My knowledge about school level physics is admittedly not that fleshed out, but we were told that it is possible to convert mass to energy. My google-fu has sadly left me for my question here 🙁
So why can’t we just take e.g. nuclear waste and convert it to energy? After that so is my understanding it wouldn’t simply exist as matter anymore and wouldn’t require to store dangerous trash if you can convert it all to energy.
In: 77
So, imagine we are talking about a different type of fuel, like gasoline. When you burn gasoline to make a motor work, it puts out actual gas emissions – the waste. You can definitely capture that, it also has mass, but the question becomes how are you going to use that gas waste for more energy? You’d have a hard time burning it.
Same thing with nuclear waste. When you use nuclear fuel, you are taking something that you can “burn” to heat up water that turns into steam that turns turbines that make electricity. The nuclear waste is not as easy to “burn”, sort of like how you would have a hard time taking the ash from charcoal and setting in fire to make another fire.
There is a difference here in that it is possible to process that waste into more fuel, but it costs money and additional resources and some energy, and then you sometimes need a special reactor to use it in. this is something called a “closed-fuel cycle”, where you just recycle the waste into new fuel that you can burn again. Some countries have actually been exploring this. I don’t remember the status of their programs but I know it’s been discussed in France, Russia and India, and several countries have plans to store nuclear waste in a way that they could recycle it in the future if they adopt similar programs and technologies.
A lot of the nuclear waste we have doesn’t run as efficiently in the reactors we have,inefficient running reactors can be dangerous
So a lot of the fuel rods we throw out as nuclear waste is just not compatible with the main reactors we use… there are designs which use some forms of fuel rods longer but we tend to not have those reactors.. mind you reactors are expensive and take years to build, so not like we have those ready on demand.
Another issue is: nuclear waste is a big big umbrella term.. a lot of it can be old gloves, metals, irradiated items, waste water and such.. it is pretty difficult to derive energy from that…
There are very specific rules about *how* you can transform mass into energy. We call those rules “physics”. Right now, our nuclear reactions convert about 0.1% of the fuel’s mass to energy, but even this only works because of the specific way this particular fuel happens to be. The remaining materials are radioactive and there are no easy “reactions” we know of that let us get more energy out of them. This isn’t the best we can ever do according to the laws of physics, but it’s the best we know how to do with current technology.
If we ever learned how to easily & efficiently convert any matter into pure energy with 100% efficiency, we could power the entire world off of a few hundred pounds of stuff per year. Right now, we only know how to do that by combining matter with antimatter to annihilate it, but there’s no nearby natural source of large quantities of antimatter; we have to make it ourselves, which takes at least as much energy as it eventually releases when it annihilates (likely hundreds or thousands of times more due to inefficiency). It’s like a battery: you have to spend energy to charge it, so the energy you get when you discharge it isn’t really “free”. If we had a magic portal to a world made entirely out of antimatter, we could do what you’re describing.
For some reason none of your comments show up, I just get a notification that I got a comment, but then if I want to open it “Comment is missing”. Weird
It’s more proper to say that mass and energy are the same thing. But that doesn’t mean that it’s easy to convert mass-energy in one form to mass-energy in another form, or that it means anything can be freely converted into anything else.
In particle physics, which is the level we need to be operating on to talk about these things, we say that certain values are *conserved* – they don’t change in any reaction. You might have heard of things like conservation of energy, mass, or momentum (which are all conserved in all common everyday processes), but there’s a long list of conservation laws at the level of particle physics.
Among these conserved values is one called *baryon number*, which is (for ordinary matter) just the number of protons plus the number of neutrons (if you had antineutrons or antiprotons present, they’d contribute -1 to this number). While we have pretty good reason to think this number might not be conserved in *every* possible interaction in the Universe – namely, that our Universe contains matter and not antimatter, so *something* made more of one and not the other – no known actual reaction we can conduct here on Earth changes baryon number. Nuclear reactions can change protons to neutrons or vice-versa via beta decay, but that doesn’t change baryon number (since both protons and neutrons contribute equally to it).
That means we can’t just make materials like atomic nuclei vanish into thin air – they’re made of protons and neutrons, so getting rid of them would change baryon number (which we do not know how to do, and which may be impossible).
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Even if we did know of such a reaction, that doesn’t mean it would be easy to actually conduct.
We already know of reactions that can convert the atomic nuclei in nuclear waste to less harmful forms. So why don’t we do them? Because they’re very hard to do. They require a lot of energy, exotic materials, long processing times, etc, and we have to make those reactions happen to a substantial portion of the billions of billions of billions of atoms in a typical chunk of material.
For example, one major long-lived component of nuclear waste is [technetium-99](https://en.wikipedia.org/wiki/Technetium-99). If we could just stick a neutron onto this nucleus, we’d convert it into technetium-100, which decays very quickly (half life about 15 seconds) into stable ruthenium-100. No physical law prohibits this reaction. But the fact that we don’t do it suggests that it’s probably a hard reaction to actually accomplish in practice – I would guess, though I don’t know, that technetium-99 just doesn’t like to absorb neutrons very much.
We don’t know how to take any old scoop of mass and convert it into energy. We do know how to do very particular processes.
For instance, fissioning an atom of U-235 produces a couple of smaller atoms, plus a couple of loose neutrons, all traveling at high speed. If you add up the bits produced, their mass is very slightly less than the original atom.
https://en.wikipedia.org/wiki/Nuclear_fission
A lot of the fission products are unstable; in time they’ll decay, releasing sub-atomic particles, and again there’s a loss of mass. In some cases, this production of energy has been used to power small devices, but it’s not cost-effective for general use.
https://en.wikipedia.org/wiki/Atomic_battery
We generally can’t just convert mass to energy willy-nilly. There are only very specific ways we can do that, and nuclear waste is *waste* largely because we can’t do that with it (or do anything else useful with it).
Basically, in order for nuclear reactors to work, they have to be fueled by nuclear material that will undergo [fission](https://en.wikipedia.org/wiki/Nuclear_fission) when struck by a neutron and will release more neutrons in the process, creating a chain reaction that can be controlled to release useable energy. A neutron hits the nucleus of those atoms and the nucleus breaks into two smaller nuclei, which releases *A LOT* of energy as well as a couple more neutrons that can go and hit more nuclei, sustaining the chain reaction. A small percentage of the original mass is converted to energy and the rest of the mass is left over as waste, in the same way that ash and some gasses are left over after you burn a log.
Only some specific types of atoms will undergo fission when struck by a neutron *and* spit out some more neutrons to keep the process going. Nuclear waste is stuff that doesn’t have those kinds of atoms in it any more and isn’t useful for some other reason.
Because we currently don’t have the ability to turn any amount of matter into energy at 100% efficiency. The only way to do that is with antimatter, and we can’t make antimatter without putting in the same amount of energy to start with. In other words, mass can be converted into energy, but we can’t convert mass into energy.
The amount of mass converted to energy within a nuclear power plant is actually very small, but courtesy of E=MC^2 even that small amount of conversion translates to a lot of energy. That’s in part what makes nuclear power so appealing is that you need very little material to produce a lot of energy.
So a fuel rod doesn’t evaporate or get burned the way that gasoline or coal does for example . Even then gasoline and coal still produce waste primarily in the form of CO2.
Nuclear waste are the byproducts of reactions, fuels like Uranium that have decayed or been spent and now contain contaminants, lighter radioactive elements produced in the reactions. Fuel rods typically last around 5 years then they are depleted and are no longer suitable for power generation. But the remaining material is still very radioactive and has to be disposed of safely.
Some nuclear material can be recycled and re-used, but it still results in radioactive waste.
For the same reason you can’t just take energy and concert it into, say, cake. The equation you’re referencing tells you how to determine the amount of energy created when you turn mass into energy, it doesn’t guarantee that you can at-will convert one into the other. If you can devise a nuclear fusion reactor which works on trash, as you fuse that trash into some other byproduct, not all mass will add up. When you measure the missing mass and multiply it by the speed of light squared, you’ll find out how much energy the reaction yielded.
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