Just got me thinking:
What would it take for us to get to a point where there are small, safe nuclear powered "batteries", that can supply enough electricity for a building.
Short summary: Soviet engineers installed RTG powered radio relays to support the construction of a damn in Georgia. Political instability lead to the abandonment of the RTGs. Someone scavenged the generators and removed the radioactive cores from them.
Two of the radioactive sources were discovered by men gathering firewood in the forest. They decided to bring them to their camp(!) and cozy up to them to keep warm during the night(!!). Despite showing symptoms of radiation poisoning they kept the cores on their person while loading their truck(!!!). They all suffered terrible radiation injuries.
There are more sources "lost" from the same batch which remains unaccounted for to this day.
Yeah the URSS made routine use of RTGs throughout their territory (pretty logically as it's so vast and low-density electrification can't reach everywhere), and those routinely got misplaced. Things got worse after the fall of the URSS too e.g. a helo dropped two RTGs from 50m while airlifting them in 2004.
Yes, there's a Russian movie with a guy that is guarding a weather station in the North and playing games all day. He somehow gets into a conflict with his supervisor, dissasembles a RTG beacon and uses the Strontium 90 to poison his supervisor's dried fish supply. They both get irradiated and the military cleans up the mess.
Compact electrical generators powered by heat from radioisotopes have been under development in the United States since the early 1950s for space, marine, and terrestrial uses. Essentially all the generators developed for marine and terrestrial uses have been powered by 90 Sr. This report summarizes the development work done by Oak Ridge National Laboratory (ORNL), Hanford Atomic Products Operation, and Martin Company, Nuclear Division, which led to the production of 90 Sr heat sources for use in the generators.
It was a natural choice since strontium 90 is an inevitable byproduct of operating any fission reactor, and was readily available as a coproduct from weapons plutonium production reactors. Making better RTG isotopes like plutonium 238 required additional infrastructure.
It would take some kind of complete revolution. It’s not happening.
These batteries have very poor power density and are very inefficient. The advantages of nuclear-powered batteries are:
- They generate power over a long time, decades,
- They generate some heat.
They don’t generate much power. If you have a building, you would definitely think of a nuclear RTG as a “very shitty battery”, and that’s even if you don’t care at all about radioactivity.
Thinking of these as a “battery” is also a bit misleading, IMO. These are really just small power plants, which generate heat and turn the heat into electricity. The heat is powered by radioactive decay of Pu-238, and then turned into electricity with the extremely inefficient Seebeck effect. If you had a source of heat you wanted to turn into electricity, it’s much more efficient to use that heat to turn a turbine which is connected to a generator. And if you want an efficient, cost-effictive turbine, you make it big. At that point, you have a power plant.
While Pu-238 is an alpha emitter, so it is difficult to capture the decay energy in any other way than by converting heat into electrical energy, for the radioactive isotopes that are beta emitters there is an alternative where the nuclear batteries function in a way very similar to a chemical battery.
The beta decaying substance is connected electrically to one electrode of a capacitor, while the electrons emitted due to the beta decay are able to pass through the insulating layer of the capacitor, reaching the other electrode.
Thus the capacitor is charged directly by the beta-decay and it can provide electrical energy to the external circuit.
Thanks for the insights. I was thinking if we can make nuclear power generation small, it can avoid the stigma associated with big nuclear power plants. At that point it might become a viable source of energy to replace fossil fuels.
RTGs can’t do that. Compact nuclear reactors, however, can.
The problem is that a nuclear reactor is a dynamic system, with some moving parts. It requires thermal management. It requires dynamic control. It is really hard to design a fully self-contained nuclear power system which wouldn’t require any human intervention to operate.
And even if we could, there is also a problem of waste management. Nuclear waste is not too dangerous, if you don’t touch it. It is, however, quite dangerous, if you grind it into fine particles and spray a large city with it by a crop duster. Our world is crazy. There are people like that out there, who might be interested in it. It is relatively hard to obtain hot nuclear waste from centralized large power plants. It will be really easy in the case of small building-scale reactors.
We'd need to have a lot of money, a disregard for return of investment and a lot patience: Current RTGs can do that, but they're rather expensive for heating houses and problematic from the nuclear materials POV (waste / profileration), not to mention the regulatory and licensing for using it a neighbourhood - better budget the time and money for lobbying for some legislation changes.
If by building we mean say 10 apartments, and each needs 10 kW, the RTG would need hundreds of kg of Pu-238 plutonim dioxide [1].
It's hard to cite the exact cost for that since it's not a freely traded commodity but that's a lot of plutonium. Eg NASA said that with a $75-90 million investment they can make 1.5-2 kg per year of it. [2]
Not related to nuclear, but the startup Bloom Energy was aiming this by fuel cells. A small box could power a house for a year, as they claimed. Trouble was the box internals run at very high temperatures (800°C) and there was potential for things going awry.
This is established and commonly installed technology in Japan. It's called EneFarm. Lots of newish houses connected to natural gas have these largish boxes out front. The odd name leaves most people confused.
The EneFarms used to be heavily subsidized by the japanese government in a long term program to encourage fuel cell development and manufacturing. Over time prices have decreased such that the subsidy is either already expired or could be soon expired.
The tech is near, and allows getting a bit more energy out if natural gas. The gas companies hope it will allow them to eventually reuse their pipes to send hydrogen. Personally I think the combo of cheap solar panels and 400% efficiency heat pumps will outcompete gas.
Just because you pay a positive non-zero amount for less than a quarter of the energy in, it does not mean that a device has greater than 100% efficiency, which is not possible.
If heat pumps are 400% efficient then log burners in cabins in the woods are even better.
A heat pump warms a home more efficiently than using the same amount of electricity for resistive heating. It can do this because it's not generating the heat from scratch; it's moving heat from outside to inside.
A local company has developed a heat pump with a thermal energy storage system. Not sure how they do this, but I imagine there is some sort of insulated cinder blocks on a secondary loop that shuttles heat/cold to where it needs to go.
Unfortunately by that metric other electrical heaters tend to 0% efficiency because they are not making use of the virtually unlimited energy outside the buildings.
The 400% metric let's you compare with other heaters, the 100% is kind of useless.
All energy from log burners comes from the fuel, and some ashes remain unburnt. They're under 100% efficient at converting fuel to heat. You put in x fuel and <x heat.
A heat pump takes heat from outside the system. You put in x fuel and you get >x heat. Getting more energy than you put in makes the efficiency over 100%.
Sure, a slightly irritating turn of phrase, not accurate. I didn't think it would be so controversial to hold terms of art/words with actual scientific meaning to a higher standard though.
If we're willing to be so blasé with 'efficiency' then why not, say, 'functional programming'? If it works it's functional right?
Tritium-powered betavoltaic batteries are off-the-shelf products, and have existed for decades. You can buy them today. But they can only supply a current on the microamp scale, only useful for some niche sensor applications... On the upside, these batteries are fairly safe.
You could have something like that supplies heat to a building by nuclear decay, but generating useful amounts of electricity from relatively small temperature differences is hard. You could theoretically have a steam-generating nuclear reactor in a building, similar to what you'd find in a nuclear-powered submarine, but it wouldn't be small or safe or simple, and it would require large amounts of cold water.
Small research reactors exist, but they tend to generate in the neighborhood of tens of watts.
Far better would be a Pebble Bed Reactor, which more or less fits into a couple of shipping containers and provides a building's worth of power and heat for about ten years with a similar level of maintenance as a diesel genny.
I saw a video about a recent advancement in nuclear diamond batteries. Basically look like normal AA batteries but used depleted uranium and lab diamonds to make them save and long lasting
Sadly like most similar nuclear powered energy sources this is very low density, and provides very little power, despite lasting a long time. Think microwatts.
Only really viable in deployments that need very little power, where no other energy harvesting method is available, and periodically changing out batteries is not an option.
It would be nice if you read the source, and understand what is mentioned before going all knee-jerk about banning knives. Please quote the source where it says India is "banning" anything here.
Can you explain the reason for anxiety? I read through first few paragraphs where author talked about vacuum. "Nothing" about it is anxiety inducing. But then, I grew up in the subcontinent where the ancients postulated that everything came from Shunyata (nothingness).
More accurately, that everything comes from and is shunyata (emptiness). Emptiness is also not nothingness, which is a different thing. Emptiness (of svabhava: "self existence") means infinite potentiality, since it is what makes anything possible. Nagarjuna proved that if something is not empty of self existence then it would annihilate itself and be unable to have any impact on our reality. The only reason that things can (seem to) exist is because nothing exists in itself, so it is impossible to distinguish between say, an apple, and the entire universe.
I think it’s just imagining how big the universe is…and then imagining that, but multiplied with space in between. The possible collapse of it all is a fun bonus.
A kind of megalophobia? Mixed with what cosmic horror invokes, the feeling that you are nothing in an indifferent universe. Knowing just enough about the universe to know you are nothing.
Universe is not exactly indifferent. Neither indifferent nor not-indifferent. David Deutsch offered some consolation to me, because when you take in account multiple dimensions there is also a vast quantity of Earths out there "somewhere".
The idea that there are multiple parallel earths is fun to think about, but know that it is an unfalsifiable hypothesis and arguable is outside the realm of science (and close to the realm of meta-physics).
If you could figure out the distribution of universes, somehow, and figure out the distribution intelligences across them to a high enough fidelity to predict their actions (for example, by crunching numbers with a star-sized-computer, predicting what modal source code of some universe-spanning AI in a parallel universe looks like, and running it), you could in principle bargain in a cross-universe manner that leads to both parties/universes gaining value. Say you highly value diamond, and want to turn all matter in your lightcone to diamond; you've got 99% of it, but the last 1% is extremely expensive. Your counterparty values happy sentient life, and has dismantled 99% of the stars in their light-cone to make very long-lasting artificial habitable worlds, but the last 1% is the hardest to use- but would be easier to turn into diamonds than your last 1% of usable matter, and your last 1% of usable matter is easier to turn into living things than diamond. If you could somehow both predict with high confidence that a universe containing your counterparty exists, you could both gain value by using that last 1% to help the other, in a prisoner's dilemna sort-of-way.
(One possible avenue against defection is that if I can simulate you well enough, I know by definition whether you'll defect or not.)
This whole process is called 'timeless acausal trade', and it's pretty interesting.
> (i) Mobile phone security shall not allow to download unregistered and non-verified third-party Apps in mobile phone.
> (ii) Developer mode option should only be available on engineering sample phones only. Engineering sample phones shall be made available based on special request to the phone manufacturer.
Page 5:
"The document enlists guidelines around basic security controls and is not prescriptive in
nature. The readers are responsible for making their own independent assessment of the
information in this document."
Thanks for chiming in. I am really surprised to see the grand parent comment to be the top one on this thread. I guess facts don't come in the way here when people want to collect some brownie points by self-flagellating.
