Great. The fusion hype is bad enough already. Now its resurgence is going to interrupt the series of posts I’m in the middle of publishing in order for this post to be “timely.”
The first (and much bigger) round of breathless excitement came in December 2022 when the National Ignition Facility (NIF) at the Lawrence Livermore National Lab (LLNL) announced a (legitimate) breakthrough in achieving fusion: more energy came out of the target than laser energy injected.
At the time, I brushed it off without even reading any articles because I already knew about the NIF’s purpose and limitations, and a few headlines told me everything I needed to know. Who cares how much laser energy went in: how much energy went into creating the laser energy? The laser I used for lunar ranging took 5 kW from the wall plug and delivered 2 W of laser power for a dismal 0.04% efficiency. Such is the cost for shaping ultra-brief pulses: lots of energy is thrown away. The headlines were clearly overblown.
Enough students in my energy class in Spring 2023 asked about the fusion breakthrough (doesn’t that mean we’re done?) that I dug into the details. Even so, I still deemed it unworthy of writing up as a post. But a few days ago, my friend asked me if I was excited about the recent fusion news. I hadn’t heard a peep, but after searching I found a new round of articles based on a second “net gain” laser shot and realized I probably ought to put out a quantitative post on the matter, reminiscent of my blogging origins.
In the end, the NIF fusion accomplishment might be called a stunt. Stunts explore what we can do (often after an insane amount of preparation, practice, and failure), rather than what’s practical. Stunts hide the pains and present an appearance of ease and grace, but it’s a show.
Quantitatively, it’s as if you spot a slot machine in a casino that looks very promising. You’re dying to play, because it just feels right—mysteriously appealing to your sense of self. It calls to you. You notice that it takes $2 tokens, but you have none. You go to the window to purchase a token, and are shocked to learn that one $2 token costs $400. Not wanting to look like an uninformed fool, you gulp and buy the token. This slot machine had better live up to its promise! You pull the lever, and surprise! You actually do win! You put in a $2 token and the machine makes very happy noises and flashes lots of lights as it spits out…$3 (and some neutrons, oddly). Queue the headlines! Want to play again? Actually, this wasn’t your first shot: just the first success after years of trying (but hush!).
Energetics
That’s the essence of the story. The December announcement indicated that they launched 2.05 MJ of laser energy onto the target sphere, and 3.15 MJ came out. The recent articles indicate a second “score,” but fail to give energy specifics, other than “more” energy out. I am assuming an incremental bump, still under 4 MJ—otherwise the factor of improvement would be prominently touted in the coverage.
Let’s pause to say: well done! Honestly. No sarcasm. What they did was ridiculously hard, and it finally worked after more than a decade of trying. They actually produced a significant number of fusion events! There’s no faking that, and I’d like to see you try. So let’s be clear that I’m not knocking the accomplishment in itself. My major beef is how we interpret the implications for society. To be fair, the scientists did not supply the hype. They didn’t have to: the rest of the universe was more than ready to fill in that yawning gap.
As I scanned articles from December 2022, most were about the triumph, a reminder that the sun works by fusion, and talk about being the first major step toward limitless clean energy. That’s what people want to hear. It plays right into our cultural mythology: humans defy all limits through ingenuity and technology. Build a story around that theme, and you’ve got yourself some guaranteed click-bait.
A very few articles mentioned the energetic price of generating the laser pulse. In particular, I found one in The Atlantic by Charles Seife:
The “more energy out than laser energy in” equation masks several fundamental problems. NIF’s doped glass lasers have an efficiency of about 0.5 percent, meaning that they would have sucked in roughly 400 megajoules of energy from the grid in order to produce the 2.1 megajoules of light energy…
The second was a Big Think article by Tom Hartsfield.
The laser energy delivered to the target was 2.05 MJ, and the fusion output was likely about 3.15 MJ. According to multiple sources on NIF’s website, the input energy to the laser system is somewhere between 384 and 400 MJ.
And that’s just the laser energetics. The whole facility consumes scads more for countless other purposes. According to the LLNL NIF FAQs (are you letting me get away with a triple acronym?),
NIF’s 192 powerful laser beams, housed in a 10-story building the size of 3 football fields, can deliver more than 2 million joules of ultraviolet laser energy in billionth-of-a-second pulses onto a target about the size of a pencil eraser.
The emphasis is mine, to highlight the point that this is a massive laser and facility. It’s like ten Walmart superstores stacked on top of each other. The lighting alone is likely taking tens of kilowatts, which could hypothetically be run for less than a minute on the energy gain from the fusion pop. It would be fun to count all the megajoules that went into press coverage of the event!
Power Plant Energetics
Let’s connect the 3 MJ output to that of actual power plants, forgetting for a moment the tremendous energy loss represented in getting 3 MJ out from a 400 MJ input. A typical electrical power plant (nuclear, coal, etc.) delivers about 1 GW of electrical power. But it’s a heat engine operating at 30–40% thermodynamic efficiency. So it takes roughly 3 GW of thermal energy to export 1 GW as electricity. 3 GW is 3 GJ per second, or 3,000 MJ per second.
The same efficiency factor would apply to a putative fusion plant. The concept behind fusion power is that it’s just another thermal source—an excruciatingly elaborate way to boil water to make steam to drive a turbine to run a generator. So our 3 MJ would need to be replicated 1,000 times per second to amount to 3 GW.
Laser repetition rates can be all over the map. 1,000 Hz is not in itself unusually fast by any stretch. What is the repetition rate of the NIF laser? Handily, LLNL provides these statistics. The average since 2015 is 377 shots per year, with a high of 417 and a low of 327. That’s about a shot per day—or two on a good day. It’s only 100 million times shy of 1 kHz. Oh dear.
Economics
An interview of physicist Bob Rosner in the Bulletin of Atomic Scientists helpfully puts the NIF in context (it’s not about societal energy). In it, he reinforces some of what we’ve covered, and adds some financial detail.
This facility can do one shot a day; this is at slightly more than two megajoules (of output). For an energy source, it would have to do the same thing at least 10 times a second. If you ask, “Do the lasers exist that can do this?” Not in your dream. The pellet cost a bit over $100,000 to manufacture.
The 10 shots per second, I gather, is if the fusion yield could be improved by a couple orders of magnitude—approaching actual break-even. At $100,000 per (literal) pop, and even just ten shots per second, we’re talking a cool million dollars per second!
Let’s wave a magic wand for a minute and say that the 400 MJ input produced a 700 MJ output for a net of 300 MJ: 100 times the recent breakthrough. This accords with the ten shots per second mentioned above. What is the price of the delivered electricity? After thermodynamic inefficiency is accounted, we get 100 MJ out for $100,000 cost, or $1,000 per megajoule. We are accustomed to using the kilowatt-hour (kWh) as a measure of delivered energy, which is 3.6 MJ. The cost becomes, then, $3,600 per kWh. Typical electricity costs are in the neighborhood of $0.15–0.20 per kWh, so we’re dealing with a cost that is 20,000 times higher than nominal. And don’t forget, we used a magic wand to even get there. It’s closer to 2 million times more expensive currently, and as a net energy loser to boot.
Granted, the research and development phase is not characteristic of operational costs. But try knocking on a venture capitalist’s door and making the argument that you can trim costs to 0.005% of their current amount. Slam!
This massive reduction, incidentally, translates to a cost of $5 per pellet. I don’t care what mass-production slave labor you might dream of employing. A cryogenic hydrogen-ice target made to demanding precision specifications, containing deuterium and transmuted lithium (to make tritium) is not going to cost $5. You lost me at cryogenic. Also, they would have made many pellets by now and I’m sure don’t relish spending $100,000 each. If they’re clever enough to accomplish fusion, they would be clever enough to have already reduced costs dramatically if it were straightforward.
Fusion Efficiency
Here’s the part where I earn my keep as a physicist translating technical matters. I found details about the NIF targets in a 2017 paper by Bernard Koziokiemski et al. The abstract alone clarifies much. The target is a shell of hydrogen ice 75 μm thick on a 1 mm radius sphere, cooled below 19 K. Pause for a moment to contemplate the challenges that would be involved if trying to maintain the targets at such low temperatures in a 3 GW power plant “furnace” environment.
Hydrogen ice has a density of 86 kg/m3, which in the specified volume (10−9 m3) translates to 5×1019 lattice sites (nuclei/atoms). Deuterium/tritium ice has a higher density than hydrogen ice, but the atomic spacing is unchanged so that the pure hydrogen calculation gives the correct number.
How many fusion events took place to crank out 3 MJ of energy? Each deuterium–tritium fusion event releases 17.6 MeV of energy, or 2.8×10−12 J. Calling this 3×10−12 J (among friends; makes for easy math), we find that we need 1018 fusion events to amount to 3 MJ. Each event involves 2 nuclei. We calculated above that the shell contains 50×1018 nuclei, meaning that 4% of them participated in fusion.
This event therefore produced a 4% yield. I’m actually very impressed! That’s nothing to sneeze at. The laser-induced implosion is very fast, very violent, and leaves lots of room for nuclei failing to “find” each other if not compressed almost flawlessly and symmetrically to sub-micron scale. Before doing the calculation, I might have guessed a yield orders-of-magnitude smaller.
So this news is both good and bad. Hats off for cracking into single-digit yield! But that leaves less room to improve. Even at 100% efficiency, we’d get just 25 times more energy out, or 75 MJ. That’s still not enough to pay for the price of admission (400 MJ, just for the laser part).
NIF Purpose
This avenue, therefore, seems painfully far away from achieving practical societal energy. Even 100% yield (for the present design) could not produce net energy. Even if it could produce net energy, the laser repetition rate is a million times too slow. And then, even if the laser could fire fast enough, the cost of each target is prohibitively high by over four orders-of-magnitude.
Then, we have a raft of practical considerations for turning an experimental facility into a functional power plant. No design exists at present to extract the heat produced at NIF. That’s not what it’s for—it wouldn’t make any sense to put effort in that direction. Such a design would have the unenviable thermal challenge of delivering cryogenic targets into a hellfire-hot environment. For energy extraction, tokamak designs like ITER are less unsuitable. In either case, all this to boil water. Bless their hearts.
But the NIF was never “about” societal energy. Its primary purpose is nuclear weapons research. This pesky thing called the nuclear test ban treaty means we can’t just go around detonating nuclear bombs whenever we feel like it. Surely we did not run out of South Pacific island paradises to blow to smithereens. The NIF allows study of matter at extremely high energy density. Other targets besides deuterium–tritium can be placed in the converging laser beams. Essentially, we can create the unbelievably hot conditions relevant to nuclear detonations in the safety of our own national lab.
Inertial confinement fusion (ICF) constitutes a small fraction of NIF’s laser shots. Most of the work is labeled HED for high-energy-density research. The people at NIF are under no false impression about the potential of this type of approach for generating societal energy. They know what they’re about. At the same time, why not poke? It certainly has some benefits in terms of public attention, translating to funding.
How Embarrassing
So what can we say about the public reaction to this news? Headlines in December gushed about the dawn of a new era of limitless energy. People got excited. Many of my students came away thinking it was basically a done deal—now just a matter of putting into practice. That’s how it works in entertainment: a genius breakthrough followed by immediate implementation free of complication. The emphasis is on human ingenuity, not on physical reality. In my experience, ideas are a dime-a-dozen. The hard part is coming up with an idea that can be practically brought to fruition.
I often encounter a disconnect on matters of this sort when interacting with people—whether about space colonization, fusion, renewable energy, or prospects for modernity’s continuation. I frequently find myself outnumbered. Why am I so negative about these things? The disconnect might have something to do with how information is received and processed. If all I had to go on were popular media accounts, word-of-mouth, and entertainment, I’d probably be similarly miscalibrated. But my background, training, experiences, and accomplishments enable an uncommon approach that is less dependent on what other people are saying, and more strongly tied to the underlying drivers. That’s not to say I’ll always have a more accurate take, but just that my process generally involves more independent thought and analysis than I suspect it does for most people. I’m no fun at parties.
In any case, the public reaction to the fusion story tells me a lot about our collective psychology. To me, it speaks to a sense of desperation. I think people sense that the “bad news” side of the ledger is overcrowded of late, and it’s starting to dawn on people that the future could possibly be worse than the present. This causes a cognitive dissonance in that our cultural narrative is one of progress, growth, and innovation. How can these competing visions be squared? News of fusion has the effect of temporarily permitting people to shed the anxiety and embrace the dream all the more strongly. Words that come to mind are: embarrassing, pathetic, humiliating.
What if you see a movie star across the street, overcome by excitement as they stop, look at you, and wave enthusiastically. You, of course, wave back. They see you. They recognize you as special, just as you knew all along. Only, it then becomes apparent that their movie star fling (according to the tabloids) was passing behind you. Now how do you feel? How could you fall for it? That’s the question I find myself asking about the fusion hype. It’s so obviously far from relevant, how could we (and the media establishment) fall for it?
My suspicion is that it plays perfectly into our culture’s irrational hopes and dreams. We have a weak spot in our armor for things that sound too good to be true. We want to believe the narrative (mythology) that humans are exempt from all limits, and that our ingenuity will save the day every time. We want to believe that the movie star would adore us, if only they got the chance to meet us. Instant besties!
Many in our culture truly believe in “the amazing future,” uncritically extrapolating our fossil-fueled joy ride into ever-more impressive innovations and technologies. Of course, we will someday roam the galaxy. Of course we will have warp drive (how else would we roam the galaxy?). Of course fusion is a necessary stepping stone on this path. It’s silly to imagine warp drive and teleportation without first cracking fusion. So societal fusion power has to happen, in their imaginations.
The problem is that such imaginings are not tethered to physical reality. They are driven by ideology, or I would say mythology. The physical reality is that we are living in an ecologically, evolutionarily untested paradigm that is very recent (on relevant timescales) and powered by patently unsustainable practices and resource use. The cost is rapid ecological degradation and global disruption to the biosphere. It seems quite clear that the track we are on does not lead to the stars, but to ignominious self-termination of this whacky mode called modernity. It simply does not add up, once the mythology is stripped away. The venture capitalist of nature is about to slam the door on our faces.
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“The physical reality is that we are living in an ecologically, evolutionarily untested paradigm that is very recent (on relevant timescales) and powered by patently unsustainable practices and resource use. The cost is rapid ecological degradation and global disruption to the biosphere. It seems quite clear that the track we are on does not lead to the stars, but to ignominious self-termination of this whacky mode called modernity.”
Your assessment of the NIF and ignition seems very valid. Your assessment via the statement I quoted above, not so much. There’s a broad swath of society who believe the world is becoming worse in most measurable ways. Why wouldn’t they? If you watch the news, all you see is death and disaster. Reality is far different. Death by natural disaster since 1900 has plummeted almost beyond belief. Global poverty levels have been steadily declining for a couple hundred years but global poverty also started on a steep dive really starting in 1950. This is truly the best time in human history to be alive. Pollution is a more recent reduction, but pollution is still on a reducing trendline. I’m old enough to remember what the air looked like when I lived in Los Angeles in the late 1960’s. It was terrible. In fact, my family moved from there when I was young because of the air quality. What we also know is that people living in poverty lack the ability, resources, or time, to worry about environmental issues. The greatest driver of innovation and economic wealth has been capitalism, which can be used to ameliorate environmental issues that people in poverty are unable to address. If we end in self-termination, it will not be due to anthropogenic environmental issues because humans are eminently capable of adapting and overcoming adversity.
I’ll just point out that what appears to be great for humans in the short term comes at a heavy ecological cost. Wild animal deaths due to unnatural disasters is skyrocketing. Poverty in terms of habitat and biodiversity is at an all time high. This is the worst time in non-human history to be alive (if you still are, even). These painfully human-centric views are all too common, and a chief reason why the enterprise will drive itself over the ecological cliff edge and only then realize that promoting short term human interests to the exclusion of the biosphere was a very regrettable mistake. Check out my Death by Hockey Sticks post. Your assertion that our ingenuity will solve environmental problems is not borne out by data: the “bigger” the human enterprise becomes, the more imperiled the natural world has become.
He’s backcasting to project forward; as do most economists. On that basis, I don’t need to make a will…
Do you know cares about ecology? Wealthy people. They also have more time to care about ecology. If you’re poor and every day is a struggle to survive, ecology isn’t even on your radar. It’s counter-intuitive, but in order to get people to care about the ecology we need to increase their wealth and standard of living. The greatest driver of wealth the world has ever seen is capitalism when combined with inexpensive but energy dense fossil fuels. The truth is, 99.99 percent of every species of animal is extinct. A very small percentage of those are from humanity. As we become more wealthy, we have more resources to dedicate to saving animals and the environment. We will even have resources to save species on the brink of extinction not due to humans. Overall, it’s a net benefit to humans and the planet. Unfortunately, so many people are so caught up in believing the world is getting worse that they don’t see the positives.
What the heck do you think is driving climate change, resource depletion, mineral shortages, acquifer depletion, pollution, deforestation, species extinction, rising inequality etc etc?
It’s usually the members of wealthy Western Civilization who feel this way (but that’s only the backward view, which is very misleading). Africa/India/Bangladesh/etc. themselves tell a very different story. The nature of collapse is that there is a loooong ramp-up to Peak Civilization, followed by a relatively sudden and brutal breakdown. Pretty much all non-fantasists know that all future generations will suffer greatly (and billions must die due to simple physical laws) because of the resources that we’ve stolen from them – hence, yes, we have it very good …for now.
It wouldn’t take much to pull the legs out from under society. A wide-scale EMP or three might do the trick very well. Any unshielded electronics would be promptly rendered useless. Outside of the scenario of war, the risk of wide-scale societal collapse is far far lower. Resources on the planet, while obviously not endless, have barely been tapped. There are massive swaths of land across the world that remain unpopulated and undeveloped. Poverty is continually decreasing, with inexpensive fossil fuels and capitalism being the primary drivers. Despite all the positives that too many people seem ignorant of, many people believe things are getting worse and not better. If you’re one of those, you can break out of the bubble. All this positive information is publically available. There are actually more positives than negatives but if you’re a person who only sees the negative, the world is definitely getting worse.
Err what?
Tom – good post! But I would argue that they have been working on this for 50+ years, not 10. In the February 1971 issue of Scientific American the article “The Prospects of Fusion Power” is all about inertial confinement / laser ignition, with some preliminary work having already been done at that time.
But if fusion is out, then let’s go long on fission. I’m sure our grandkids will be happy to clean up the toxic mess we leave behind.
Fission byproduct contamination cleanup is fraught with disaster and problems. There doesn’t seem to be a safe way to do it. Consider a derailed train or crashed truck transporting high level nuclear waste.
This article is so correct. In my earlier days of the 1970″s I worked for Litton- Airtron then selling NdYag laser rods to Princeton Plasma Physics Lab,
Lawrence Livermore, Sandia, KMS Fusion et .el.
Back then, all the engineers claimed beark even was just around the corner. This went on for years after. I moved down the electromagnet spectrum to Rf. Selling HPM Amplifiers to the same cast of characters. Same story a decade later.
Today, we just a baby step farther down the road. This world will not see base load
Fusion plants fir another 60-100 years.
And by that time, Thermal, Hydrogen, or SMRS will be the economic answer.
USAF/SMC Research Scientist here… agreed – except I don’t think there’s enough remaining “free energy” resources left on the planet to complete the fusion project, if, indeed, it is even possible. (magneto-hydrodynamics simulations suggest stable confinement isn’t actually possible) Lack of “free energy” resources will also strongly limit the implementation all other energy technologies.
Fusion wouldn’t involve turbines. Using Direct Fusion Drive, the energy would go directly into producing power.
https://en.m.wikipedia.org/wiki/Direct_Fusion_Drive
The article you linked is specifically talking about a spacecraft that uses fusion as a means of propulsion. This article is talking about fusion as a source of energy. On Earth. There aren’t many alternatives to using turbines in energy generation. Solar panels are an exception but generally turbines will be used in power plants.
No, there’s also Direct Energy Conversion
https://m.youtube.com/results?sp=mAEA&search_query=Focus+fusion+direct+conversion
The energy balance is even worse: A large part of the energy produced by D-T fusion is in the very high energy neutron produced, and ultimately a lot ends up as ionising radiation like X-rays. These, especially when they’re at the higher end of the energy per photon scale, are actually rather good about escaping. Meaning: you aren’t going to be able to collect them, even as heat. So any energy that ends up as X-rays you pretty much have to regard as a loss. The only way you get to achieve a self-sustaining fusion chain reaction is if you have 1000’s km of potentially reacting fuel gas to be heated by the eventual absorption of *some* of that x-ray power. Combine that with having a low enough surface area to volume ratio to be losing less heat because of that, and that’s why self-sustaining (I.e. supercritical) fusion chain reactions may turn out to be only the province of stars. And stars only occur down to so small a size: Jupiter is too small. Fusion does happen there, but it’s very subcritical. Yet we can still detect X-rays from it.
I think harnessing fusion as an engine for space vehicles is still a possibility, but I think it’ll never make economic sense for societal energy compared to using the abundant Thorium we have sensibly.
I’m not too worried about ionizing radiation – it’s the transmutation of the all the matter in the reactor (like tritium at Fukushima). We make C13 by just putting chunks of C12 into a reactor and waiting a week or so…
Did we mention the reason for the inability to achieve 1000hz with the lasers? Is it because we can’t cool them fast enough to prevent diodes self-destruction? If so, you’ll have to add some large amount of MJs to make that work. Someone commented that the NYT should have published this critique. That’s another big problem with the media. They’re so eager to get out the big stories, but they don’t have the technical resources to know what’s real. If they have to err, it’s going to be on the side of clicks, and not truth. The first article I saw, admitted the energy required by the lasers but skipped off to glory land, with no appreciation for the significance of it. I was left wondering if down playing that hurdle was a ploy by the NIL to win one for inertial confinement team, or just blissful ignorance by the media (or both).
And why do we need grass lawns, at all? Aesthetics?
How about channeling the Murphy posit; you are just talking about the laser-shot equivalent of your lawnmower; not the manufacture of it and the lawnmower, nor the mining needed prior to manufacturing, nor the energy required at end-of-life to separate and recycle component materials. We will never make solar PV panels using PV panels, either.
Why don’t you find an old push-mower? They run forever, keep you fit, and consume no electrical energy.
I use a scythe. After some practice the results are pretty good. It’s gentle exercise, similar to using a push mower, but much easier than a mower if the grass is long. Grass mostly doesn’t need to be short like a bowling green, and a scythe encourages leaving patches for biodiversity during spring and early summer. Big lawns are a poor way to use land anyway.
What I’m worried about is if you cut yourself and there are no antibiotics available. Or if you need an emergency surgery. Something like 1/3rd of all deaths came from infections in the pre-antibiotic age. My mom remembered whole towns quarantined from tuberculosis in the 1930’s midwest when she was a traveling public-health nurse in the US b4 WW-II.
Lack of antibiotics will indeed be great accelerator of mortality. Another of those ‘taken for granted’ aspects of modernity which have hugely improved our lifespans, but which are vulnerable to a breakdown of complex supply chains. But using a scythe will not be one of the main causes of sepsis – it’s actually quite hard to cut yourself with one.
Yes, I mean that with current reactor technology in use, the plants end up costing too much. Dealing with waste and potential catastrophic failures has fostered widespread NIMBY sentiment also.
Meanwhile, there is possibly enough thorium to supply electricity needs for tens of thousands of years. Surely we can solve the fusion problem (or invent other energy solutions) before fission is no longer viable.
The current generation of plants certainly involve high capital spend. Partly that’s down to today’s reactor designs, which are obliged to have so many layers of safety. However, taken over their expected lifetime the resulting electricity is not actually that expensive and very predictable, as operating and fuel costs are a small proportion of the whole.
Improved reactor designs should also allow for reprocessing of waste from the current generation of reactors, wherein the waste problem is solved by retrieving many multiples of additional energy from the same material.
I rather think that humanity will learn to live well with the energy in our environment rather than harness fusion. As Tom describes it’s a very hard technical problem. Let’s see how well ITER works, assuming it is ever built. Paradoxically, as energy becomes more expensive investment in these grand schemes is likely to dwindle.
As a civilization, we just can’t do thorium reactors, which has been known about for a very long time.
Many would disagree. There are multiple recent studies showing thorium as viable if not more so than fissionable fuels currently in use.
Just one example: https://www.sciencedirect.com/science/article/abs/pii/S1364032118305951?via%3Dihub
China is investing big in molten salt thorium, and they’ve already finished a test/demo reactor. I think there are better ways to go, but China thinks this is the best fit for them, and they have a history of dominating fields by investing heavy early and getting to market first, so I’m not going to go so far as to say they are making a mistake.
Yes. Just think EMP. We lose all banking. Internet. Heat and cooling, communications, food, transportation and medical institution’s beyond needing a band aid.
That is true Armageddon
One of the *really* embarrassing things about fission/fusion power is the low efficiency of steam turbines. Basically they’re high-tech, super-complex and dangerous steam locomotives. (Not many people know much about metallurgy or materials science – that’s where the complexity actually is in fission power.)
Few people mention the complexity of these technologies. We haven’t even shown that, as a technological species, we can safely handle fission power – so I’d be terrified of of the idea of using an approximately 100x-more-complex fusion technology.
Same here. We were promised so much, at least until the 80’s began the destruction of the promised future…
That’s true – but don’t forget that it’s unlikely that Solar/Wind can rebuild themselves, nor are they likely to easily make cement. Or much aluminum. Or even large-scale mining of the remaining poor-quality ores we’ve left for the future. So Western Civilization is definitely going away. And several billions of human bodies will need burial in the next few decades.
The main problem is materials science. Metals and alloys (used to build all reactors) have fundamental limits. (Cermets and metal-fiber composites didn’t work out except in sci-fi books.) And neutrons blow their crystal structures apart, making them weak and prone to failure. That’s the fundamental limit as to why Fission is such a disaster in large-scale deployments like Fukushima (it works OK for nuclear ships b/c much smaller). Now, adding molten salt – which chemically attacks metals – aggh! That is an utter nightmare for metallurgy. (despite anything profit-hungry startups and corporation and metallurgists trying to increase their carbon footprints might tell you)
“Metals and alloys (used to build all reactors) have fundamental limits.”
The same would apply to metals and alloys used to build anything. The purpose of engineering is to work out how best to operate within those limits.
“(Cermets and metal-fiber composites didn’t work out except in sci-fi books.)”
But for high neutron tolerance, some ceramics did work out–like the carbide ceramic shell on the fuel balls for some pebble-bed designs.
“And neutrons blow their crystal structures apart, making them weak and prone to failure.”
And yet, fuel pellets are jacketed in zirconium alloy that still retains most of its strength after an entire fuel cycle in intense neutron flux. Different materials will degrade to varying degrees at different rates. If the degradation for a given material stays within operating limits for the full life-cycle of a given application, that’s a usable material.
“That’s the fundamental limit as to why Fission is such a disaster in large-scale deployments like Fukushima (it works OK for nuclear ships b/c much smaller).”
The failure at Fukushima had nothing to do with materials degradation. But if building smaller works better, there’s no reason we can’t do that.
“Now, adding molten salt – which chemically attacks metals – aggh! That is an utter nightmare for metallurgy.”
Water attacks many metals too–especially steel and iron. Doesn’t stop us from making ships out of the stuff, or building iron-lattice towers like the Eiffel tower which is still going strong after more than 130 years. (Originally designed for a 20-year service life.) Added advantage of molten salt–low pressure, so the structures don’t need anywhere near the strength of conventional reactors which typically need to contain over 2000 psi. And multiple molten teams are designing the parts which operate in the highest neutron flux to be replaceable after short service lives. Unlike the monumental challenges that face fusion, corrosion management is an ordinary, routine, and well-established branch of engineering in which we already have a huge base of experience.
So Bill Gates is in deep do-do at Kemmerer, with salt cooling.
I thought the French had taught us that lesson.
The plant Gates is proposing for Kemmerer is the Natrium reactor. The coolant for that is metallic sodium (natrium is the old term for sodium). This is the basic kind the French attempted. Metal sodium has low corrosion issues, but it is highly combustible on contact with air or water.
TerraPower is also involved in a different kind of reactor which uses sodium-chloride coolant. (Southern Co. is doing the actual development work, while TerraPower is merely supplying the design–one it appears they simply ripped-off from Elysium Industries.) Only the second reactor is a molten salt reactor–more corrosive than metal sodium, but not at all flammable.
Thanks for your clarification.
There’s no known way to deal with nuclear waste at the current scale of fission power – let alone at the scale needed to help prevent a collapse of civilization (which would require at least 10x more reactors).
One of the greatest undiscussed problems our grandchildren are facing is ~400 spent nuclear fuel pools not being continuously maintained, say, during a (local?) collapse, and then catching fire and spreading high-level radioactive dust around the planet.
“There’s no known way to deal with nuclear waste at the current scale of fission power – let alone at the scale needed to help prevent a collapse of civilization (which would require at least 10x more reactors).”
You don’t know what other people know, so the most you can say is that you currently don’t know of a way to deal with it. And even if something is unknown right now, it might not be unknown ten years from now. Right now, multiple teams are developing molten salt fast reactors which would be able to consume the spent fuel we have now (which still retains about 96% of its original energy potential). Then they could move on to consuming depleted uranium (at close to 100%). After consuming spent fuel, DU, surplus bomb fuel, neptunium 237 wastes from bomb production and other nuclear fuels we already have in stock (enough fuel to last centuries), about 80% of the resulting fission products will be cold and stable after ten years out of the reactor. For the remainder (with a net half-life of around 30 years) we’ve already developed deep drilling technology, and the tractors for placing and retrieving payloads within those bores. The Deep Isolation team has already demonstrated how this could be adapted for burying nuclear waste deep–at a small fraction of the cost of a conventional excavation repository.
“One of the greatest undiscussed problems our grandchildren are facing is ~400 spent nuclear fuel pools not being continuously maintained, say, during a (local?) collapse, and then catching fire and spreading high-level radioactive dust around the planet.”
Nobody’s discussing it because it’s a trivial problem. All you need to do is keep water in the ponds for about three months. It’s only vulnerable to breakdown if it goes dry before then. And that’s only a vulnerability of old nuclear. It wouldn’t be a problem for molten salt reactors.
And there’s a holding pool at every old reactor complex.
I have one 14 miles South, and one 10 miles North. (Charlotte , NC is in between.)
Guy McPherson used to discuss this frequently.
Yes, me too. Can’t charge an electric vehicle, except, maybe an electric bicycle. I live in the desert, yet 1/3rd of the days are too cloudy to charge batteries. So it’s much worse than many people admit – and this is ignoring the incredible temperatures (that is, the amount of energy required) needed to create high-enough quality silicon (or other semiconductors) to allow them to respond correctly to doping the interface junction.
Also, solar cells are damaged by UV light and high daytime temperature (they sit in the sun, after all, and are almost black – of course they get hot!). Deserts are hostile environments for solar!! In full sun, a solar cell can reach 170F or higher. After several years, they will no longer work at the daytime temperatures in the desert (although they will work fine in the cold of winter). This is because photothermal-activated diffusion of the depletion zones at the semiconductors’ junction start to de-deplete – so that when very hot, the photoelectrons can jump back across the depletion zone under the hot midday sun.
Do you want to see these technologies succeed to continue with life as we know it or do you advocate for planned radical degrowth using these for triage purposes?
I would like us to be able to address some of the largest impending crises we are facing, so I guess there a sort of triage element in that. The first big problem I see is warming, but I feel like there is very little appreciation of how deeply we already are into an overshoot situation. Here’s a bit from a Nova episode that I think encapsulates it:
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JAMES HANSEN: Our estimate for the particle forcing is minus-one-and-a-half-watts- per-meter-squared. So that would imply a cooling of more than one degree Celsius.
NARRATOR: In other words, while the human greenhouse effect has produced 2.6 to three watts of extra energy for every square meter of the Earth, global dimming has subtracted about 1.5 watts, so, more than half the warming effect of our greenhouse emissions has been masked by the cooling effect of particle pollution.
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Here’s the ugly part. Most of those particulates come from burning coal. Those are also what are killing millions of people every year, so we definitely need to get off coal. But when we do that, the shading/cooling effect from all that particulate pollution quickly goes away, and the rate at which the planet is warming ramps up quickly to around double what it is now, and that higher rate won’t start tapering off significantly for at least a century. So if we end all fossil fuel emissions immediately–improbable as that is–and do nothing else, we will effectively be turning up the heat to cook the planet even faster.
If we don’t like that option (and I don’t), we basically have three countermeasures that I can see. 1) reflectance: cover as much of the Earth as we can with mirrors and high-reflecting surfaces so that as much sunlight as possible is bounced back into space before it can be converted into heat. I think we are not going to do very much of this. 2) shading: replace the high atmospheric particulates with something which can mimic its masking effects. Hazard: once we have a mask we can control, we will undoubtedly turn it up to where it halts warming, which will give fossil fuel companies free reign to continue upping the CO2 content to the point we might be facing marine ecosystem collapse due to acidification. Or 3) attack the problem at its root and draw down the CO2 that has already been released, and do it as fast as we can. And I don’t think planting a few billion trees is going to cut it, especially as we get into more droughts, wildfires, and increased demand for biofuels.
Direct air capture technology is just barely out of the lab stage, but already Oxy is building a half-megaton (million tonnes per year CO2) capture facility and has started work on a 30 megaton complex. That’s barely a drop in the bucket, but just in terms of materials involved, it would not be a big deal to increase that by a factor of a couple thousand around the world–which would put us in a position to make some real progress. The problem isn’t the materials, the problem is energy. These capture units need a lot of electricity for the fans, and a lot of heat for separating out the captured CO2. And coincidentally, a lot of the teams developing advanced small nuclear reactors are considering cooling them with fans instead of water to shed their waste heat. It’s a classic setup for piggybacking.
And of course I think nuclear could eventually help displace fossil fuels, power big cargo ships, provide a lot of industrial heat, etc. etc. but I’m particularly keen to see a couple billion people lifted out of energy poverty, increasing concentration of humanity into cities, the falling fertility rates that commonly goes with those two things, and there are some dense food systems, like aquaponics, which haven’t been able to reach their potential because of the amount of energy they need. And I think if we can reduce our numbers, concentrate our population, and shrink our agricultural footprint, that just might give the natural world the space it needs to finally start its recovery. But I don’t know whether that would qualify as ‘degrowth’ as you meant it.
The 100 million degrees C plasma metric has to be viewed in the context of how much mass is actually at that temperature. The temperature of the electrons in a 40 watt fluorescent tube is in the order or 10,000 degrees C. The gas temperature is only around 250 degrees C but the gas density is low enough so there’s not enough aggregate thermal energy to melt the thin glass tube.