becomes that cheap, we could use electricity to produce
| hydrocarbons from CO2 and water to power airplanes and such.
| Currently, we can imagine short-distance flights being
| electrically powered, but transatlantic flights are going to be
| difficult to achieve with batteries.
| fnord77 wrote:
| so what is the most feasible approach? NIF's inertial containment
| or mini-tokamak?
| nickik wrote:
| As a society we have failed to really use fission. Fission does
| basically everything fusion promises to do.
|
| Fission has a absurdly high energy density, the step from oil to
| fission is far more relevant then the step from fission to
| fusion.
|
| Fusion would mean basically no fuel cost, but thorium is already
| a waste product and even uranium fuel is a tiny part of any
| fission plant.
|
| Some people seem to believe the fusion is inherently prove
| against weapons, but this is equally not really true. If you had
| a working fission plant there would be ways to use it to get what
| you want to make a weapon.
|
| There are some places you might want fusion, mainly in space
| travel but even there we are not anywhere even close to where we
| could get to with fission. Open gas nuclear thermal rockets
| anybody?
|
| In sum, I'm not against this reseach but its not a way to solve
| our problems anytime soon. Fission you could get to run with 60s
| tech and amazing reactors could be designed within decades and
| often with comparatively small teams in the 60-80s and somehow we
| haven't managed to make it competitive.
|
| Fusion looks to be far more complex to build in every possible
| way. How this will be cheaper is questionable to me.
| Seanambers wrote:
| If anyone have not seen it i recommend this video as a primer for
| fusion technology, it's from MIT.
| https://www.youtube.com/watch?v=L0KuAx1COEk
|
| The video thouches upon magnetic fields and its relevance at this
| time mark ; https://youtu.be/L0KuAx1COEk?t=2880
| freeopinion wrote:
| Let me know when the advance comes from Elizabethtown Community
| and Technical College. That would probably be affordable to put
| in production.
| sc0ttyd wrote:
| The claim is that they have reached "a field strength of 20
| tesla, the most powerful magnetic field of its kind ever created
| on Earth"
|
| Haven't Tokamak Energy in the UK done better than this already
| back in 2019 with their 24T magnet based on similar HTS tape
| technology?
|
| https://www.tokamakenergy.co.uk/tokamak-energy-exceeds-targe...
| bawana wrote:
| If you compress something so much that its nuclei want to fuse,
| it must become very dense. At the core of this compression,
| density is intense. Unlike a thermonuclear weapon where the
| compression is transient, there is no release from this nuclear
| vise. Pressures would radically rise increasing compression even
| further. Would the gravitational field in the vicinity of the
| center of this be equally intense? Could black holes on the order
| of the Planck scale be created? Would such a 'Planck hole' start
| a chain reaction of gravitational collapse, eventually growing to
| consume our solar system?
| kgarten wrote:
| Better title: Startup builds strong magnet that might be useful
| for a fusion plant.
| phtrivier wrote:
| I hope the researchers behind this are proud.
|
| And I hope the marketers pretending they'll have a commercial
| plant by 2025 are ashamed.
| marsven_422 wrote:
| Fusion is a distraction we can not afford, it creates the same
| low level waste as fission and we have plenty of fissionable
| material available.
|
| Massive international expansion of fission energy is needed for
| humanity to prosper.
| criticaltinker wrote:
| The advances enable a magnetic field strength that would
| otherwise require 40x more volume using conventional technology -
| doesn't the reduced volume imply the plasma temperature would
| also increase significantly? Or is the magnetic field strong
| enough to protect the walls of the chamber?
| tppiotrowski wrote:
| My understanding is that the volume of the magnet is smaller
| and thus the entire reactor size goes down significantly
| leading to lower cost.
|
| ITER was designed to use weaker electromagnets and therefore
| needs a massive building and tons of cranes and a massive
| budget.
| pfdietz wrote:
| The ARC reactor design has 10x the volumetric power density
| of ITER.
|
| Unfortunately, the ARC design also had 40x worse power
| density than a PWR primary reactor vessel.
| apendleton wrote:
| Is that the right metric? You wouldn't need to build a huge
| containment structure around it like you would for a PWR,
| so I'd imagine the power density of the plant as a whole
| wouldn't be anywhere near 40x worse. Why focus just on the
| primary reactor vessel?
| pfdietz wrote:
| Because the rest of the power plant will be similar (or
| also worse for fusion; consider the tritium handling
| facility or the robotic equipment for maintaining the
| fusion reactor). You would need a confinement structure,
| just to keep the tritium in (which will leak all over
| even in normal operation). So if you swap out a cheap PWR
| reactor for a much larger, and hence much more expensive,
| fusion reactor, you get a power plant that costs more
| than a fission power plant.
|
| Viewed another way: if you could make a fission reactor
| with a power density as low as ARC, it would have so much
| thermal inertia that meltdowns would be essentially
| impossible. You should then ask why such fission reactors
| are not built.
| apendleton wrote:
| I guess I still just don't really see it... like, coal
| plants are also much less energy-dense than nuclear
| fission. So is solar, so is wind. We build all of those
| anyway. There are lots of things other than power density
| that contribute to whether or not a particular generation
| technology is economical.
|
| As to why massive fission reactors aren't built: there
| are plenty of already-available passively-safe/meltdown-
| proof fission designs (many gen-IV designs qualify), and
| from what I can tell, the reasons they're not built are
| as much political as anything -- people don't like them,
| and the consequent regulatory regime has made any fission
| projects prohibitively expensive regardless of their
| size. None of this need be the case with fusion.
|
| As to tritium: I think you're overstating the tritium
| risk. They're only dealing with grams at a time, and even
| if it all leaked out, it would rapidly diffuse such that
| risk to the public would be infinitesimal as compared to
| normal background radiation (plus its half-life is only
| something like 12 years). ITER has a safety page:
| https://www.iter.org/mach/safety that essentially says as
| much.
| pfdietz wrote:
| Power (not energy) density matters in comparison of
| fission and fusion because the rest of the power plant is
| very similar. It's not relevant to the comparison of PV
| solar and fusion because this is not true. But we don't
| need to make that comparison, since we CAN compare those
| directly with fission by looking at actual costs, and
| then conclude they should be cheaper than fusion (because
| that will be more expensive than fission).
|
| Tritium will be handled in such large quantities in a
| fusion reactor that even small leaks will be problematic.
| As I like to point out, the tritium made and burned in a
| 1 GW(e) DT fusion reactor in one year would contaminate 2
| months of the entire flow of the Mississippi River above
| legal limits for drinking. Even small leaks could cause
| serious harm to property values (sorry, your ground water
| can't be drunk for the next 50 years.)
|
| Gen-IV reactors aren't built not for political reasons,
| but because nuclear has become such an economic orphan
| that there aren't stakeholders to drive the construction
| of these things. The money isn't there because the ROI
| isn't there.
| mzs wrote:
| SPARC yttrium barium copper oxide (YBCO) high temp (10-70K)
| superconducting magnets
| m3at wrote:
| A bit off-topic but it feel like the right time to ask, does
| anyone recommend some video or even book to understand the fusion
| space better _as a non-physicist_?
| HPMOR wrote:
| Honestly, fission has been the solution for the past 70 years.
| We, as a society, have just failed to implement it.
| joelthelion wrote:
| Could these be used to build MRI machines?
| spoonjim wrote:
| MIT is also the origin of Transatomic Power which went belly up
| after they discovered that an early math mistake meant that their
| whole plan was bunkus, so evaluate this on its own merits rather
| than assigning any halo points from the MIT name.
| pcj-github wrote:
| If we had "an inexhaustible, carbon-free source of energy that
| you can deploy anywhere and at any time" we'd wreck the planet
| faster than we already are... I guess at least a few could escape
| though.
| maccam94 wrote:
| I'm curious whether we could cool the planet by pulling CO2 out
| of the air with scrubbers powered by fusion reactors, or if
| their heat output would cancel it out. Removing the CO2 would
| have the benefit of being an exponential thermal decrease (the
| planet gets less hot from the sun each day), and heat output
| from fusion plants should scale linearly with the rate at which
| the CO2 scrubbers run, so it's possible the scaling properties
| would work out...
| sprafa wrote:
| Unfortunately I predict that when we "stop" global warming
| will likely be when we stop changing the climate (at least in
| that way).
|
| This is because a lot of rich countries seem to me to be well
| placed to benefit partially from global climate change at the
| moment, at least within the 1-2C range. Changing the climate
| past that point is likely to be controversial, since the
| countries who now benefit from the situation will likely not
| want to give those newfound advantages away.
|
| I would think of it a lot as the end result of a war - the
| borders are defined by where the armies stopped ie the
| division of Europe and Asia after ww2. After climate change I
| expect whoever has benefitted from it to defend their
| position and reject any further alterations!
| ncmncm wrote:
| Since power from a fusion plant would cost 100x+ what solar
| and wind cost, no.
|
| But every cent diverted to fusion from solar brings climate
| disaster closer.
| gfodor wrote:
| Do you have a reason to believe capital deployed to fusion
| would have been deployed to solar? And if so, why do you
| think it would make a difference, given the market feedback
| loop going on with solar driving down costs?
|
| Edit: also, your comments seem to be incredibly negative on
| fusion, would you mind disclosing if you have any solar or
| wind connected conflicts of interest?
| ncmncm wrote:
| I have no money invested in solar, wind, or storage
| enterprises. To my shame.
|
| My beef with fusion is about long-term hucksterism and
| wholly-legal corruption. STS, SLS, F-35, Big Dig, 2nd
| Ave, Cal bullet train, fission, fusion.
|
| Dollars are fungible. Would fusion dollars otherwise go
| to renewables build-out? They might be more likely to go
| to battery, solar panel, superconducting power
| transmission, or carbon reclamation research. All of
| those would be welcome alternatives.
|
| Even FRC fusion would be a better use of funding.
| [deleted]
| garbagecoder wrote:
| It just a decade away!!
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