Nuclear fusion is probably still decades away. But I am going tangent here, nuclear fission still have great potentials.
Scientists from the Oak Ridge National Laboratory actually
helped China to built Molten Salt reactors in the 70s during Nixon administration. [1] And since then thorium based molten salt Gen IV reactors have been having renewed interests around the global. China actually tested the whole system feasibility in Giga Watts scale in recent years. [2]
Nuclear power is vital part of the energy infrastructure to curb worsening environment due to climate change - it's still considered superior than all the other green alternative energies in terms of either 24/7 availability (vs. solar/wind) or massive scale (vs. geothermal) or location restricted (vs. hydro) or carbon-free (vs. biomass/bio-fuel). China realized that in their dire request to transition out their entire energy reliance on carbon-based energies, it's impossible to do without nuclear.
Also, newer reactor designs are much safer and last longer so a lot of the concerns of radioactive waste have largely been alleviated.
There have been a series of breakthrough in helicity injection techniques and the understanding of spheromak physics in the last decade. Some believe that economical fusion power plants are possible with today's technology[1] and need a ~$30 million to prove out a scale model reactor before building a full scale one on the order of $2-3 billion of a 1-2 Gigawatt power plant.
This is an order of magnitude less cost that the ITER project, which is spending a lot of money on cement and magnets on a probably doomed technology path of commercial fusion.
These same breakthroughs are also likely to be able to produce a fusion engine for spacecraft. This is actually an easier problem to solve than electricity generation as the deuterium can be used as fuel and as a propellant ejected straight out of the plasma core at variable ISP up to around 100,000. No inefficient fusion to electricity to rocket engine cycle is necessary.
I am not a fusion scientist, but my father is. For more info and technical references, drop me an email (see profile).
> This is actually an easier problem to solve than electricity generation as the deuterium can be used as fuel and as a propellant ejected straight out of the plasma core at variable ISP up to around 100,000.
Jesus.
For reference, chemical rockets tend to have ISP in the low-to-mid hundreds, and ion thrusters are in the thousands—not ten thousands, but single thousands. A 100,000 ISP rocket is like a car that can drive from Bangkok to Vladivostok to Lisbon, then back to Istanbul and down to Johannesburg without refueling or recharging. It’s like a phone battery that lasts years rather than days. And it’s all powered by the most plentiful elements in the universe.
I’m pretty sure you could generate electricity by flying this rocket around in a circle tethered to an electric turbine if you wanted to. I mean, all of your electricity would probably be in space, because a high ISP usually implies that the rocket doesn’t work as well on the earth’s surface (not as a physical law, just as a limitation of our technology), but of all the monumentally impressive things you can build from a fusion reactor, a 100k ISP rocket has got to be up there.
As for ITER, I’m not necessarily bearish on it, but if there’s a credible chance of an alternative design that can be proven for anything <$1 billion...I hate to say it, but any person, venture capital fund, or government with more than $10 billion to their name would be hard pressed to find any better use for it. Even if the damn thing is 95% likely to fail, that’s a 5% chance you literally end up having a stake in the single most valuable technology in the single most valuable sector of the economy—one that will provide untold benefits to mankind.
30 million dollars, really? Like—does Y Combinator know about this? Never mind the “benefits to mankind”—if a single business can be first to market with an economical fusion power plant, that will become the single most valuable business in human history. There’s like five tech companies that are up there in the ranks of “most valuable business in the world”, and they’re approximately the same value as any of about ten oil and gas conglomerates, and those lists usually don’t even count state-owned companies that are even more valuable. (“All the oil in Saudi Arabia”—that’s wealth.) Fusion power would immediately be more valuable than every single oil and gas company in the world put together. Even if nobody bought fusion plants, you could just build the damn things yourself, use them to synthesize hydrocarbons from the damn atmosphere, and undercut the market while simultaneously fixing climate change by making fossil fuel usage a closed loop with no new net CO2 introduced into the atmosphere and an economical method for extracting the excess we already have.
For reference the temperature of fusion plasmas are in the 100 million degrees C range. So very high ISPs are not that crazy. There are many other problems to solve in building a usable fusion rocket, but high ISP comes for free.
One thing you should realize about a fusion reactor is that the easiest (which is still really difficult to do) reactions for fusion release a lot of their power in neutrons. These can not be harnessed directly to produce electricity, unlike moving electrons or ions theoretically could be. They can be used to boil water, just like a coal plant, and use steam to run a generator to make electricity. This part of the power plant is expensive. And the fusion reactor is expensive. You don't just get a Mr. Fusion on your car roof outputting Gigawatts of power.
As to it being a great investment, an electric power generation method is only going to be a great one if it is much cheaper than current methods. This is why ITER is such a boondoggle with its $10-$20 billion dollar price tag. It is very unlikely to be the path to putting fusion power onto the grid. Also, who knows if people will be just as afraid of nuclear fusion plants and nuclear fission. If that is the case they will not be economical to build. Maybe a name change is in order?
Relativistic magnetohydrodynamics is a hard subject matter. Investors with $30 million dollars to speculate on such a project are not going to know enough to distinguish a possible project from unlikely ones. Physicists who can know enough to see that some plan might work are unlikely to have the funds to invest. I saw Sam Altman had a fusion book on one of his lists at one point and Elon Musk might know a physicist he would trust, but getting those people to take a look is not easy. I'd be happy to make introductions though. :)
> One thing you should realize about a fusion reactor is that the easiest (which is still really difficult to do) reactions for fusion release a lot of their power in neutrons. These can not be harnessed directly to produce electricity, unlike moving electrons or ions theoretically could be. They can be used to boil water, just like a coal plant, and use steam to run a generator to make electricity. This part of the power plant is expensive. And the fusion reactor is expensive. You don't just get a Mr. Fusion on your car roof outputting Gigawatts of power.
I would kind of expect a completely new technology to be expensive to begin with.
> As to it being a great investment, an electric power generation method is only going to be a great one if it is much cheaper than current methods. This is why ITER is such a boondoggle with its $10-$20 billion dollar price tag. It is very unlikely to be the path to putting fusion power onto the grid.
I'm not sure how that follows--this might not be a great comparison, but the cost of building the first two atomic bombs was orders of magnitude higher than the cost of building the most recent two atomic bombs. Even if it costs $20-50 billion dollars per fusion power plant, it still might work out if each plant can produce enough economy of scale.
> Relativistic magnetohydrodynamics is a hard subject matter. Investors with $30 million dollars to speculate on such a project are not going to know enough to distinguish a possible project from unlikely ones. Physicists who can know enough to see that some plan might work are unlikely to have the funds to invest. I saw Sam Altman had a fusion book on one of his lists at one point and Elon Musk might know a physicist he would trust, but getting those people to take a look is not easy. I'd be happy to make introductions though. :)
Yeah, that makes sense. There has to be some reason that a $30 million plan to build a proof-of-concept viable fusion reactor hasn't been funded yet.
Tokamak fusion plants 10 times the output of the biggest power plants today are likely to work, but no one would want such huge plants on the grid. When it needs to shut down for maintenance, that amount of power cannot be easily replaced. If it was used only for hydrocarbon synthesis, hydrogen generation, or seawater desalination, this could work, but not for electricity generation.
> Tokamak fusion plants 10 times the output of the biggest power plants today are likely to work, but no one would want such huge plants on the grid. When it needs to shut down for maintenance, that amount of power cannot be easily replaced. If it was used only for hydrocarbon synthesis, hydrogen generation, or seawater desalination, this could work, but not for electricity generation.
The United States has, according to a quick Google, over 8,000 power plants. If you replaced them with 800 fusion plants, wouldn't you still have enough redundancy to take them offline for maintenance? Sure, having a smaller number of power plants increases line loss, but there has to be some economy of scale where tokamak fusion starts winning.
Thinking even bigger, if you have a 100x or 1000x scale fusion plant and used it for hydrocarbon synthesis, as you suggest, couldn't you use that plant to supply several downstream power plants that burn hydrocarbons and still, potentially, end up net-ahead?
I dunno--my impression is that the theoretical yield of fusion is so high that you can very, very quickly start reaping benefits even if you're doing so in extremely inefficient ways. Once you get above break-even, even if you're only a couple percentage points above break-even, if can build a huge enough reactor, it adds up really, really, really fast. Fast enough that some rich technocratic dictatorship could, say, build a bunch of tokamaks and effectively corner the world oil market without drilling for a single barrel of natural oil. You'd have to think that fusion starts doing things to the cost of energy that Moore's Law did to the cost of computing, to the point where people actually wrap user-facing applications in gratuitous web browsers.
You still have the cost of steam turbines and generators just like a coal/oil/gas power plant. The main cost savings is the fuel cost, which is a small but significant fraction of today's electric power cost.
There are theoretical proposals for direct conversion of electricity using the charged particles of certain fusion reactions (usually using Helium-3 mined from the moon) in different reactor designs but those are even further out than the toroidal magnetic confinement reactors (tokamaks, spherical tokamaks, and stellarators.)
I know it is really hard to believe that if fusion power was possible we as a society would just not choose to develop it, but that is the case. This philosophy/issue is discussed by many people, in many contexts and can be summarized by Peter Thiel's quote, "We wanted flying cars, instead we got 140 characters"[1]. The world had been on a runaway upward trajectory of technological improvements that peaked with the atomic bomb, nuclear power, and the Apollo program and then basically stopped.
In the 1970's a huge demographic block started coming into power, the baby boomers, and for many different reasons they questioned all of this ever increasing "improvements". Humans seemed not to have enough wisdom to wield wisely the new levels of power tech improvements were giving them. The Vietnam "war" against a country that never attacked the USA, DDT and other pesticides were killing all the bugs and destroying natural ecosystems, Russia and the US were building up an arsenal of nuclear weapons that numbered in the tens of thousands and could destroy humanity in 15 minutes, nuclear power was getting started and promised to give us electricity too cheap to meter to fuck up the planet even quicker, we kept tearing down and cutting apart beautiful cities with more and more interstate freeways, modern architecture with its anti-human scale and design, Agent Orange, etc. It was probably a good idea for humanity to take a breather on improving tech. The geeks were denied the power to keep implementing more powerful tech and nuclear powered rockets and airplane research were shut down. Denied working with real world, geeks turned to computers and no one cared. How could one do anything scary with pure calculations?
Well, whole libraries full of books have been written on the subject. For power generation just look at how it is priced for residential costumers. In California the price per kWh goes up the more you use, unlike almost any product. Our philosophy on power generation in the "tech capital of the world" is that we should do less of it, not more. Cheap power is a negative thing. It takes a strong sense of purpose to invest large amounts of money into a project that your peer group is going to say is a bad thing.
As the boomers fade from power, I see some hope of humanity too gain back some of its dreams for a better future using more powerful tools but with more balance on keeping things good for humans. Elon Musk is a good example for a third way, I hope.
Big power plants are a problem. The US generating capacity is about 1,000 Gigawatts [2] so if fusion power plants are huge at 20 Gigawatts, that is only 50 plants. One per state. You can see how one of those going down is going to be a problem. The average plant size is only 0.06 Gigawatts if your 8000 power plant number is correct. (All calculations liable to correction as this is just a quick web comment.)
> The geeks were denied the power to keep implementing more powerful tech and nuclear powered rockets and airplane research were shut down. Denied working with real world, geeks turned to computers and no one cared. How could one do anything scary with pure calculations?
Hah! Still, I don't think this is a total loss. Sure, we use computers for a lot of dumb stuff, but we also use them to cure cancer, control rockets, design airplanes, find our way when we get lost, produce art, and distribute information. And there was so much low-hanging fruit in computing that this focused effort let to outsized economic growth and basically brain-drained the entire rest of our society.
> Our philosophy on power generation in the "tech capital of the world" is that we should do less of it, not more. Cheap power is a negative thing. It takes a strong sense of purpose to invest large amounts of money into a project that your peer group is going to say is a bad thing.
> As the boomers fade from power, I see some hope of humanity too gain back some of its dreams for a better future using more powerful tools but with more balance on keeping things good for humans. Elon Musk is a good example for a third way, I hope.
It's not entirely clear that this cynicism will die with the baby boomers. They've had decades to instill and pass down their pessimistic attitudes while the hope and enthusiasm that took us to the Moon gradually passed from cultural memory. Even now, the most audacious project that the average millennial can think of is a "Universal Basic Income" so he gets a lifelong stipend to sit at home playing video games.
Musk is a good example of a way forward, but if anything, his story proves my point. Musk is an optimist and someone who actually believes in the American Dream, and it's no coincidence that he's also an immigrant. Optimism and ambition used to be the defining qualities of this country. Someone who believes in them strongly enough to come here usually believes in them more strongly than most of us who were born here. (Probably a corollary to the old observation that recent converts to a religion are more obnoxiously pious than those born in it!)
But America still has enough optimists, and if there ever is a small-scale fusion reactor design that gets proven feasible, it's a lot easier to convince the last surviving well-funded ambitious optimists than to convince the greater public. And if we the West doesn't make it out of this hole, there are still other hungry up-and-coming civilizations out there in the world who will get around to it in due time themselves.
Is this really only a networking issue, a matter of people with the right information being unable to reach people with the right amount of capital to invest? Sounds pretty unlikely, but if so, that's insane.
It's quite misleading to talk about 100,000 Isp for fusion. That's because unless the quantity of material you are expelling is at least as large as the fixed mass of your engine and tankage, high Isp actually hurts you. You'd be better off diluting the outgoing mass with inert material and accepting a lower Isp, but higher total impulse delivered by the stage.
How much fuel do fusion reactors burn?
A 1 GW(th) plant will burn about 100 kilograms of fusion fuel per year. ITER, which has a mass of 23,000 tonnes, will produce 400 MW(th). So, going by that, it would take nearly a million years for a reactor like ITER to fuse its own mass in fusion fuel. That's obviously silly. ITER is clearly not optimized for use in space (and burns DT, in which 80% of the energy comes out as neutrons that are useless as plasma exhaust), but any real fusion rocket will be designed to operate with an Isp much lower than 100,000 seconds.
Agreed. That is why I said variable up to around 100,000 ISP. For low thrust application having high ISP is great for saving propellant. The key feature for a fusion rocket is that one can have tanks of deuterium as the propellant you can mix into the plasma that is also the fuel.
I think the general public has just completely given up on seeing any kind of new, radical cool tech but with the decline in the anti-tech baby boomer generation a lot of progress of long dreamed projects are starting to happen. SpaceX has lead the way with reusable rockets.
Here is a link to a video from a real company that is actively researching and building fusion rocket prototypes[1].
That's a little reassuring in the sense that 100,000 Isp is, by at least an entire order of magnitude, too good to be true.
But, who knows? Energy is such a limiting factor that maybe you could, with enough energy, make a gigantic space-ark in space and fill it with hydrogen and have a massive fusion-powered rocket with 100,000 Isp. Maybe that's how we reach Alpha Centauri.
One huge problem with any extremely high Isp rocket is heat dissipation. Any heat hitting the vehicle has to be radiated (there is insufficient reaction mass flow for that to cool the engines, as it does in chemical rockets). So it pays to keep the powerplant separate and beam low entropy energy at the vehicle.
Cheap unlimited energy leads to heat pollution per the laws of thermodynamics. Asimov Foundation series first book warned about this in passing. Be careful what you wish for!
TriAlpha's scheme was roundly criticized 20 years ago (basically, ions scatter much more readily than they fuse, so their colliding beam scheme can't work.) They responded to these criticisms, but in my opinion their responses were inadequate. And now they're pivoting to cancer treatment! It's not difficult to see where this is going to end up.
I'm not a fusion scientist either :) But I was fortunate to sit next to one in a bar in Princeton NJ a couple years ago. The gist of that conversation was in sync with what you said.
Long to short, it's close. Money could help accelerate the research into the necessary details.
They're saying it (might) be the only thing the world needs now, after all the advances it has made up to today, not that it takes $30M to develop it all from scratch.
There is a point at which a single step is enough to win a marathon; that doesn't mean it would have been enough when the race started.
I wrote that sentence in a 10th grade report on fusion, in 1977. Disappointing that it's likely still true four decades later. In another four decades it's up to you to make this comment.
On the other hand, so much has arrived that I never dreamed of in high school, though I consumed scifi obsessively. Not sure I'd swap the internet for cheap fusion energy. But not sure I wouldn't.
Note that we've never spent as much money as we've always known would be necessary to achieve useful fusion power, so the oft-repeated idea that it's been surprisingly technologically difficult is not actually justified by the historical track record.
> Typically, outsiders cannot comprehend how the massive expenditures never manage to yield energy. Typically, insiders cannot comprehend how little is being invested in a project that presents such immense technical obstacles and also such potential. A graph commonly passed around among the insiders—an enduring scrap of twentieth-century budgetary ephemera—depicts the 1976 federal plan to build a working thermonuclear reactor. The graph tracks various scenarios for attaining fusion energy. The “maximum” effort, the most expensive up front, with initial spending as high as nine billion dollars a year, was projected to yield a reactor by 1990. The “moderate” effort, with spending never exceeding four billion dollars in a year, would take fifteen more years. The fusion community might be easy to criticize for its many unmet milestones, but for decades the United States has never come close to even the moderate effort. In 1977, when the American fusion budget was at its peak, government investment in the research, adjusted for inflation, was seven hundred million dollars; by 1991, this had fallen by more than half. It is now half a billion, not appreciably more than the Korean budget.
The chart was produced by Energy Research and Development Administration (ERDA), which was later subsumed into the Department of Energy and presumably represented the expert wisdom at the time. It can be found, in 1976 dollars, as figure 1 here:
If you take the amount of money they’re asking for, take the value of inventing fusion power (which is enormous), and then apply a very conservative and pessimistic low probability of success, I’m not sure there’s much that has a higher expected value than investing in fusion power.
Funding was reduced from those projections because they were for from a crash project that assumed tokamaks would work really well, much better than it turned out they did.
And in hindsight, even given optimistic plasma assumptions, fusion reactors would have been limited by materials and heat transfer issues. These render any DT-burning reactor problematic, independent of the details of confinement.
Yes, the fundamental idea that $X spent will result in Y scientific knowledge and Z technological advances is managerialist wish-fulfillment. Science and engineering aren't remotely that predictable. We can imagine that we know what we need to discover in order to accomplish something, but the universe likes to laugh at us.
The talking-point that keeps coming up about fusion spending ignores the context that the planned spending was based on a technology that wouldn't have gotten us practical fusion, anyway.
If that $X had been spent, fusion boosters would be complaining about the debacle of wasting all that money on tokamaks and how that undermined fusion research. And if we spent a newly-calculated $X and, years later, still didn't get fusion, the complaint would be exactly that managerial whinge that we just hadn't shoveled enough money down the hole (or down the right hole).
Interesting to note that “tech X is decades” away is actually a nonsensical statement in itself. If we all agree not to research it, then tech X will never arrive (excepting alien visitation).
Pedantic point but also a reminder to avoid fatalism and that as well as extending R&D times, we can also reduce them (see: Apollo).
If it makes you feel better, it probably isn't anymore. ITER, the reactor in France, isn't set up to be efficient. It is more "Well if we make it bigger it is easier. So let's make it A LOT bigger." There's people trying other ways, but ITER is an effort for "show it is possible" and most people think it is.
That being said, the schedule for first fusion is 2025 and D-T operation in 2035 (just under 20yrs). A lot of competitors think they will be successful (at FIRST fusion, not a generator for public use) before then. It is an interesting race.
This reads like a parody of every thread on nuclear technology on HN or, before it, slashdot.
It’s always „decades away“, but there’s always pebble bed/molten salt/thorium/whatever technology that’s far better, basically functional, mostly free, and only held up by those darn environmentalists/idiot politicians/liberals/oil lobby/NIMBYs/Elton John/…
It feels like the tech community is forever trapped in the science fiction of the 50s, while actual science (and politicians) have created options that, frankly, are far better in every regard, including costs.
A major issue is that people on HN are largely ignorant of nuclear power generation. It's largely a bunch of wikipedia-educated people debating youtube-educated people. So none of the discussions are realistic, because there's probably four people on HN with any real world subject matter knowledge.
There's not the same blind-optimism to solar power generation.
There's not the same blind-optimism to solar power generation.
Well.. it's hard to be overtly skeptical to a form of lower intensity power which works at scale, but lower intensity. The only claims to be rebutted are ones which overstate the pace of improvement to the forseen asymptote.
What's more baffling is the constant jeremiad of hate against solar wind and battery because of prejudice favouring large centrally managed gigawatts. Nobody disputes big lumps of powerstation are good. What we're doing is fighting an ill informed skirmish inside the linear programming and O/R model of future power, rather pointlessly.
I would like nuclear fusion and fission power research to continue. I would like the funding to lower intensity power to continue as well. I would like a grown up conversation about how much each should get annually as funding.
What's similarly baffling to me is the constant jeremiad of hate against nuclear.
Personally I'm a fan of any carbon-free power source. In particular solar and nuclear seem like they'd go together quite well: nuclear baseload, solar for extra daytime demand, and enough storage to handle the remaining discrepancy with the demand curve. (A couple years ago MIT had a grid simulation that let people try out different combinations to see the overall cost, and that was the cheapest I came up with.)
France's costs were always opaque, since they mixed the civilian and military nuclear programs.
In any case, France can not now build reactors cheaply. The recent attempts have experienced disastrous cost overruns (a factor of 3x for Flamanville). New nuclear has failed there just like it failed here in the US.
It's the unavoidable up front subsidy envy. That, and fears of statist controls obligated by unimaginable risks. The actual risks experienced being lower except when corporate greed behaviour goes Fukushima.
Actual power cost and deaths per gigawatts? Unbeatable. I used to hate on nuclear, I changed my mind. End the lawsuits and let's get building again.
That's really true. The issue is probably in natural curiosity within our (this) group. Personally, I don't have much experience outside of two areas of expertise, but I'm curious about many other areas, read about those, sometimes even dabble... but nowhere near the level to 'offer' solutions. Usually the case when you think something is obvious or trivial, you don't understand the problem(s)... usually.
Better in every regard including -immediate- costs, maybe. If we go worst-case climate change in 40 years, not putting massive development into fission and fusion power will clearly become the most costly mistake we've ever made as a species. Yes, we've got some promising renewables, but they are coming in the eleventh hour and it may be too late. We could have nipped this in the bud half a century ago. Your style of reasoning has been trotted out as a common-sense justification not to stave off the literal apocalypse for all those intervening decades, and here we are.
I don't think this can be overstated enough. Yearly budgets and disasters like Chernobyl and Fukushima are important, sure, but they're on an entirely different tier from what we're about to wreak on ourselves. We're evaluating the risk of these technologies all wrong. Accidents and sacrifices would have been worth it. Even nuclear proliferation leading to all-out nuclear war would have been preferable to what we're about to experience. And that is truly harrowing.
Sunlight is ~1kW/m^2. That’s solar aligned area rather than land area, so you need to generate about 10^17 watts before the laws of thermodynamics become something you cannot deal with just by using your astronomical supply of cheap energy to cheaply manufacture and install a sun shade at L1.
It's too late. If we really believe the predictions [0] then we need to go all-in on fission like 10 years ago. Yes, there are risks to nuclear power. I'll take risks of localized disaster over the certainty of a global catastrophe.
Most accept a potential "localized disaster"... as long as they aren't at risk themselves ( https://en.wikipedia.org/wiki/NIMBY ). Always letting the poorest directly assume such risk may be a good recipe for a global social catastrophe.
Regardless, I volunteer for the danger zone. The 99% worst case is merely evacuation, and expensive power plants pay for lots of nice thing with their taxes.
Also insurance is a perfectly viable way to spread out risk so that no group of people is disadvantaged.
The fact that you are not in NIMBY is possible, your arguments, albeit debatable (no insurance company offers any policy related to large-scale nuke risk), are acceptable, but nonetheless you sit in a tiny minority thinking this way. AFAIK everywhere the majority is stuck in NIMBY mode.
If you were going to make a thousand power plants, I bet you could easily create such an insurance.
But people are always going to be unrealistic about risk. So I dunno, ask people if they accept a tiny chance of localized disaster, and then ignore everything they say about their own location.
The poorest in the world are most exposed to the risks of climate change.
Building out nuclear power in developed countries would mean the globally wealthy assuming a fairer measure of the risks associated with their consumption.
If you only count the reactors that are already built and still operating, they are pretty cheap sources of electricity. The old nuclear projects that were abandoned before completion won't be part of your "power per dollar" denominator. The reactors that were shut down 10 years ago because they were too expensive to keep running will also be missing from the denominator. The late and over-budget reactors that have yet to enter service will be missing from the cost denominator as well. Once you limit the field of inquiry to the surviving, operating nuclear plants, they're pretty affordable.
If you interpret the question as meaning "nuclear energy is currently the second cheapest per watt [to add to a nation's electricity supply]" -- no, that's incorrect for anywhere with half-decent wind or solar resources.
The final question that prevents me from being a 100% renewables triumphalist: what happens to the relative cost of nuclear vs. more renewables + storage as renewable penetration rises? Storage is hardly needed at present penetration levels. Only a modest amount of storage (overnight) may be needed for 50% or even more penetration. But what happens at 80%, 90%, 100% decarbonization of the electricity supply? It's possible that even expensive new reactors will be cheaper than reaching 100% with storage and renewables alone. It remains an open question.
As renewables, getting cheaper, are added and longer term storage becomes needed, nuclear is placed in a horrible position.
That's because nuclear needs to sell its power a high percentage of the time or its economics become ridiculously bad.
So what happens when solar/wind/short term storage are covering things 80% of the time, at a cost (during that period) the nuclear reactor cannot come close to, on a levelized basis? The cost of power from the nuke goes up by a factor of as much as five. Nuclear plants are horrible as intermittent fill-in sources. It instead becomes more economical to add low-efficiency long term storage options (like hydrogen) and to just overbuild the intermittent sources.
Yes, nuclear reactors are terrible as peakers. I think that they would make sense mostly to put a floor under worst-case-minimum scenarios for renewable power generation (like "a week-long period of intense winter cold, far from the equator, while wind isn't blowing much.") In that scenario, there would still need to be some long-duration storage system like hydrogen in salt caverns but the storage reserves don't need to be as large as in the 100% renewable scenario. The lower bound on daily generation is higher. Reactors would run at near-constant levels like now, the only difference being that they'd recharge storage systems at low-demand times.
Or it could turn out that building very large storage systems, even capacious enough to e.g. ride through Germany's entire winter, is less expensive than building new reactors. I'm just trying to keep an open mind about a future role for new reactors. I'm pretty skeptical about starting new reactor builds right now. My strongest present opinion about power reactors is that it's a shame to close working units while their attached grids are still consuming fossil combustion power.
The best case for nuclear in the future will be if new designs can reduce the levelized cost of energy to be more competitive with renewables. This requires new designs -- light water reactors can't do it. It will be a long shot in any case. I am favorable to Moltex's SSR, which uses molten salts but avoids some of the more vexing issues typical MSRs encounter.
Small molten salt reactors might also address industrial process heat markets, where they'd have a possible advantage over renewable sources as their heat could be used directly.
"The best case for nuclear in the future" will be off Earth (I hope). High density portable energy sources are a godsend for solar system colonization. Solar and wind on Mars are much worse energy sources than on Earth, especially if you factor in the cost of transport. For a long time the most powerful system per kg is the one to use.
Launching them from the ground is a bit risky though. We can do it reasonably safely with RTGs but with complete nuclear reactors the risk of contamination in a crash is somewhat greater.
Where did you get that information? A reactor that has never been run has almost no radioactivity. Its basically just native uranium metal/oxide. RTGs are a higher risk and more radioactive. It is really a shame that such wrong ideas are so widespread.
It’s also an open question just how many of those costs are real and how many of them are political, regulatory, or otherwise artificial. Maybe nuclear is expensive because we’re making it expensive.
A data point in favor of this: Suppose there was a fast developing country that had the resources and requirement to build more power generation capacity than any other society in human history. Suppose, further, that this country was relatively immune to political concerns because it was governed by a technocratic bureaucracy. Just for the hell of it, let’s imagine that most of the techno-bureaucrats have some sort of engineering background. It so turns out that there is a country exactly like this, and their long term energy policy is to build a massive hydroelectric dam on the one place in their country that is particularly well-suited for it, and then build lots and lots and lots of fission plants and invest in fusion research.
UK: 15 reactors, ~10300 gross MWe. They analyzed and now think that decommissioning will cost £234 billion (309 billion USD).
USA: 98 reactors, 100350 gross MWe. 46 billion USD (Nuclear Waste Fund) are in provision.
One order of magnitude more power produced by the stuff to decommission in the US, and nearly 7 times less money to do so.
Decommissioning small and old reactors costs more, and entombing may, at least apparently (short-term), reduce the cost. In theory. Let's check a real and ongoing case: Oyster Creek. According to the EIA its construction costs were $488 million (2007 USD) ( https://www.eia.gov/nuclear/state/archive/2010/newjersey/ ). As soon as the decommission project started the Nuclear Regulatory Commission announced that it will cost "about $1.4 billion to shut down the plant". Not for an immediate and complete decommission, because the plant will stay in a “safe store” condition until 2075, with dismantling ((...)) set for a period between 2075 and 2078 ( https://www.powermag.com/oldest-u-s-nuclear-plant-shuts-down... ). Then new problems (costs!) may arise. Let's bet that, as usual, the taxpayer will pay.
Long-term waste management is another ticking bomb.
Moreover if there is a serious glitch (Chernobyl, Fukushima...), are bets are off. You can obtain an insurance policy for anything, AFAIK even for a space trip, but no insurance company covers such nuke risk.
Decommissioning the CO2 in the atmosphere is maybe a bigger ticking time bomb? People are irrationally afraid of human created radioactivity.
If they only knew how much they get from bananas, granite counter tops, and airplane trips in comparison to nuclear power and scaled their fear of radiation down to that level, most of these expensive problems would be 100 times cheaper to deal with. How about a massive education campaign about radiation starting in elementary school? Kill the fear. Isn't the whole point of education is that an educated public can make better choices? Let's use that tool.
> China realized than in their dire request to transition out their entire energy reliance on carbon-based energies, it's impossible to do without nuclear. Also, newer reactor designs are much safer and last longer so a long of the concerns of radioactive waste have largely been alleviated.
Quick points: Too expensive with necessary safety measures, Chinese citizens don't want it after Fukushima, renewables are already cheaper, and electrical demand growth has declined unexpectedly.
My opinion: We should still explore fusion technology and spend on R&D, but fission is already dead. Renewables and storage full speed ahead.
Fission will always be there if the alternatives don’t pan out. Its cost is way too high ATM considering the alternatives, but as those alternatives are exhausted, we still have 90,000 years of nuclear fuel to exploit if we need it. The other possibility is that its cost comes down, then it is competing on a more even field with other renewables.
Storage works really well with nuclear, which by itself is very hard to ramp up or down (worse than coal, in contrast to gas and hydro that can work on demand).
Fukushima is bad press and also Fukushima was designed and constructed in 1960s, that's Gen I design and let alone they cut corners in safety. Like I said, Gen IV is much much safer and produce much less radioactive wastes.
Also nuclear fission might not be relevant if humanity cannot survive after 2040, according to IPCC's climate change report (I am doubtful we will even be able to get nuclear fission power plants commercialized by 2050 TBH.)
If fission is dead, then earth is dead. There is no way we'll survive if we continue to burn coal at the rate we do, and renewable don't work at scale yet and storage is not yet solved. Fission is the only thing that can provide us with enough clean energy in the near term (next 50 years).
We have to solve the problem in the next 10-12 years. The median nuclear plant construction is 7.5 years, with the US medians being more in the 18-20 year duration - with the very most recent nuclear projects mostly being shut down mid construction because of cost and schedule overruns.
Even France, with one the most mature and well run nuclear power programs is concluding that the next wave of power investment makes more sense to make in renewables instead of nuclear.
I suspect we will solve our problems with renewables + storage (which are still rapidly declining in cost).
Regarding France, it seems that we have lost the actual knowledge on how to build nuclear power plants. Which should have been expected given that we stopped building those for quite a while, so of course the know-how is gone.
Flamanville, the first EPR in France, was schedule to start running in 2012 for a construction cost of 3.3 billion EUR. It is now expected to start producing electricity in 2020 for a construction cost of 10.9 billion EUR. Emphasis on expected...
If you read past the public/gov't support for Nuclear in the article (the "Declining Options" section, link repeated for convenience), it implies that even China, whose multi-plant build plan should have ensured declining costs and on schedule builds has been experiencing unplanned cost growth and schedule delays.
The economic comparisons are ending up that Renewables and even Renewables+Storage is much lower to even costs, at a much lower risk profile. And if you watch energy company investments in renewable and divestment in nuclear projects - the companies studying the matter in detail seem to be choosing the same direction.
It's not just current costs, it's the rate of change in costs. Renewables and storage are declining in cost rapidly, and any plant built to today will be competing in 10 or 20 years with frightening (for them) cheap competitors, if the trends hold up.
Some of the French issue stems from wide-spread anti-nuclear sentiment. Fukushima galvanized a the anti-nuclear movement. Last month, Macron announced the closure of Fessenheim plant after protests and petitions passed over fears of seismic activity and potential flooding.
The originally proposed construction schedule for Flamanville 3 was 4.5 years. That was a very aggressive schedule. Even reactors completed before Chernobyl, e.g. Cruas 3, took more than 5 years:
Generation III reactors like the EPR and AP1000 were supposed to be simultaneously faster to build and safer due to standardization and careful design. The actual experience of building EPR and AP1000 reactors has torpedoed the "faster" part of that justification. The troubled, prolonged builds have also killed the original lower cost projections.
At this point the the original cost and schedule estimates for EPR and AP1000 projects alike look so optimistic that they were basically fraudulent. These projects were troubled even before Fukushima aroused a new wave of anti-nuclear sentiment among the public.
I still believe the empirical evidence that nuclear power is a very safe way to generate electricity. I also believe the empirical evidence that nuclear reactors are expensive and slow to construct. "Generation IV will be safer and faster to build" -- ok, for a while I believed those same claims about Generation III. The next time I'll believe those claims about a new reactor design is after it has already entered commercial service.
This conclusion from the same French agency has been the result since 2015, with prices of Renewable alternatives making that predicted result more and more solid.
There's a difference between the time it takes to solve a problem, and the time it takes to implement the solution.
How long till we solve renewable production/storage problems? How long to refine those solutions to the point where it takes 7.5 years to deploy the solar equivalent of the Bruce Nuclear Generating Station?
The time between then and now is the amount of years the world will be burning coal.
Here's an integration problem. Lets compare a project to put 100MW of power coming online from renewable vs nuclear spread over 10 years. In the Renewable case we put 10MW online per year every year and start producing power, in the nuclear case, we finish the plant after 10 years and start producing power. How much carbon do we offset in the two scenarios after 10 years?
For bonus points, even if the cost were exactly the same per unit of power, do a cost analysis of which costs more to implement under the different project timelines, using different financing scenarios?
Seems to me the obvious solution is to build wind/solar as fast as we can, while also building nuclear because by the time wind/solar reaches enough market penetration where variability is a problem, the nuclear will be ready.
We should also spend a lot of money working on storage solutions, but with the planet at stake it doesn't seem smart to put all our eggs in that basket.
Grid scale storage solutions are already commercially viable in may areas power provisioning, and have a crossover market in auto battery development. Companies are already bidding projects with renewable+storage mixes at costs already even to lower than nuclear. There is no reason to wait - structuring for nuclear is just a huge financial drag.
Those articles don't have numbers on how much energy they store. So far I haven't seen any that could get through a windless night. Recently I ran the numbers on Tesla's big battery project, and for that much storage it cost significantly more than nuclear.
Costs are going down, but MSRs look a lot cheaper than conventional nuclear too, so if we're going to look to the future let's do it with both.
> Also, newer reactor designs are much safer and last longer so a lot of the concerns of radioactive waste have largely been alleviated.
...in countries that are large enough to make it "disappear".
Meanwhile normal sized countries are still struggling with old waste and new waste. See Germany. Meanwhile reprocessing as it exists is economically pointless, while it reduces the amounts of highly radioactive material enlarges the amounts of mid and low radioactive material and doesn't help with the stuff that has been insufficiently stored already. Also Sellafield and La Hague are probably polluting water.
Transatomic claimed to have the fuel utilization of fast reactors without being a fast reactor. That turned out not to be the case.
However, there are a bunch of other startups working on molten salt reactors, including Bill Gates' Terrapower, Terrestrial Energy, Thorcon, Moltex, Elysium, and Flibe. The farthest along is probably Terrestrial Energy, which has gotten through the hardest part of Canada's licensing process.
It's a niche technology, and doesn't address the main problem of fission (that the reactors are too expensive). At least it serves as a counterargument to those who want to make fusion-fission hybrid reactors.
Also uranium-fueled molten salt reactors, using chloride salt. These will be fast reactors and have pretty much the same advantages as the thorium designs. Terrapower, Moltex, and Elysium are going this route (though Moltex is planning a thorium-fueled version as well).
It's three or four times as abundant as uranium, and about 400 times more abundant than U235. However, with fast reactors you can get power from all the uranium, not just the U235.
Uranium is currently a small portion of the cost of nuclear, so it can't be that hard to mine, especially after we only need 1% as much for the same amount of power.
Either keeps us going for thousands of years, and after that we could extract uranium from seawater until the sun goes out.
If I recall the fusion meme correctly, it is perpetually 10 years from now... Assuming it gets properly funded. Though I also believe that fission research and plants still have their place, especially if you care about carbon emissions.
China's approach to nuclear isn;t just environmentalism. It is largely a national pride project. Fission is an area of science that china knows it can excel in because, frankly, the west isn't doing much. I applaud china's efforts. I think we need fission energy. But I worry national pride isn't reason enough to maintain the program indefinitely. Coal prices are dropping. Will china continue to roll out fission reactors if/when coal falls off the price cliff?
It's much less a pride than a survival instinct. Just think about it, Beijing was under siege of heavy smog for over a decade by now. If Washington D.C. was like that for since Trump became the president, would he still advocate coal?
I suspect we will transition to PV before fusion actually becomes viable. Even if we had a working net-positive-energy-balance fusion plant today, it would be incredibly complicated and expensive to build and maintain. The temperatures and energies involved are simply massive. On the other hand, we already have a giant self-sustaining fusion reaction happening in our sky. We can throw down some solid state and increasingly cheap panels to collect that energy. Regardless, we should continue to invest in fusion, but we should also invest in PV research, especially into ways to decrease cost and complexity of manufacturing solar cells.
Bottleneck to PV is battery capacity. For Solar to meet peak demands and replace fossil fuels there has to be storage capacity and likely a fair bit of investment into grid infrastructure to meet volatile productions. Getting utility companies (a highly regulated monopoly in most cases) to do anything is a slow and painful endeavor.
The more time/location dependent energy sources we add to the grid, the more valuable and necessary on-demand energy to buffer with will be. Same goes for a steady producer like fusion/fission: an increasing value proposition as these renewables are added.
We should definitely be doubling down on PV, but stay aware of other options as it comes with trade offs.
PV just doesn't scale in the same way. There's only so much surface area to cover in panels. The power density of fusion is so many orders of magnitude larger that even with cheap reliable solar panels I think there will always be a use for working fusion
PV scales fine. Do the math, please. There is far more than enough land onto which we can put PV farms. And the cost/W for solar (of which the cost of land is small fraction) is two order of magnitude below current fusion machines.
So hypothetically, if all developed countries suddenly decided that it was worth whatever the cost, could we get to 100% renewable in say.. 10 years? How much of our activity would need to be directed at this? Not even research, if the plan was just make as much renewable energy as we can with current methods as fast as we can.
Of course this would never actually happen and we're in all likelihood gonna continue to trash the place, but is this possible even in theory?
I'm imagining the solitary life of a caretaker living in a little ship that travels the canals between acres of floating cross-linked solar panels, fixing wiring and washing off salt deposits.
Poetically, it would be a tale of isolation out in the middle of the Pacific, but I suppose you'd need to stay close enough to shore that you can transmit the power using wires, unless it's batched up in chemical storage.
If you perform electrolysis of sea water the main products given off would be hydrogen and bleach, both of which could be piped or shipped (if you filled an oil tanker with hydrogen, would it be lighter than air?) back to shore. Although a leak of bleach into the ocean may not be very good, it's probably no worse than the damage done from oil.
Fusion has proliferation problems too. In some ways this is easier than using fusion for energy production. A Q = 0.1 DD burning reactor, for example, would be useless as a power producer, but would produce plenty of neutrons (at lower, less damaging energies) to make plutonium in a subcritical natural uranoium blanket. And it would not need to breed tritium.
It got downvoted because it is not true. PV scales so well that people are voluntarily throwing panels on their roofs to reduce their energy bills. It scales so well that even with current single junction cells, we could cover just 1% of the Sahara with panels and meet the entire world's energy needs. When multi junction gets cheaper, it's basically end game for power generation. And you're probably going to say that storage is a problem, but again storage is something that scales so well people and utilities are buying battery systems all over the place while multiple giga-scale battery factories are coming online in the next 5 years to push prices even lower. Plus High voltage DC power transmission can get power thousands of miles with surprisingly low losses.
And why do you think fusion might be necessary for the following 100 years? Energy use per capita has been dropping in developed countries for years. Fusion really only makes sense as a "must have" technology for space exploration, which current reactor designs are so far away from it's basically a joke.
I wonder if working fusion utility power generation, by the time it is working fusion utility power generation, might end up being more expensive than putting solar in space and beaming the power, given the potential for launch costs to drop and the possibility of even doing the panel manufacturing up there using asteroids as raw materials in the long run, so avoiding the gravity well cost. Economies of scale can get very big in space and if we are comparing to fusion research we should look at the medium to long run.
A lot of people are saying fusion is still decades away. That might very well be true but it might be centuries away unless we change the way we fund the research. Nuclear fission and fusion research are still happening but there's no sense of urgency at this point and it's not a very popular topic with politicians given the issues with reactors invented half a century a go. Back in those days there was a real sense of urgency and no cost were spared to get things done. Kennedy says go to the moon. Ten years later it's done. The fear of the Russians getting there first drove the US to do amazing things.
This stuff doesn't happen by itself and will need a lot of investments and planning to get it done. At this point a reasonable question to ask is whether the US will be the one that makes the breakthrough here. They are not the only ones working on this and arguably it's not a big priority in the US to be working on this at all. What happens when e.g. China gets there first? They are working on this as well and they seem to be getting some results. They are also planning to go to the moon pretty soon. And a lot of the clean energy tech we use comes from them as well.
Just because deuterium is cheap doesn’t mean Fusion energy plants will be anywhere near economically competitive with conventional power sources even most renewables. Many of the presumed benefits such as waste control are not as rosey as most people believe.
It is clear now that plant scaling with known methods are entirely dependent on magnetic field strength. More powerful magnets will mean more hope for tokamaks.
Entirely new designs are probably not what the doctors are ordering because nothing of the sort is anything close to a surefire success in the wings.
So many concepts have come and gone. Tokamak was the closest they ever got. Look at the plant schematics. Its like building a furnace from a humongous collection of delicate swiss watches.
Even with powerful magnets, the power density of a fusion reactor is limited by what the first wall can withstand, and will always suck compared to fission reactors. There's little hope a fusion reactor will be able to compete with fission, never mind the technologies that are beating fission.
What high fields might do is allow use to make small, uncompetitive fusion reactors, instead of large, uncompetitive fusion reactors.
At the risk of inciting a flame war that I might not be able to understand, is there any way to characterize current fusion projects against each other? For example, what can be said about the promise of ITER vs Wendelstein 7-x?
Part of me realizes that there’s no such thing as a “failed” scientific experiment and that diversity of approaches is good. The other part of me thinks that a public and competitive spectacle would also be good.
ITER will be an actual tokamak fusion reactor producing energy. Wendelstein 7-X is a plasma containment experiment based on the stellarator design. There will be no fusion.
Technology for magnetic enclosure was advanced significantly by both. In this regard, they profit from each other.
Tokamak reactors require a pulsed operation mode. There is no way to sustain fusion for longer time.
The Stellarators design allows continuous operation, putting less stress on the structure. The calculation of the winded enclosure structure is quite complex and it has only become possible to design and implement with sufficient precision recently.
If I'd have to "bet" on a design, it would be Stellarator. If you understand German, listen to this podcast. You won't regret it: https://alternativlos.org/36/
People keep saying Wendelstein won't do fusion but that's not the case. Currently the 7-X isn't doing fusion because they're using hydrogen. But they plan to use deuterium later, just like all the other fusion research reactors, and they'll get fusion reactions when they do. There's really no reason not to; you get more data and it's easy. People fuse deuterium in their garages with home-built fusors.
Exactly! AFAICT, the trickiest unknown is maintaining plasma stability and not degrading the insides (and then, breaking even on power while doing so.) Wendelstein seems to be on track to steady-state operation; they've held plasma for 100s, and their graphite shielding seems to be delivering cleaner plasma streams.
The design for the 7-X wasn't feasible until supercomputers got powerful enough. We know how to run those simulations; fusion should get more practical as computers get faster.
Thanks to progress in superconductive magnets, a new reactor type developed by the MIT called SPARC might likely become the first Fusion Reactor to achieve net energy output before 2030, producing 200MW in 1/65th the volume of the ITER design, at a fraction of the costs.
All based on very solid physics with only littly uncertainty remaining. Wow.
I all for research into potentially valuable tech. but we have to consider the fast-falling cost of renewable energy. by the time fusion gets realized at scale, we might not need it anymore.
Fusion (once realized): steady energy regardless of weather conditions, from maybe a few installations per country
Renewables (solar, wind): dependent on weather conditions, would thus require battery farms for backup during wind-still nights or days with overcast etc.
In my mind the ideal future scenario is a compromise between both solutions:
Have fusion always on and provide a base level of energy production sufficient for need plus a few percent. Then have renewables lower the target for energy production through fusion when available. Then we would not need giant battery farms and renewables would get used to the best of their ability/availability while not restricting energy consumption due to them not being available 24/7.
Maybe even leave a select few coal/fission plants available but powered down as a sort of UPS for the energy infrastructure, just in case fusion is N/A and renewables aren't enough to cover the need.
We should be funding the shit out of Fusion and molten salt fission reactors. We're gonna also need to build shitloads of carbon scrubbers and water desalinization plants.
If our goal is basic research, sure, fusion is great.
But if our goal is to achieve carbon neutrality ASAP, we can't count on fusion to help because we don't know when it will start working. On the other hand, renewables + battery leveling are here today and ready for intensive investment.
Yes, let's do both. But I don't believe fusion research will provide a short-term alternative to CO2-emitting power sources. I think it's fine with to spend 1000x on conventional renewables compared to fusion. We can employ an absolute army of technicians and factory workers today to build out renewable generation infrastructure, while fusion gets a steady research budget for post-docs, career physicists, materials engineers, etc.
I have no idea if nuclear fusion is feasible in the near future, or what kind of timeline is required, but I don't see any downside to spending money on projects like this. Pure scientific pursuits seem to be fund able at relatively low prices, with massive upsides and no obvious downsides, other than the opportunity cost of the money being spent.
The downside is that the public will spend 10s of billions only for some billionaire "startup" to hire away the physics expertise and the public ends up paying a monopolistic/oligopolistic premium. Now theres nothing new about that.. but when talking about throwing tons of public money at something it's important to control the terms on which the public money is spent and who absorbs the risks/rewards.
Fusion absolutely will not be feasible in the near future. We don't even have the materials that would be needed to build them. In any other field of engineering, lack of materials is a showstopper, and new material development is always painful and slow. And if you examine any of the designs with a skeptical eye none of them seem promising, and all involve lots of handwaving.
ITER cannot lead to an economically competitive reactor, even if it achieves every one of its stated operational goals. It's a massive dead end waste of money.
My original comment is entirely reasonable. Fusion faces generic obstacles that are likely unsolvable, and certainly unsolvable in the near term.
Consider the problem of tritium breeding. Fusion reactors have to make their own tritium -- T from fission reactors would be far too expensive -- but tritium breeding blankets cannot be tested without a working fusion reactor. And the requirements for the breeding blankets are seriously constraining. They must achieve some neutron multiplication (from (n,2n) reactions of energetic fusion neutrons) to offset losses, not lose too many neutrons to penetrates/parasitic capture, and be able to give up the produced tritium fairly quickly. And there are very strict limits on how much tritium can be lost to permeation into reactor materials (or lost from the reactor exhaust, since ~99% of the injected tritium doesn't fuse).
No one knows how to do this, or if it can be done economically, or even if it can be done at all. And I repeat: testing it is going to require a working fusion reactor! This circular dependency in development will be painful to run around, and won't happen quickly.
Then there's the matter of materials that can withstand prolonged exposure to fusion neutrons. These materials have not been developed, in part because this again requires something close to a working fusion reactor (at least, something with Q at least ~0.1), and much painful rebuilding as that reactor, built with less adequate materials, destroys itself over time. This material development will not be fast, so we will not have working, practicl fusion reactors soon.
Even when all that is solved, the fundamental problem of fusion -- low volumetric power density -- remains. That alone seems insurmountable. When you see a fusion reactor design, ask what this power density is. For ITER, it's 0.05 MW/m^3. For ARC or Lockheed's design, it's around 0.5 MW/m^3. These are very bad compared to fission reactors.
A final point: the complexity of the irradiated part of a fusion reactor (the part that's too radioactive for hands-on maintenance) will be MUCH higher than that of the similar part of a fission reactor. Reliability is going to be an enormous problem. Making fusion reactors reliable enough for them to be practically interesting, even if all other problems were solved, will take much experience and time.
Fusion is a materials science problem and materials informatics (machine learning methods for improving properties and / or devising new alloys) will help immensely once a new generation of digital-native scientists comes into the working force. Fusion might not become economically viable for a long time yet, though, so investments could very probably be moved elsewhere sooner than later. Healthcare for aging populations in the West and a new space race from China come quickly to my mind as powerful “distractions” from ITER part II, in the case part I ignition goes well by 2030. Smaller, more efficient reactors would not solve the energy problem even if they go successfully past the laboratory stage, in that being out of question imho.
Distractions from ITER would be welcome. The power density of ITER is ~0.05 MW/m^3, some 400x worse than the power density of an LWR reactor vessel (and 2000x worse than the power density of the LWR core inside that reactor vessel). It's a project where research money goes to die, and new materials are not going to help that.
Power density is irrelevant for fusion, though: you will never exhaust fusion “fuel” on planet Earth. It will never be an efficiency problem, like it is for fission aka uranium.
No, power density is very important, since it directly affects how expensive fusion reactors will be. The cost of a machine is a function of its complexity and size; fusion reactors will be both much larger and much more complex than fission reactors of the same power output.
Possibly yes but, even the case, the US, the UK, Japan and France would switch to fusion immediately, if feasible, to get rid of fission and its waste. Renewables & nuclear are the perfect mix to contain greenhouse gases emissions, that’s why the debate is so hot.
No, nuclear and renewables do not mix well at all. Intermittent low cost sources of power shoot nuclear's baseload business case in the gut. The reactors cannot sell power at high enough price enough of the time to make sense.
You know, it is renewables to lose, apart of local places blessed by any sort of competitive advantage (water, silicon, etc.). However, I am not here for politics and you simply cannot beat nuclear by numbers, though.
Yes, fission creates waste, but fusion reactors as currently envisioned would also create radioactive waste — not the fusion products themselves — but materials of the containment vessels which have been bombarded with neutrons.
Fusion can’t be done now so construction costs are unknown at this stage. Graphene is the first of many wonders we can expect from materials science this century imho and it is extremely cheap.
In what fantasy scenario does a much larger, much more complex, made from much more advanced materials, system end up CHEAPER than the smaller, simpler, low tech one?
I'm not a super believer in the possibility of fusion, but you can imagine that there might be benefits from doubling the size of a reactor in terms of decreased operational costs or even decreased construction costs (less need to duplicate infrastructure).
But here I'm talking about size for a given power output, not increasing size and power output together. The size/power of a fusion reactor is much larger than the size/power of a fission reactor, for fundamental reasons.
Fusion output would be unlimited (almost), you would then have solved any other problem apart of obsolescence of materials. Any other tech would be finite or more wasteful in comparison.
> A fusion power plant, it estimated, “could use only 5 kilograms [11 pounds] of hydrogen to generate the energy equivalent of 18,750 tons of coal, 56,000 barrels of oil or 755 acres of solar panels.”
Translation: The coal industry, the oil industry, and the solar industry do __not__ benefit from fusion. Using history as a reference, it's fairly safe to presume they will use their influence to sway any decisions in their best interest.
I get that fusion can theoretically transform vast quantities of stuff into useful energy. Can anyone comment on how scalable it would be if proven viable? Can it be built on a large scale profitably? Can it be built to serve remote locations off major grids? Can we ship it in reasonably sized space ships and use it to build bases elsewhere? Can we write off low energy costs to just churn on some sort of climate saving terraformer?
Fusion scales incredibly well. For a given working reactor design, efficiency increases with size. I think viable working fusion would lead to a more interconnected grid because of this as opposed to smallscale fusion reactors being deployed in semi-remote areas. On the other hand truly difficult to reach places would be perfect for fusion as once it's built it takes very little fuel to run.
Fusion reactor economics get worse as you make them bigger (assuming the smaller one works at all). That's because their power output is limited by what the first wall can withstand. By the square/cube law, their power/volume must decline as they are made larger.
>Can it be built to serve remote locations off major grids?
No, fusion reactors are required to be a certain (very large) scale before they can provide a net output of energy. You can find kits online to build an actual fusion reactor in your garage, but it will consume more energy than it produces.
Is terrestrial fusion even desirable, I understand it will not use the same "clean" reaction as stellar fusion (deuterium-tritium or D-D vs ordinary hydrogen).
Stellar fusion isn't really clean in the way you imagine; there are lots of reactions in the star core that produce free neutrons, they just get reabsorbed by something else because they can't realistically exit the system like they can in a tiny reactor.
Nor is it realistically achievable, anyway. Fusing products out of bare protons just isn't productive enough at achievable temperatures.
In a star like the Sun there are very few free neutrons produced. There are non-exploding stars that produce some neutrons, but they are AGB stars where the core gets hot enough for (alpha,n) reactions to occur.
Hm... maybe I'm misremembering, but I swear I saw an analysis that showed neutron loss from a small (i.e. reactor scale) blob of solar core plasma would be comparable to what you get from existing power reactions. It's true that almost all the energy production in the sun happens from reactions that don' t involve neutrons, but the neutrons are flying around nonetheless (and, in a reactor, would fly right out of the containment).
Something endothermic? Are you really asserting that no such reaction exists? They clearly do, the question is whether the cross sections are high enough. The list of reactions you find in typical explainers are just the ones involved in energy production.
And I'm no expert, so I'm not going to be able hand you the evidence here. But like I said I swear I've read this analysis somewhere, and something about your tone tells me maybe you are misunderstanding the point.
The most likely would be 13C(alpha,n)16O, but the rate of this would be very low at the temperature of the solar core.
You might also point to (alpha,n) reactions on Li, Be, or B. But these should be slower than (p,alpha) reactions on these elements, which destroy them at temperatures well below (by a factor of ~3 or more) that of the center of the sun.
Let's see how far I can push your argument. There will be some 7Li produced by a side branch of the PP cycle (although it is quickly destroyed). Also, 4He produced by the various fusion reactions will initially have energies in the MeV range (~1000 mean thermal energy in the core), so it's possible (alpha,n) reactions could occur from them as they slow down.
Lets be honest about fusion - Experts urge the US to continue employing them for another 20 years. And thats coming from someone with a physics background. The fusion industry (and thats what it really is) has managed to string the public and policy makers along for 60 years so I guess why stop trying now. Fusion will never be cheap and won't be clean either.
While I agree that there is too little money in Fusion research, I would recommend building Thorium reactors. Thorium reactors could be in a production setting, if financed, in less then 5 years.
Trump and the Republican congress doubled fusion funding in the May omnibus bill, literally saving ITER from having to delay again. Republicans have always been solidly for nuclear power and its derivatives because the only companies with the capital and guaranteed future cashflows to build nuclear fission or fusion plants are the existing energy companies, who have traditionally aligned with Republicans.
A well-built modern fission plant is far safer and more environmentally-friendly than almost all the other solutions out there save for solar/wind/geothermal.
Fusion is the holy grail, though, and with good reason. At least with fusion (as with flight 100+ years ago), we have only to look up during the day to know it's feasible because it's being demonstrated, live, every day!
The sun's fusion is powered by the gravitational attraction of ~10e30 Kg of matter. That is not even remotely an option on Earth, so there is no evidence of feasibility about the energy produced by the sun, aside from the fact that it demonstrates that fusion as a concept makes sense.
Does it tho? Star fusion produces the exact amount of pressure needed to counter the gravitational attraction which is why they don’t collapse or blow up while the fusion reaction is stable, when it’s not the result isn’t pretty.
So in essence stars aren’t energy possitvie (or if so only slightly relative to the energy of the reaction) they just convert one type of energy into another.
This argument makes no sense at all. "Pressure" and "power" don't even have the same units. They are entirely different things.
Let's try to rephrase things in a way that makes physical sense.
There is energy embodied in the Sun. This is the kinetic energy of the electrons and ions that make it up, the energy of the thermal radiation mixed with this plasma, and the (negative) gravitational potential energy.
As the sun formed, energy was liberated by gravitational collapse. This heated up the Sun's material and got things going.
We know (by the wonderful Virial Theorem) that the negative gravitational binding energy of the Sun is ~2 times the internal energy of its particles and radiation.
We can then ask: how does this energy compare to the rate that the Sun is radiating energy? This ratio would give a timescale over which the Sun would cool off, if there was no energy input.
This ratio is on the order of ten million years. But the sun is hundreds of times older than this. So, we can conclude the energy yield of the sun, the ratio of fusion energy output to the initial gravitation energy input that heated it up, is pretty darned good, on the order of hundreds.
The pressure caused by the sun’s ongoing fusion reaction is directly opposite to the force of gravity which constantly wants to contract it, these are exactly equal and opposite this isn’t an argument this is the basis for how stellar fusion works.
∆P · A = −GM(r)m This is the formula.
The sun isn’t powered by the initial gravitational force that heated it up but by the continuous gravitational attraction it experiences all the time.
A star is constantly in the balance between the forces of gravity and the outbound pressure from the fusion reaction this balance is what keeps it going.
So unless you somehow found a way to turn off gravity the sun and every other star in the universe experiences a constant “input” of energy due to gravity.
So the only thing that doesn’t makes sense here is your attempt at physics, hydrostatic equilibrium is what keeps stars going and it’s between the pressure of fusion (or degenerate pressure once fusion stops) and gravity.
> So unless you somehow found a way to turn off gravity the sun and every other star in the universe experiences a constant “input” of energy due to gravity.
The word you want here is "catalyst", not "input". The gravitational pressure has to be there, but it is not consumed.
"The sun isn’t powered by the initial gravitational force that heated it up but by the continuous gravitational attraction it experiences all the time."
This is nonsensical bullshit. Pressure in a static situation does not work, and produces no power.
Maybe you should take a course in freshman physics?
The fusion reaction of a main sequence star is a balancing act between the outward pressure of the fusion reaction (radiation and gas pressure primarily) and the inward force of gravity.
Like this isn't a conjecture we have a very good understanding of how stars work, stars achieve a hydrostatic equilibrium, if they wouldn't they would either explode, collapse or oscillate, the reason why the fusion reaction doesn't cool down is because gravity is constantly pushes the material inwards if it wouldn't the star would expand until the fusion reaction stops and would cool down.
The constant force of gravity is what constantly keeps the a star in a condition where fusion can happen, basically gravity is what is used to overcome the nuclear forces allowing protons to fuse.
"Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity.[1] Gravitational collapse is a fundamental mechanism for structure formation in the universe. Over time an initial, relatively smooth distribution of matter will collapse to form pockets of higher density, typically creating a hierarchy of condensed structures such as clusters of galaxies, stellar groups, stars and planets.
A star is born through the gradual gravitational collapse of a cloud of interstellar matter. The compression caused by the collapse raises the temperature until thermonuclear fusion occurs at the center of the star, at which point the collapse gradually comes to a halt as the outward thermal pressure balances the gravitational forces. The star then exists in a state of dynamic equilibrium. Once all its energy sources are exhausted, a star will again collapse until it reaches a new equilibrium state."
Now in fusion experiments we supplement gravity with magnetic fields and pressure from high temperature plasma, but the same thing stands we need to apply constant pressure to allow for protons to fuse into neutrons in order to have hydrogen > helium fusion, not only that but we need to apply even more pressure when the reaction actually happens to keep it because now you have radiation pressure that wants to expand your plasma which would stop all fusion unless countered.
This is exactly why I asked if we have any models which are actually energy positive.
>Maybe you should take a course in freshman physics?
The only way the sun could be powered by gravity would be if it were gradually collapsing. If the radius of the Sun is constant, no gravitational energy would be released. In this situation the pressure in the Sun is not a source of power, any more than the pressure in the tires of your car could be a source of power.
This was actually the theory of how the Sun was powered, a century ago. This caused problems, since the maximum age of the Sun under this scenario is just tens of millions of years, and the Earth was clearly older than that.
We now know the Earth is 4.55 billion years old. The Sun cannot be powered by gravitational collapse, or it would have stopped shining long ago. The pressure and temperature of the core of the Sun set up the conditions in which fusion can occur, but they are not the source of energy that is powering the Sun.
Again do you understand what dynamic equilibrium is? We have awarded a Nobel prize for this, a star is powered by fusion which is maintained by gravitational collapse it collapses to the point where it achieved a hydrostatic equilibrium between the force of gravity and the outward pressure of the fusion reaction that wants to blow it up.
If the fusion reaction overcomes gravity it expands until fusion stops, if gravity overcomes fusion it collapses again until another equilibrium is reached by either fusing heavier elements or through degeneracy pressure, if that cannot be stopped then we get a black hole.
>The Sun cannot be powered by gravitational collapse, or it would have stopped shining long ago.
The Sun isn't powered by gravitational collapse, it's fusion reaction is maintained by it, just like we must maintain a fusion reaction by having the right pressure to allow for proton fusion in the first place and countering the radiation pressure from the fusion reaction which is why we need to constantly supply the reaction with energy to maintain it.
The fact that you still do not accept this is simply mind boggling, consider reading up on hydrostatic equilibrium and stellar nucleogenesis.
"An interstellar cloud of gas will remain in hydrostatic equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the virial theorem, which states that, to maintain equilibrium, the gravitational potential energy must equal twice the internal thermal energy."
Ironically enough this is exactly with what you've tried to counter my initial post, gravity doesn't go away it is what is keeping the reaction going, if you turn off gravity the gas would cool down due to the expansion and all fusion reaction would stop, but as long as gravity is there the reaction will continue until there is no more fuel to fuse.
"So in essence stars aren’t energy possitvie (or if so only slightly relative to the energy of the reaction) they just convert one type of energy into another."
which is utter crap, at least in the case of a star like the Sun, as I demonstrated several messages back. They are massively energy positive. The fusion energy output is orders of magnitude higher than the gravitational energy that was liberated as the Sun formed.
What confines the fusion reaction and prevents the star to blow out due to the outward pressure from the gas pressure and the radiation pressure powered by the fusion reaction? Basically why isn't a star a giant thermonuclear bomb? This is gravity, yes no energy is technically extracted, but you can no more have fusion in stars without the constant pull of gravity which confines the fusion reaction in the same manner as magnetic confinement fields achieve the same effect on earth.
This feels like hydrogen fuel cell tech — “something better on the horizon” that will keep you from investing in the obvious: free energy from the fusion reactor that already works in the sky. I would put every dollar of public fusion research money into solar and battery storage. That works now. The only thing fusion research accomplishes, like HFC, is prolong dependence on carbon energy.
There is no naturally occurring source of hydrogen. That’s why you see ads for HFC from Shell and Chevron. Hydrogen must be made from oil or gas. Salt water electrolysis doesn’t really work at scale as it requires even more oil and gas. Even if you do SWE with renewable energy, it’s about 22x less efficient than putting the electricity in a battery. We have fusion. It’s in the sky. We don’t need it on earth.
Gravity storage has its uses but won’t work in urban areas. We are gonna buy cars for a long time, and we might as well also use those cars as a distributed power plant when they aren’t being driven. Tesla isn’t a car company. It’s a power company.
I don't think we have a choice. Human activities are currently completely dependent upon the availability of energy. Right now most of that energy comes from non-renewable sources and is limited. Our only other choice besides nuclear technologies is covering large portions of our planet's surface with solar panels, which in itself might cause problems because they will shade out plants and change weather and climate patterns as they scale. Traditional nuclear plants get us quite aways farther, but have their own risks, and still require absolutely enormous mining fields which isn't ideal. Fusion power however is the holy grail of energy production. We can go pretty much anywhere and find plentiful sources for fuel.
Of course this is assuming small fusion reactors will ever actually work, but we have yet to find a hard limit or insurmountable barriers. We have been progressing slowly but consistently but the payoff would be world changing, potentially even galaxy changing int he longer run.
covering large portions of our planet's surface with solar panels
Have you calculated it? If I recall correctly, it's actually not a large portion at all. It's large in the sense that it would be a large infrastructure project, but it's not larger than the combined area already covered by buildings.
That is assuming we keep similar power usages as today, but many of our largest industries are consuming unaccounted for fossil fuel energy. Fertilizer for example, fossil fuels are used as a reagent in creating artificial fertilizer, on top of already huge energy costs. The energy required to make fertilizer out of the air and water, rather than fossil fuels, is 100x more at best case. 60% of our total crop yield is the result of artificial fertilizer. Then look at plastics, how much more energy is required to create nonfossil fuel hydrocarbon precursors? You can make hydrocarbons from trees, but it might take an entire tree just to make a few cheap plastic containers.
Many other industries are also powered by mined and drilled organic fuels and minerals, but are still fairly limited in availability, at least for such cheap prices/energy requirements anyways which will rise into the future.
Building solar panels to power our planet today isn't insurmountable, but what about 20 years from now? 50? 100? Power costs are the limiting factor in many industrial processes, including farming, steel and aluminum production, aviation and rocketry, indoor farms, plastics, and nearly every other form of material synthesis.
Don't get me wrong, im not advocating against solar power in anyway, however I don't think it is an effective source for powering our largest industrial processes into the future. Even a small 10 man ceramics shop can draw enough power that they need to call up the local power companies before they turn their large furnaces on, I see no reasonable way of storing and supplying those kind of immense power requirements with solar panels and current storage technologies in any economical way.
Do we even had a model for Fussion that is energy poasitive? The only Fusion reactors we know to work, work by converting gravitational potential energy into light/heat through fusion this is how stars operate.
All fusion reactions so far require an external input of energy not only to start them but often to sustain them and even those which are self sustaining for a short period of time grind to a halt once you try to extract energy from the system.
So in all honesty while I’m not by any stretch of the imagination an expert in fusion physics I can at least understand conservation laws, does any of the current experiments even relies on a model that is at least proven in principle to be energy positive?
Stars simply do not "work by converting gravitational potential energy into light/heat through fusion." The "light/heat," or energy, that stars produce comes from the mass defect of the fused atoms. Basically, the binding energy of He is less than the binding energy of the (net) 4 H atoms that go into the reaction. It works so well in the sun because of the long confinement times and the long transit time for energy to get from the center of the the star to the exterior.
"...while I’m not by any stretch of the imagination an expert in fusion physics...I can at least understand conservation laws..."
I don't think that you have a firm a grasp on their application as you seem to suspect, though I agree you don't understand the physics of fusion. Your reasoning is analogous to neglecting the contribution of smokeless powder to the performance of a rifle, because a rifle is just "converting" the energy stored in the hammer spring into energy in the bullet.
Again gravity is what maintains the reaction going, without it the gas would expand and the reaction would stop.
I understand how fusion works, what you neglect is that gravity is what allows you to counter the nuclear forces to cause protons to fuse in the first place, and what keeps the entire thing from blowing out.
Hence stars are in constant balance between gravitational collapse and their outward pressure caused by fusion.
“An interstellar cloud of gas will remain in hydrostatic equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the virial theorem, which states that, to maintain equilibrium, the gravitational potential energy must equal twice the internal thermal energy.”
On earth we exchange gravitational potential with electromagnetism but we still need to apply the same force to counter the nuclear forces and the pressure from the reaction once it starts.
All I want to know is if we have a proven net positive model for this reaction because so far I haven’t been able to find one.
Because as far as I know the vital theroem stands so it doesn’t matter if it’s gravitational potential or any other force it still needs to be twice the thermal energy of the reaction.
But you can continue to downvote without actually addressing anything while ingoring everything we know about stellar fusion and the fact that is triggered and constantly maintained by gravitational collapse.
So no I don’t ignore the role of gunpowder in a gun, you ignore the energy needed to create the gunpowder and cartridge in the first place.
"...the fact that is triggered and constantly maintained by gravitational collapse."
What you have written is not a fact. Forces only do work when they act through a distance. Gravitational potential energy only comes into play during the ignition of a star. After equilibrium is reached, to the extent that the star's diameter is "static" potential energy calculations no longer come into play. No "potential energy" is being "converted" into fusion energy. It's just not a thing.
"...stars are in constant balance between gravitational collapse and their outward pressure caused by fusion."
Because of this balance, no work is being done by gravity. That is, no energy is being released by the force of gravity moving a mass through a distance.
"All I want to know is if we have a proven net positive model for this reaction because so far I haven’t been able to find one."
It's literally E = mc^2, but it's not "net positive." It's net zero. Matter is converted into energy. That's it.
"So no I don’t ignore the role of gunpowder in a gun,..."
It's an analogy, and it's straightforward enough that the onus is on you to work out the pieces a little better than you have. HINT: The "energy needed to create the gunpowder..." is the binding energy in the various nuclei.
>Because of this balance, no work is being done by gravity. That is, no energy is being released by the force of gravity moving a mass through a distance.
I didn’t say it extracts energy from gravity, gravity is constant and it is what keeps the reaction going.
This balance is dynamic equilibrium, gravity continues to counter the gas and radiation pressure of the star’s fusion reaction if you remove gravity from the equation fusion stops because the pressure would cause it to expand until the reaction stops.
If the reaction slows down then the collapse continues until fusion of heavier elements can happen, degenerate pressure can counter it or if neither of those happen you get a black hole.
>It's literally E = mc^2, but it's not "net positive." It's net zero. Matter is converted into energy. That's it.
I didn’t ask you how much energy any given unit of mass has, I asked you for a net positive model for a fusion reaction.
We need to invest energy to make fusion happen then we need to invest more energy to keep the reaction going.
So again I understand where the “excess” energy comes form when two protons fuse into a neutron, however proton fusion isn’t spontaneous and it requires you to expand energy to bring them close enough so they could fuse.
Now in say hydrogen plasma you need to overcome a lot of forces to do that, and more so when the reaction starts since the energy release wants to expand the plasma outwards what I want is to see a net positive model for this reaction.
Might as well ask where the energy comes from the burn wood - each oxidation has an activation energy which must be paid before the heat from burning is released.
However, as long as the released energy is greater than the activation energy (the reaction is net exothermic), some of the excess energy from each reaction (through heat) goes into powering future reactions. Which is why physicists talk about "ignition" - there's a very strong analogy to igniting a fire with an initial spark of energy.
> So far I only hear crickets.
So far I see lots of people spending a lot of time explaining high school physics to you. Do at least try to be polite while this is going on.
Again you seem miss understand I’m not saying that the Sun extracts energy from gravitational potential but you cannot have stellar fusion without gravity it’s not part of some initial condition that is then irrelevant it’s a constant factor.
A good analogy would be walking it’s very easy to do so on earth under constant gravity but it doesn’t mean that you extract energy form gravitational potential which is when you stand on the surface of the earth is for all intents and purposes zero.
However if you switch gravity off you wouldn’t be able to walk.
If we want to simulate gravity in say space there will be an expense to that in terms of say rotating a drum which means we need to expand some energy to do so.
Now with fusion it’s exactly the same we need to bring in the elements into a condition in which fusion can happen and we need to sustain the reaction by not allowing it to expand and cool.
This requires energy so instead of trying to explain me high school physics you might want to answer my original question do we have a model which allows for the extraction of energy form a fusion reaction that does not cool it down until it stops.
And does this model including the confinement energy is energy positive or not.
I didn’t asked where the energy released form the fusion comes form it’s a stupid question all energy in the universe came form a single source that is the Big Bang there is no more or less of it in the universe today than there was 15 billion years ago.
> Do we even had a model for Fussion that is energy poasitive? The only Fusion reactors we know to work, work by converting gravitational potential energy into light/heat through fusion this is how stars operate.
> All fusion reactions so far require an external input of energy not only to start them but often to sustain them and even those which are self sustaining for a short period of time grind to a halt once you try to extract energy from the system.
That was your original question. It contains, as everyone is aware, your original statement that stars work by converting gravitational potential energy into light and/or heat through fusion. This claim is patently incorrect. It is false. It is misleading. It is a red herring, and a canard. You seem susceptible to it, for some reason. My only advice is to just set it down, over there, and don't play with it. The only winning move is not to play.
> And does this model including the confinement energy is energy positive or not.
Sigh. There is no "confinement energy." This is a physics-sounding phrase that you seem to have coined. Set "confinement energy" down over there next to your original question. It's poison.
> This requires energy so instead of trying to explain me high school physics...
Sigh, again. How much energy, quantified, in the mathematical language of physics and engineering? How much in comparison to the energy released quantified, in the mathematical language of physics and engineering? While these are technical questions, the answer, given by physicists and fusion researchers since well before ITER, is: "We get way more energy out. Full stop. Solved problem. Tokamaks work, with a lower size limited by magnet technology, but not by first law physics. (Implicitly, people who question this at length are cranks.)"
You simply have no basis to go around demanding "a model." If it hit you in the face, you wouldn't recognize it. You, personally, can't quantify this "require[d] energy." You, personally, therefore have no reason, other than obstinance, to think you have some relation between the amount of energy released from a fusion reaction and the energy necessary to create the conditions for fusion. None. No other reason. Pure mulishness. The question is dumb. You are dumber for having asked it, and I am dumber for having read it. It is contagiously, toxically dumb. Please stop. There is no longer any nice way to say any of this to you.
And the one thing you need more of is high school physics, not less.
> ...do we have a model which allows for the extraction of energy form [sic] a fusion reaction that does not cool it down until it stops[?]
Which fusion reaction? Where? So, you can set a solar panel up to do "extraction of energy" from the Sun. Experimentally, this has not shut down fusion in the Sun. So, yes? We have a model? Further, there's no way to not "extract energy" from a fusion reaction, whether or not that "extraction" shuts it down. You, and I, generally exist at a lower temperature than fusion reactions. Ergo, we are extracting energy via radiation from every fusion reaction in the Universe, via heat transfer.
> If we want to simulate gravity in say space there will be an expense to that in terms of say rotating a drum which means we need to expand some energy to do so.
There's a legitimately beautiful and elegant answer to all this energy nonsense in that thought experiment. The answer leads to even more beautiful math about energy, momentum, ground states, and stability. It would be wasted, here.
I'm going to go have a shower, and maybe a drink. This has been an awful waste of time.
>That was your original question. It contains, as everyone is aware, your original statement that stars work by converting gravitational potential energy into light and/or heat through fusion. This claim is patently incorrect. It is false. It is misleading. It is a red herring, and a canard. You seem susceptible to it, for some reason. My only advice is to just set it down, over there, and don't play with it. The only winning move is not to play.
That was a gross simplification but technically correct, without the constant force of gravity which confines the gas there is no sustainable fusion reaction in stars.
On earth we replace gravity with magnetic confinement.
>Sigh. There is no "confinement energy." This is a physics-sounding phrase that you seem to have coined. Set "confinement energy" down over there next to your original question. It's poison.
If I phrase it as the energy required to maintain the magnetic confinement field in a fusion reactor in order to maintain the fusion reaction would it be better? Because now you are arguing semantics.
>Which fusion reaction? Where? So, you can set a solar panel up to do "extraction of energy" from the Sun. Experimentally, this has not shut down fusion in the Sun. So, yes? We have a model? Further, there's no way to not "extract energy" from a fusion reaction, whether or not that "extraction" shuts it down. You, and I, generally exist at a lower temperature than fusion reactions. Ergo, we are extracting energy via radiation from every fusion reaction in the Universe, via heat transfer.
Which is exactly my point the, what confines the nuclear reaction in the sun is a complex process which involves the inward pull of gravity this is what prevents the sun from blowing out until it cools down, you constantly keep ignoring this fact.
On earth we use magnetic fields those magnetic fields require power now I agree that in a reaction that is an equilibrium there is no work between the field and the plasma as both of them are opposing and equal but we still need to power that field if we power it by the excess heat from the fusion reaction the question is then is there any other excess heat that can be used to generate electricity in addition to what is required to power the magnetic field, and this is with a hypothetical 100% efficient model.
No energy is being continuously invested by gravity. It is not "keeping the reaction going" in that sense. It's simply freshman physics that tells us that forces only do work when they act through a distance. Because the star's surface is not moving inward, it is not doing work, i.e., giving energy, to the star. Furthermore, the Sun, for example, is probably slowly expanding right now. It will start to do so in time, at any rate. That is, the work done by gravity on the Sun will be negative during that time, and fusion will continue. You just aren't making any sense. You are either not trained in physics, or have failed to understand what you have learned. You could begin to piece together a better education in it by simply following up on my replies in this thread. Please, take it from me, you do not know what you are talking about, and your concerns are therefore not valid. I thought I could help, but you seem to be a tough case.
In short: Forces only do work by acting through a distance. Work is energy. If no work is being done, no energy is being produced. Therefore, gravity is not "energizing" the reaction, because the net motion of the star towards its center is zero when it is in equilibrium.
In shorter: No motion => no work. No work => no energy. No energy => no problem.
Again I understand that work (kinetic) is distance over time.
This ain’t what I’m talking about.
The Sun no more extracts energy form gravity to burn than you extract it when you walk but if you turn off gravity then you can’t do either.
The Sun and every other star aren’t static they are in constant balance between their outward pressure and the inner force of gravity, gravity doesn’t just stop when the ignition point is achieved, this is what confines the star and allows the fusion reaction to continue.
Stars have cycles of expansion and contraction and these are understood they are also entirelry governed by the ratio between gravity and their internal pressure fueled by the fusion reaction.
So if the Sun expands it means it is generating more energy than what the current gravitational force confines it in, it would expand until a new balance is reached it cannot expand forever unless you turn off gravity and if it would it would very quickly stop fusing elements because it would expand until it cools beyond the temperature which allows for fusion.
To the trolls downvoting all the questions here stellar fusion works because of hydrostatic equilibrium which is maintained between gravity and the outbound pressure of the fusion reaction of a star.
That was bad luck with the downvoting, I have heard the gravitational narrative of stellar evolution and element creation before, perhaps in a Feynman lecture? I recall the idea that a cloud of hydrogen atoms has more gravitational potential than the equivalent cloud of heavier elements, basically because the matter is more evenly dispersed. It seems to make a certain sense. Particles get very fast when they close distance, if they can then stick together their kinetic energy has to become something. Interesting to calculate the gravitational energy involved in a neutron and proton getting close enough to be held by each others nuclear forces, beginning from an average separation of say a few microns? I know they have to get through repulsive nuclear forces in order to stick, I don't know if the reaction always liberates kinetic energy. Maybe it depends on what element results.
An interesting topic of stellar fusion should be supernova reaction/s. The creation of heavier elements there can clearly release enough kinetic energy to explode the condensed body. Does that energy owe to the distance that has been closed by particles forming heavier elements, or to loss of mass in the nuclear reactions?
I wonder about the gravitational energy of a cloud of billard balls rather than atoms. If another cloud has the same volume but half the number of larger balls that are twice as heavy. I guess if the two clouds have the same size, weight and density, they have the same gravitational potential - if they start cold, they will both implode with the same force at the center. But this seems to contradict the narrative that conversion of hydrogen to helium should consume or liberate that potential energy.
Nuclear power is vital part of the energy infrastructure to curb worsening environment due to climate change - it's still considered superior than all the other green alternative energies in terms of either 24/7 availability (vs. solar/wind) or massive scale (vs. geothermal) or location restricted (vs. hydro) or carbon-free (vs. biomass/bio-fuel). China realized that in their dire request to transition out their entire energy reliance on carbon-based energies, it's impossible to do without nuclear. Also, newer reactor designs are much safer and last longer so a lot of the concerns of radioactive waste have largely been alleviated.
[1]: https://news.ycombinator.com/item?id=10229697 (2015)
[2]: https://news.ycombinator.com/item?id=17813614 (2018)