tf wrote that title… nuclear is defacto renewable
No, it’s zero emission but not renewable.
Nuclear fission is actually by definition the least renewable energy source. Even coal and oil are renewable on long enough time scales. But there will never be more uranium than there is right now.
We actually don’t have that much of it if we consider the long term future, only a thousand years or so. So nuclear is intended to be a bridge to eventual full renewable power generation and storage, an essential component in the present day but it’s still a bridge.
Another thing to consider is that nuclear is the only power source that works in deep space away from the Sun. So if we’re serious about exploring the solar system or further, we’d be best not to burn up all of our fissionable material right away.
Coal exist in the earth because back then the bacteria who could break down lignin and cellulose hadn’t evolved, so dead trees had the time they needed to compress. There are such bacteria around now, though, and that means there will never be any new natural coal.
The process to produce coal is known for 100 years now. Its just not feasible, because no one needs coal. But its reversible. No one knows how to fuse uranium.
I wouldn’t necessarily say never, it could potentially happen that a dead tree ends up in an environment that isn’t conducive to lignin-eating bacteria getting to it, and I would not be at all surprised if it has happened and may continue to happen somewhere in the world since those bacteria evolved, though they would certainly be exceptional cases and almost definitely not happening at any significant scale.
It’s also possible for those bacteria to go extinct one way or another. Again, not very likely. And if it did happen it would probably be due to some absolutely catastrophic disaster absolutely wrecking the Earth’s ecosystem completely in which case we’re probably not going to make it either, but hey, new coal!
Nuclear fission is actually by definition the least renewable energy source
But if you go according the strict physical principle every energy source is non-renewable
The sun fuses a finire amount of hydrogen, earth has a finire amount of latent heat, the moon a finire amount of gravitational inertia etc.
And there’s a little paradox if you think about it, how can fusion be non-renewable but solar, that use radiation from the sun fusion, be renewable?
A bit of a stretch maybe, but I’m considering us to be discussing whether an energy source is renewable on Earth. The Sun is not renewable, but by the time that it’s no longer viable the Earth will be long gone as well! So as long as the Earth exists, I would say that solar PV and other solar driven processes like wind and hydro are renewable.
By these standards yes, deep geothermal and tidal are “not renewable” either.
A thousand years is a massive over-estimate. Providing the 6TW or so of final energy with the stuff assumed to exist that’s vaguely accessible for costs that don’t exceed renewables’ total cost is well under a decade.
No breeding program has ever done a full closed cycle and even if it were to happen, the currently proposed technologies only yield about 50 years.
You are probably refering to thorium-based nuclear power plants. Until this day, there isn’t such a power-plant in a production-ready state. Because it’s far from simple, not only because of technical challanges, but also potentially catastrofic environmental impact. I encourge you to read more if you are intrested.
Just because you can use the same fuel twice (or even 3, 10, 100, 1000 times) doesn’t mean it’s renewable. You can’t do that ad infinitum, at a certain point there will simply not be fissile material left in the spent fuel to use, and no more will ever be formed on earth (at least not in any meaningful quantities, I’m sure eventually fusion experiments or something may start spitting out uranium, but by the point we can do that at any meaningful scale we’d clearly have fusion pretty well figured out so fission would be a moot point.) What is here is what we have to work with until we start mining asteroids or what have you.
And on a much bigger timescale (and I’m talking the absolute mind-breaking cosmic sort of timescale that’s really kind of not worth mentioning because it’s so far out from our human frame of reference so I’m only mentioning it because it’s really cool to think about,) eventually all of the fissile material that exists in the universe today will cease to be all on its own whether or not we do anything with it as it decays into more stable elements. A bit more will be created along the way thanks to neutron stars and supernovae and such, but even that slows down and stops as we inch closer to the heat death of the universe.
On the other hand, given enough time and the right conditions, every ounce of carbon on this planet- plants, animals, plankton, plastic happy meal toys, could potentially become fossil fuels, coal, oil, natural gas, etc. and can keep going around the carbon cycle. Unfortunately that’s a process that can take thousands or millions of years and we use fossil fuels much faster than they can be replenished. Even if earth becomes uninhabitable and we have to all up and leave, the carbon in our bodies and whatever we take with us will end up in a new carbon cycle on whatever new rock we end up on, and can potentially keep going as long as we do.
Nuclear is cleaner than fossil fuels but is in no way renewable, no matter what tricks we use to get the most use out of it, there is a finite supply.
Fossil fuels are dirty and not really renewable on a useable timescale for us.
Renewables like solar, wind, and hydro will be a viable option as long as the sun is shining, the earth has an atmosphere, and there is liquid water. Technically there will come a day when those also run out on us but those are also kind of prerequisites for us to live here, so kind of a moot point.
And geothermal will potentially be an option as long as the Earth’s core stays hot, so hundreds of millions if not billions or tens of billions of years, which puts us in the sort of timescale where we have to worry about things like the sun turning into a red giant and engulfing the inner planets, so we’ll have bigger things to worry about than keeping the lights on.
It’s a little bit complicated and I don’t want to write a wall of text but: Waste fuel can be recycled, if your reactor has a breeding ratio higher than 1 then it has net positive production of fissile materials. Potentially all uranium and thorium of the planet could be used.
The argument being, if you consider the word “renewable” in the strictest sense, no energy source is renewable, entropy can only increases: solar depends by the sun burning a finire amount of hydrogen, geothermy depends by earth inner heat which is a finire amount ecc.ecc. The common usage of renewable is along the line of “immensely big proportional to human consumption” and in this sense there’s a strong argument to consider nuclear renewable.
Calling an LWR renewable because somebody somewhere might run a closed fuel cycle eventually is like calling oil renewable because you can make hydrocarbons by electrolyzing CO2 and water.
It’s and absurd and ridiculous lie.
Unfortunately most reactors are not breeders and we are trying our best to lock the waste away forever which ruins any chance of recovery when we finally do migrate to breeder cycles. I like to compare our current reactors to burning just the bark off of logs and then tossing the rest in a smoldering heap, with 95-99% of the energy still retained in the waste.
Breeder reactors would indeed extend the long term viability of nuclear fission immensely, we should be using them exclusively.
No it’s not. That’s just delusional. All the ideas of a sustainable uranium fuel cycle are based on non-existent technology. Uranium is a finite resource and we have nowhere near enough of it to power the world, even if you ignore all the other problems.
there is enough U238 to last until we get there. except if you think fusion is more than 500 years away (yes, that number is out of my ass)
