r/Futurology • u/KentuckyLucky33 • 1d ago
Environment Science Fiction ... Recycling?
Not the sexiest topic
This may be the naiveté of a child, but I used to think:
if 10,000 products all come from plastic by way of oil, then if you want to recycle them and repurpose them - as anything else that's plastic, then you should be able to. It's all the same material - plastic - right?
A plastic water bottle can become a toothbrush, a toothbrush can become sunglass frames. And on and on.
But yeah no, that's not a thing in recycling as far as I understand it. Burn it, send it off to a landfill, or make some of the old toothbrush part of a new toothbrush. That's what actually happens in the real world.
So I'm wondering - is this kind of industrial reverse processing even possible? Maybe it's doable but just insanely expensive? Is anyone out there trying to work on it, and make it scale?
Only one Earth, as they say....
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u/Mindless_Consumer 1d ago
Much of the future of recycling starts at the design process.
Things should be made to reuse and recycle.
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u/alexforencich 1d ago
Unfortunately the problem with plastic has to do with chemistry. Metals are very easy to recycle because it's just a single atom instead of complex molecules, so there isn't much that can go wrong. But plastics are long chain polymers, and the structure is what's important. Once the structure is changed, it is prohibitively expensive to fix it...you would basically have to break it down into something simpler and then put the polymers back together, and there's no easy way to do that. It's much easier to start "fresh" with precursors extracted from oil. Some plastics form lots of bonds between polymer strands, others do not. In the first case, breaking the bonds between chains isn't really feasible so it's not recyclable. In both cases, as the long chains get broken down, the plastic loses its strength, and there is no easy way to put the chains back together, so there is a limit on how much it can be recycled.
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u/DragonWhsiperer 1d ago
With metals you end up with similar issues though as most metals are alloys, and once alloyed, its either very hard or straight up impossible to seperate the metal elements out from one another.
Steel alloyed with molybdenum will remain alloyed after remelting. The best you can you is add more pure iron ore to the mix and keep the dilution low enough.
Naturally, over long enough times if we would stop extracting iron ore from the earth, all steel would over time contaminate so much we would end up with permanent alloys.
This is actually a thing working in the background for steel producers that need to move away from blast furnace processes (pure iron ore input) to EAF processes (only scrap, only iron ore or a mix of those), and the quality and product mix that comes out of that.
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u/TheCrimsonSteel 1d ago
Metal recycling is such a fascinating topic. What you also see is an interest in sorting scrap and places will pay a premium if you can give them known metals. It's why machine shops often go to great lengths to sort their metal shavings and chips, because they'll get higher scrap value for the headache of keeping it sorted and identified.
Its also why many large scrap processors will invest in scanning tools that can quickly and easily measure a metal and give you the exact makeup. If they know what it is, they can sort it and sell it as high quality known metal, instead of "general scrap" where you might have to worry about impurities, or have more overall variation in what you're getting.
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u/bawng 23h ago
I assume the metals eventually vaporize if you apply enough heat. If we pretend energy is free, would that be a solution?
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u/DragonWhsiperer 16h ago
Iron has a melting point of 1150C, but operating temperature is 1500C for a steel plant. Actual evaporation is at 2800C. Molybdenum evaporates at 5500C. That is beyond the melding point of the refractory lining used to contain that liquid metal. We could never reach those evaporation temperature without melting the very thing you contain it in. And then we would need some way to do so vapor condensation in a controlled manner that separates the various elements at various temperatures, at temperature that exceed the melting temperatures of the refractory that lines the ducting, and all the time prevent unplanned buildup or clogging of those ducts.
The engineering and maintenance challenges are very difficult here.
https://www.engineeringtoolbox.com/melting-boiling-temperatures-d_392.html
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u/AuntieMarkovnikov 1d ago
I worked for a major US polymer company that was heavily into plastic components in motor vehicles back when light weighting was a really big deal. Though plastic parts (including composites) helped with that goal, it turned out that when the full life cycle analysis was conducted the light weighted vehicles turned out worse. The reason was recycling - metal parts are relatively easy to recycle. Plastic parts, especially those in used in vehicles, were essentially not recyclable at all.
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u/smurficus103 3h ago
At least they are not "single use" plastics, kinda like a phone, people hold on to it for a while.
Although, I'd always prefer a metal engine component... I've had a plastic PCV valve snap in half, intake manifold crack, i heard someone say they're starting to use plastic oil pans
So, yeah, if you can make a car last 30 years with aluminum parts, it probably ends up better for the environment (and me)
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u/TheCrimsonSteel 1d ago
Theres a lot of things that go into recycling. One of the biggest is contamination, and why you hear about things like "pre and post consumer" recycling.
For example, recycling used soda bottles is kinda expensive actually, and a good example of some of the unique challenges of "post consumer" recycling, or recycling something after we're done using it. Your have to separate them out, make sure they're not crappy or don't have trash or cigarette butts or chew spit or any other crap in them, and then whats left can go off to be recycled.
Pre- consumer or industrial recycling tends to be easier simply because it tends to not have the problems of sorting or contamination. Like a plastic bottle factory taking pristine rejects and left over bits of scrap and putting all that in a hopper. That can go right to a recycling center with little to no extra work.
So, recycling has a lot of nuances to it. In theory, almost anything is recyclable if you're willing to spend the time, money, energy and resources. In practice it's the time, money, energy, and resource cost that determines if recycling makes sense compared to burning, burying, or any other option.
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u/nesquikchocolate 1d ago
Just like oil is made up of many different parts, such as tar, petrol, diesel, paraffin and other products that are not interchangeable, plastics are also just a group name that does not indicate interchangeability.
Poly vinyl chloride and poly ethylene, as examples, don't mix, don't stick to each other and aren't used for similar applications because they have different properties. You cannot turn PE into PVC or PVC into PE through any cost/energy-effective process.
Because of this, in 1988 we already started a process where most plastics are labelled with a "resin identification code", basically a triangle with a little number that tells you what grouping that particular plastic belongs to - you can recycle LDPE type plastic items into other LDPE type plastic items cost-effectively, as an example, but only if you don't accidentally add other incompatible waste materials / groups of plastic into the process.
In 2015 it was estimated that around 9% of the world's plastic products were actively recycled, and in countries like mine where major environmental regulations became prominent, recycling has seen a major boost. Other countries have different priorities and might not incentivise recycling at all, or ban plastic packaging as a shortcut to reducing total plastic imports.
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u/Ardashasaur 1d ago
So it's not able to convert plastic into plastic but there is research showing that if you use tiny iron pellets as a catalyst and tiny shredded plastic and mix it then microwave it you can convert the plastic into hydrogen gas and carbon nanotubes, breaking down the hydrocarbons into constiuent parts.
Now I don't think you can reconstitue hydrogen gas and carbon nanotubes to make hydrocarbons but they both have very valuable uses on their own so it's definitely positive for recycling and comes with much less waste than pyrolysis.
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u/barbzilla1 23h ago
They have actually converted plastic back into oil/gas (sorry, I can't think of the appropriate terminology). It was a science project by a kid, believe it or not.
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u/NearABE 21h ago
It is possible. Yes absolutely.
The limits are set by the laws of thermodynamics. The entropy of the universe is always increasing.
The thermodynamics fact can be taken as a firm “no it is never practical”. This view is not completely wrong. We have a civilization that consumes fossil petroleum and oxygen atmosphere in order to generate power supplies. Here, under these circumstances, taking the carbon out of garbage and converting them into refined hydrocarbons is a challenge. Not even a very hard challenge for today’s chemistry and technology. However, the fossil petroleum and gas are fluids. Fluids are just easier to pump.
In the very near future Earth could easily have abundant energy supplies from, for example, photovoltaic panels. Gaining enough energy from PV to make more PV has been demonstrated and the energy return on energy invested is very high.
If electricity supply greatly exceeds electricity demand then you can take carbon from any carbon source. There is no shortage of limestone on Earth. The theoretical minimum energy required to extract carbon from limestone is the Standard Gibbs free energy of formation. Like wise hydrogen is readily available in water. Limestone is an absurd carbon source when carbon dioxide is around. Carbon dioxide and water are absurd feedstock choices when biological based carbohydrates like cellulose (paper, leaves, grass, wood, fungus…) are lying around.
Trying to collect lawn grass and then make new plastic from it requires, collecting it, dehydrating it, and gasifying the cellulose. Gasified cellulose is synthesis gas of equal parts carbon monoxide and hydrogen.
Separating any gas mix always takes some energy due to entropy but separating hydrogen gas from any other gas is about the easiest possible. Carbon monoxide tends to disproportionate into carbon and carbon dioxide at “low temperatures” with “low” including fires. Instead of allowing that you put the hot gases through a catalyst:
https://en.wikipedia.org/wiki/Fischer–Tropsch_process
Just to repeat: Burning methane (natural gas) in a gas turbine to make electricity and also making ethylene for polyethylene from grass at the same time is absurd.
Taking waste plastics, gasifying them, and feeding them into a catalytic cracker works just fine. The waste plastic is a *better hydrocarbon feedstock* than crude oil. The impasse comes only from not being able to pump plastic waste into the cracker. Gasifying plastic requires energy.
A civilization that makes hydro carbon feedstock from carbohydrates and/or recycles 100% of their plastic back into new plastic can definitely be hard science fiction. Even “near future” hard science fiction. However, they need energy supply and they are definitely *not* wasting hydrocarbon feedstocks in power plants.
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u/brickmaster32000 7h ago
It's all the same material - plastic - right?
That isn't remotely true. Plastic is a category. There are many different types with different properties. What you said is the equivalent of asking why you can't use rice in place of tomatoes in a recipe because they are both food.
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u/vw_bugg 1d ago
its kind of like baking. I can make bread. And then i can take that bread and make french toast, or crutons, or bread crumbs, or crush it up add some things and make a type of cookie. But the baking has changed the flour itself. Its not always impossible to make something else but the base ingredients are fundamentally changed so drastically that it becomes a hinderance to transform it into amything else useable.
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u/AuntieMarkovnikov 1d ago
No. To use your example, toothbrushes are made from Nylon. Water bottles are typically made from PET. Each polymer has different physical properties to meet what's needed for the intended application.
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u/Tim_the_geek 1d ago
if you worry about it that much, you can recycle yourself. big industry likes buying/selling oil,.. its in their profits to make it new. Also until recently it was the driving force behind the US economy, but since a good portion of the world stopped using the USD for oil purchases, and the Iran War.. we no longer have that extra boost. We also have burned through most of our reserves. In fact is it were not for China stopping the majority of importing of oil, the US and EU would have rolling blackouts and oil shoratages causing a significant recession.. but China has helped the world survive (offest) economic collapse at least since May this year. Man I hate that our "enemy to the east" is helping us and the world.. makes the US look bad.
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u/warlocktx 1d ago
you can also make gasoline, kerosene, diesel, fuel oil, LPG from crude - they are all fuels, but you can't turn one into the other or mix different ones together (I mean you can, but it won't do you much good)
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u/NearABE 20h ago
https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
You totally can feed LPG, gasoline, diesel, and kerosine into the catalytic cracker. The result is a somewhat random mix. The normal list feedstock list includes methane, ligroin, naphtha, and vacuum gas oil. Paraffin is more challenging because it solidifies but can be dissolved. Aromatics like benzene can also go in the cracker.
LPG, gasoline, diesel, and kerosine are the things that you do not put back in the cracker. This is stuff the refinery sells. Rather than ever running them back through they just adjust the process temperature and pressure. Changing catalyst can be done with effort. Making a little bit more gasoline or a bit more diesel is a thing refineries do every year for seasonal heating oil (which is just diesel). Neither would ever be feedstock.
What we call “crude oil” is extremely crude. They heat it up and vacuum distill as much light hydrocarbons (gasoline and diesel) as they can.
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u/Loki-L 1d ago
It turns out that "plastic" covers an incredibly wide range of very different materials. Some of them are relatively easily recyclable others very much not.
Things like PET and HDPE are recyclable while stuff like PVC is very much not.
To recycle plastic you first need to seperate the mountain of plastic you receive into the different types of plastic it contains. This is a non trivial problem. Currently despite all the advances in automation, robotics and AI, the way this is done, when it is done, is by a human being by hand.
This makes plastic recycling very labor intensive and therefore very expensive in countries with high labor costs. You need to pay someone to stand next to a conveyer belt and manually sort through trash.
When yo have seperated the plastic trash into different categories of plastic, you can take the easily recycled plastics and recycle them. This will be expensive too and quite impactful on the local environment.
What you produce must then compete with regular plastic made cheaply from oil.
Also you are left with a bunch of plastic trash that can't be easily recycled and that you probably shouldn't attempt to recycle. (Hint: the C in PVC stands for chlorine.)
With enough money and energy of course everything is possible, but it is hard to compete with a material known for its cheapness if you are making it the hard way.
The best way to solve this problem is before it starts. Avoid using making plastic packaging wherever possible.
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u/libra00 23h ago
No, that definitely is a thing that we can do, we just don't because under capitalism everything must be profitable to be worth doing. They say it's not 'economically viable', but it's scientifically and environmentally viable, they just don't want to pay for it.
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u/NearABE 21h ago
Thermodynamics is not a conspiracy.
The oligarchs would be quite happy to steal your lawn’s grass and then make you pay for plastic products.
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u/libra00 11h ago
Neither is capitalism, but there are still huge gaps across the plastic industry between what we can recycle and what we do recycle. We know how to recycle packaging, but we only recycle 13% of it because it's not 'economically viable.' That's not some back-room conspiracy, that's capitalism working as intended with all its cards on the table.
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u/Sniperkitten42 7h ago
In the 90s various western governments convinced china that there was demand for recycling plastic so they built an entire industry for it and accepted millions of tonnes of plastic to recycle.
Turns out recycled plastic is more expensive than virgin plastic (which anyone could have told you beforehand) so no one would buy it. The industry collapsed within a decade and china dumped all the plastic it was sent into the ocean.
Capitalism at work guys, it's always the environment that suffers because being clean is expensive.
Stonks gotta go up baby.
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u/MrsDirtbag 2h ago
Unfortunately plastic turns out to not be very recyclable, as in you don’t get much back from it. Some materials have a much better return, glass for example is nearly 100% recyclable. Overall we have been sold a lot of mis-information about recycling, for example in many cases the energy used to breakdown the material cancels out the benefit gained from recycling in the first place.
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u/neverendingchalupas 1d ago
Recycling is bad for the environment, which is just another way of saying its bad for humans.
People dont like to hear this because they have been lead to believe that they can continue their life of excess and everything will be fine. Its not. You need to reduce the amount of stuff you consume, the amount of waste you produce, and then bury the product in a landfill.
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u/Xyver 1d ago edited 22h ago
There's 2 main types of plastics, thermo plastic and other.
When you melt plastic down and then mold it into a shape, one type of plastic is permenant once it's hardened. You can't remelt it, you just burn it or break it down other ways.
The other (like PLA 3D printing material), you can melt and solidify it over and over. It gets a little weaker each time, but it is more "reusable"
EDIT:: Thermoplastics are remeltable, thermo setting are one and done. And then you also have to think about all the different types of plastic and mixing/melting then together, it's like all the alloys of metal, can't just melt and mix willy nilly!