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Thread: Fusion, another step closer?
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2022-02-21, 03:12 PM (ISO 8601)
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Re: Fusion, another step closer?
Does someone know the advantages/disadvantages of thorium fission? I'm not an expert, i just heared of this alternative fuel.
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2022-02-21, 03:57 PM (ISO 8601)
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2022-02-21, 04:05 PM (ISO 8601)
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Re: Fusion, another step closer?
For one, we have much more thorium 232 than uranium 235 as it does not undergo spontaneous fission. This in of itself makes a lot of safety problems a non-issue (procedures during mining, transport and reactor shutdown for example). On top of that, it produces far less waste that is also radioactive for a much shorter time.
There is however one quality of thorium reactors that is both an advantage from the current viewpoint and a reason why uranium was initially chosen instead: it cannot be used to produce plutonium 239.
From other options, typical nuclear waste could be burned up as fuel in fast neutron reactors. There are some works in that direction, but I do not know of any working power plant like that.In a war it doesn't matter who's right, only who's left.
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2022-02-21, 04:26 PM (ISO 8601)
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Re: Fusion, another step closer?
30 second version.
Thorium fission is a relative misnomer, it's not the thorium fissioning. Thorium isn't fissile, it can't sustain the fission chain reaction on its own. What you can do, is blanket a previous reactor, fission or fusion, you just need neutrons interacting with thorium. The thorium will absorb the leakage neutrons from the reactor and transmute up to U-233 which is fissile. After operating the reactor for some time, you can remove/shuffle the thorium in the blanket, take it out and do chemistry on it to extract the U-233. You then use the U-233 as the fissile element in a reactor.
The nominal advantage, particularly for India which has the majority of the world’s thorium reserves, is that thorium is much more abundant than uranium. It’s also appealing to be generating future fuel during your operation. You generate less transuranic ( the super long lived stuff) since you’re burning U-233 and not capturing neutrons on U-238.
The downsides are similar to other breeder reactors. Uranium fuel is still cheap enough it doesn’t make economic sense. You need extract the fissile material, this means you’re doing wet chemistry to pull it out which possess a proliferation risk since you can make bombs with U-233. You’re also still fissioning material and creating fission products. While the distribution is isotope dependent I don’t think U-233 fission produces considerably less or shorter lived products.
In short, it’s not a silver bullet, it makes some sense for certain countries, but it mostly just presents a different configuration of the standard risks of fission reactors.
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2022-02-21, 06:11 PM (ISO 8601)
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Re: Fusion, another step closer?
The waste thing is actually slightly inaccurate... sort of... it's complicated. As for safety problems, arguably thorium has it much worse, because the mining and transport risks are so minor compared to used fuel, and while with uranium we can just bury the waste, thorium needs handling of irradiated materials in order to work at all... mostly.
Firstly; waste. Thorium starts off lighter, so doesn't produce the very heavy isotopes that often have half lives in the problematic region. The region where they last long enough that we can't just wait it out, but short enough that they are intensely radioactive. When people say thorium produces less waste, this is what they are talking about. The second major class of waste is fission products. When fission is successful, you are left with two fragments, and they typically have more neutrons than they are happy with, meaning they tend to be very radioactive too. Most of these are either extremely long lived, or quite short lived, but two in particular are the biggest concerns; Caesium 137, and Strontium 90. They have half lives in the decades and love to get in the water. Thorium fission actually produces more of these two troublemakers.
Where it gets more complicated is that uranium fission is far easier than thorium, so comparing a basic uranium reactor with any thorium reactor is not comparing like with like. Every thorium reactor has to be an efficient thermal breeder reactor, in order to work at all. The uranium reactor designs actually used are not optimised for reducing waste, or fuel efficiency, (unless you are Canadian), so it doesn't really make sense to say that thorium is cleaner or more efficient. That's all down to the reactor. It's like saying a wet log burns cleaner because you need a very good stove to burn it at all.
The statement that you can't use a thorium reactor to produce plutonium is also not strictly true. The true statement is that you can't use thorium to produce plutonium. You can, however, run uranium in a thorium reactor instead, and that will breed plutonium. The transmutation of thorium into U233 has very similar requirements to the the transmutation of U238 to Pu239. Much of the reason our uranium designs are so 'bad' is that they actively avoid the capabilities that thorium requires.
If you really want an efficient reactor, you want a fast reactor. Fast reactors are able to 'burn' those heavy elements that result from uranium fission, meaning they sort of stop being waste. Fast neutron fission also knocks more neutrons off, meaning even less caesium 137 and strontium 90 initially. Those extra neutrons can be made to do something useful, and while it is still theoretical, there are enough to transmute away the caesium and strontium altogether, along with a few other problematic wastes. While it is technically possible to use thorium for fast fission, it is really bad at it compared to U238. Fast reactors have regularly been used for submarines, as well as a few commercial scale ones. They commercially failed because the savings from not producing as much waste did not make up for the increased complexity. I don't see why the same would not apply to Thorium. Many of the most interesting 'thorium' ideas actually work as well or better on fast reactors. Molten salt fast reactors in particular look extremely promising, doing away with the annoying molten metals they typically used.
Don't get me wrong, you can build an incredible reactor that runs entirely on thorium, but the touted problems with uranium they are often claimed to solve already have practical solutions. They just aren't used because the problems aren't actually as big as they seemed, and the novelties required to get thorium to work are just as applicable to improving uranium. Gawking at thorium's potential seems silly to me, when it is dwarfed by the potential of fast reactors to process much of the existing waste, as well as producing even less of it's own.
Interestingly there is some work on integrating thorium into existing reactor fuels (with no external breeding or post exposure processing... of the thorium at least). MOX is currently a blend of uranium and plutonium oxides, and can be used in place of enriched uranium. There is work being done on replacing some of the uranium in this with thorium, which breeds into U233 as the other fuels burn. The primary goal is not actually efficiency, or waste reduction, but stability. The goal is to create a fuel that creates more fuel at a similar rate it burns off at, while also acting as a poison at the start that disappears as reaction product poisons appear. It is aiming to make reactors easier to control and burn more evenly.
Oh, I should also mention that heavy water reactors are likely to get cheaper over the next few years too. Heavy water is a by-product of electrolysis, and we are almost certainly going to need industrial quantities of hydrogen for things like fertiliser production. It is currently gas derived, but with accurate carbon pricing and either nuclear or renewable energy (electrolysis is a good candidate for intermittent demand) should be cheaper.Last edited by Fat Rooster; 2022-02-21 at 06:22 PM.
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2022-02-21, 07:25 PM (ISO 8601)
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2022-02-21, 07:38 PM (ISO 8601)
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Re: Fusion, another step closer?
That's not what volatile means in science. I'm getting half a dozen different definitions when I search for "volatile" so it's understandable that people are confused, the one I was thinking of when I wrote was:
Volatile definition, evaporating rapidly; passing off readily in the form of vapor: Acetone is a volatile solvent.Long-term issues with radioactivity are not a matter of volatility at all - there the correct comparison is to long-term issues with carbon dioxide and other chemical emissions caused by burning coal. Depleted uranium is horribly toxic, but not particularly volatile.The end of what Son? The story? There is no end. There's just the point where the storytellers stop talking.
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2022-02-22, 02:30 AM (ISO 8601)
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Re: Fusion, another step closer?
Big con: it hasn't been invented yet and is only theoretical. Arguably the same problem as fusion power
Though there is one type fusion power that has actually been proven to work, is economical and widely used both by private individuals, companies and governments. It exploits the photovoltaic properties of certain materials by harnessing the electromagnetic radiation of an ongoing fusion reaction.
It's really heart warming and encouraging to know we have the technology to save the ourselves from oblivion but nah, screw that it's inconvenientBlack text is for sarcasm, also sincerity. You'll just have to read between the lines and infer from context like an animal
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2022-02-22, 03:49 AM (ISO 8601)
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Re: Fusion, another step closer?
Solar power has one key problem: inconsistent output. For the power grid you need a steady power source and solar panels give nothing during the night. We could work with that only if someone figures out, how to reliably store energy on up to date unreachable scales. There are works in that direction, but we are far from ready.
Also, solar updraft towers might be a better choice for the main solar power plants as they can produce electricity during the night. We have to see how the prototypes for those will work out though.Last edited by Radar; 2022-02-22 at 03:50 AM.
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2022-02-22, 04:08 AM (ISO 8601)
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Re: Fusion, another step closer?
So I take it that you know about pumped storage hydroelectricity and have a good reason to think it's more expensive than dealing with anthropogenic climate change? It's not an all or nothing deal either, the more coal we replace with anything else the better. To think that water reservoir batteries are "not great" as some excuse to not transition away from "armageddon level bad coal" seems unwise to me.
There are many alternatives to coal, like fission, solar, hydro, wind. All "have problems" but so what? Do it anyway, none of them pose existential threats to humanity, coal does.Black text is for sarcasm, also sincerity. You'll just have to read between the lines and infer from context like an animal
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2022-02-22, 06:49 AM (ISO 8601)
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Re: Fusion, another step closer?
I never said we should not stop using fossil fuels. If anything I just think that fission and in future fusion power is way better for the core electricity source.
Pumped storage plants work, but as with any kind of hydroplant, can only be built in specific places where you can have two large reservoirs with a big enough height difference, so it is not possible to use it as an overall solution for stabilizing the power grid. There is a reason people try many other seemingly worse option.
One more option for solar power is direct photosynthesis of ethanol (among other possible substances), which can be used as a fuel for cars or fuel cell power generators for example. This easily does away with the daily variation of power production and with good enough efficiency gives an alternative for oil.
By all means solar power should be developed, but it's not like it is a solution to everything.In a war it doesn't matter who's right, only who's left.
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2022-02-22, 08:00 AM (ISO 8601)
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Re: Fusion, another step closer?
There are several "concrete battery" storage plants. These consist of 30-ton concrete blocks in 'elevators'. Use the excess power during high-energy production to lift the blocks up, then let the blocks down when demand exceeds production. These are very similar to the hydro-storage systems, except you don't need a body of water.
Liquid metal batteries are another option for bulk energy storage.Last edited by Lord Torath; 2022-02-22 at 08:00 AM.
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2022-02-22, 10:58 AM (ISO 8601)
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Re: Fusion, another step closer?
The problem we really have is that electricity demand tends to be higher at night because that's when everyone has their lights on, and that situation is only going to get worse as more people charge their electric cars overnight. Pumped storage is extremely space-inefficient (you need big lakes at the top and bottom)--as an example, the Marchlyn Mawr reservoir that forms the upper storage for Dinorwig power station is around 300m across, and the maximum output of that power station is a bit over 1.7GW. Sounds a lot, but when the *average* (e.g. not even peak) electricity consumption in the UK is 35GW or thereabouts, you'd need a *lot* of Dinorwigs to cover nightly demand.
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2022-02-22, 11:40 AM (ISO 8601)
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Re: Fusion, another step closer?
If you are talking about nuclear, then you are bang on (As always, look at France). Solar isn't quite there yet though. The solar part is fine, but we do not have good enough energy storage solutions for it to be able to take over. Pumped hydro requires specific conditions. Current batteries will exhaust materials before we have enough. We are not far off, but it currently is not practical, rather than just inconvenient.
It is often misused, but easily vaporised is the definition when talking science. It is often confused with flammability and explodyness because it is often responsible for those two factors. Solids and liquids are generally very hard to get to burn, and extremely rarely explosive. Reactions can only occur at a 2d surface with high heat capacity and transfer (though dust can mean it behaves more like a gas). Many things you would consider not flammable do react quite exothermically with oxygen. Tar, for example. The major difference between tar and petrol is that petrol easily turns into a gas. Gasses mix easily, meaning they burn easily, and can also form explosive mixtures easily.
With regards to volatility and radioactivity, another reason Caesium 137 is such a headache is that caesium is fairly volatile. It boils at 670'C. A melting down reactor does produce radioactive gas, even if it is not burning. Don't know how much you care, but forgot to mention it in the last post
If it involves creating the geography pumped hydro requires, then yes. It would be more expensive. Pumped hydro is already used in the majority of sites it is suitable in, so while it is extremely good where it works, we are already approaching the limit of it's scaling. Wholeheartedly agree with the second bit though.
Wait, there are variants of those systems want to use concrete? That is so moronic. In order to produce less CO2 than simply burning natural gas, that concrete block will have to fall ~150 kilometers. That's not including the rest of the system, or the cost to charge it. That is just the concrete. It could work out, if you had a tower 500m tall, and were prepared to wait 10 years for it to even break even in terms of CO2, but I would not call it practical. The gravel based systems are significantly better, but people often overestimate how weak gravity is in terms of actual energy, and you need a lot of material if you plan to use it for any sort of energy storage. Pumped hydro is talking about moving thousands of tons for even an extremely small system.
Pumped hydro uses water because where it is cheap, it is extremely cheap.
Liquid metal is an extremely promising tech, but not deployed quite yet. I'd rather put faith in things we have already.
The thing that surprises me is how little we hear about work on intermittent technologies. Instead of having an efficient process with high capital cost, you attempt to develop a low capital cost process that is able to take advantage in fluctuating energy prices while being less efficient. Rather than faffing around with batteries to power your machine when energy is not available you simply turn it off, and because the capital cost is low you have more machines to produce when energy is cheap.
While I am optimistic that storage will get to the point that we could go full solar, I would rather not put all our eggs in that basket. If nothing else, seasonal variation in our energy supply is not great. We know nuclear works, and it fits straight into our current grid. Really we should have been building it for the last 20 years. It's not like we couldn't see this coming.
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2022-02-22, 01:26 PM (ISO 8601)
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Re: Fusion, another step closer?
I agree with all of that.
Another way to deal with solar power would be to push electricity around the world. There are always regions in daylight. I don't know how efficient that would be, but we have been transferring electricity for hundreds of miles for a long time, this would be tens of thousands, which is two orders of magnitude more, so if the efficiency is acceptable it ought to be practicable with a little engineering. Wouldn't be cheap to start with.Last edited by halfeye; 2022-02-22 at 01:27 PM.
The end of what Son? The story? There is no end. There's just the point where the storytellers stop talking.
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2022-02-22, 01:48 PM (ISO 8601)
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2022-02-22, 01:59 PM (ISO 8601)
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Re: Fusion, another step closer?
Yeah, transmitting electricity to the opposite side of the planet would need a quantum leap in technology over what we have now--we'd have to find some method that doesn't use a metal cable.
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2022-02-22, 02:29 PM (ISO 8601)
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Re: Fusion, another step closer?
Last edited by Lord Torath; 2022-02-22 at 02:31 PM.
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2022-02-22, 09:36 PM (ISO 8601)
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Re: Fusion, another step closer?
More importantly, any sort of global grid would be extremely vulnerable to disruption. Even leaving human action out of it, storms or earthquakes can already cut off whole states/provinces or even smaller countries. Trying to use a global grid to transmit solar power around means that one good typhoon could depower entire continents.
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2022-03-06, 01:32 AM (ISO 8601)
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Re: Fusion, another step closer?
Last edited by Bohandas; 2022-03-06 at 01:33 AM.
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2022-03-06, 02:59 AM (ISO 8601)
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Re: Fusion, another step closer?
If you're thinking along those lines then it would be far more reasonable (although still *WAY* beyond anything we can reasonably do at the moment!) to have a high-powered laser firing through an evacuated tunnel, because there will simply be fewer losses from such a system--provided you can get it to work.
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2022-03-06, 05:40 AM (ISO 8601)
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Re: Fusion, another step closer?
Throughput not nearly good enough for power transmission. And the losses are still an issue.
edit: Besides, even now the power grid is very delicate and not always has a decent capacity margin for sudden changes in production or use. Infrastructural endeavor to transmit power from one half of the globe to the other is way beyond our means and would probably cost more than any kind of local energy storage project let alone a solid investment in nuclear or even fusion power (when it's ready - hard to estimate costs otherwise).Last edited by Radar; 2022-03-06 at 05:44 AM.
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2022-03-06, 02:20 PM (ISO 8601)
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Re: Fusion, another step closer?
Line losses per km in state of the art UHVDC transmission systems are getting lower every few years. Right now, if the lowest losses in a real system were extrapolated to half the circumference of Earth, that would be about on par with the efficiency of hydrogen including electrolysis, liquefaction, transportation, and usage in a fuel cell.
Right now, the longest planned UHVDC transmission system I am aware of is from a proposed solar farm in Morocco to the UK.
They're both in roughly the same longitude, so it doesn't address the storage/duck-curve issue. However, the distance involved could serve as proof of concept for east-west mega power grids further in the future.
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2022-03-11, 04:18 PM (ISO 8601)
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Re: Fusion, another step closer?
As someone who lives in Tennessee I know plenty of people who would rather have had Fukishima happen in their back yard then the Kingston plants ash spill. The actually very rare occasion that nuclear power has an issue like that can be bad but fossil fuels can be even worse long term and harder to clean up.
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2022-03-11, 06:04 PM (ISO 8601)
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2022-03-11, 06:31 PM (ISO 8601)
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Re: Fusion, another step closer?
Oak Ridge National Laboratory was a nuclear development site founded in the 1940s. A lot of safety standards didn't develop until the 70s or so.
This is very, very different from talking about opening a modern nuclear plant.An explanation of why MitD being any larger than Huge is implausible.
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2022-03-11, 06:52 PM (ISO 8601)
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Re: Fusion, another step closer?
It's also false. The author cherry picked two 2 year periods out of 50 years to make his case. It was refuted less than a year later,
https://pubmed.ncbi.nlm.nih.gov/7622322/, and a 9 year health and human services assessment, https://www.atsdr.cdc.gov/hac/pha/Oa...tsheet_508.pdf, of the surrounding 8 counties showed no increase in expected cancers. Most showed lower than usual rates for specific kinds.
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2022-03-12, 12:02 AM (ISO 8601)
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Re: Fusion, another step closer?
Reminder that coal ash is really goddamn bad, more than most people would think.
Arguing that nuclear plants are hazardous when they go downhill is fine if you're comparing it to most renewables, but things like coal have inherently dangerous waste products that can't be as easily stored, and deal drastically more damage if we assume competent management on both.An explanation of why MitD being any larger than Huge is implausible.
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Purple is humorous descriptions made up on the fly
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2022-03-12, 01:09 AM (ISO 8601)
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Re: Fusion, another step closer?
I would by no means argue that coal is good. There used to be a huge mining industry here with lots of silicosis deaths, and then there's Aberfan:
https://en.wikipedia.org/wiki/Aberfan_disaster
The thing is though, these tend to be horrors that stop being a problem within a hundred years of stopping mining. Radioactivity can be a problem for thousands of years. We can't assume competant management, if there was competant management there'd be no problem with either. Just because coal can be nasty is no reason to assume nuclear is perfect, it clearly is a lot less safe than wind power or solar energy.Last edited by halfeye; 2022-03-12 at 01:15 AM.
The end of what Son? The story? There is no end. There's just the point where the storytellers stop talking.
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2022-03-12, 01:55 AM (ISO 8601)
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Re: Fusion, another step closer?
Actually, coal ash has been described in the linked video as having basically no safe solution for efficient long term storage. Meanwhile nuclear waste, which is very much not the "glowing green barrels of ooze" trope btw, has firm solutions that could hypothetically be optimized much further with means we know are viable but haven't done at scale. So competent coal management still poses a major problem in comparison.
Please do not try to dive into an argument about the semantics of what "long term" is defined as.
Also, for the moment, I am going to assume that "will be a threat in a thousand years" is a major upgrade from "will kill everyone and everything within the century". As much as I hate to say it, using nuclear as an immediate-term solution to have 500 years of breathing room to transition back into solar and wind sounds very palatable these days.Last edited by Squire Doodad; 2022-03-12 at 02:34 AM.
An explanation of why MitD being any larger than Huge is implausible.
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Purple is humorous descriptions made up on the fly
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