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Smart plastic incineration posited as solution to global recycling crisis (theiet.org)
67 points by alex_young 65 days ago | hide | past | web | favorite | 84 comments

Planet Money has a good two-part series on this (episodes 925, 926). Basically plastics are only really useful for recycling if they’re washed thoroughly (which requires water, possibly hot, using more resources), and not shipped all the way around the world. Until we have recycling facilities locally, it’s just not worth it. Using them for energy would seem to be a better option, but I think that landfill is still probably the best one.

The real solution is to reduce consumption and push the packaging waste costs back on the companies making the products.

Also mentioned in the episode—a US landfill is very unlikely to illegally dump your plastic trash into the ocean. If you ship your plastic to China or Malaysia, the possibility of that happening becomes substantial.

Given that it's incredibly easy to corrupt the batch by contamination, the washing is nearer an abrasive stage followed by very hot washing. Not only do they need to remove food remnants, but ink, labels, glue and any remains of the one time seals as found on milk cartons.

Local facilities probably wouldn't pay as margins are so thin - it depends on sending to parts of the world that are cheap. The parts of the world that have few environmental laws or enforcement and where cutting corners is too easy.

Totally agree on the real solution. Recycling came about in part thanks to companies working hard to promote it as a means of externalising another cost in place of reuse.

> The real solution is to reduce consumption and push the packaging waste costs back on the companies making the products.

And to embrace landfill. People became conditioned to think how bad it was to bury mountains of garbage (which it is), but it's far better than pumping it into the air or waterways.

What groups dump plastic into waterways?

Isn’t they simply individuals throwing their trash into waterways and it makes it to the ocean?

According to the mentioned podcast, the large garbage patches don’t just happen as a result of currents collecting random floaters into one spot; they come from countries like China just dumping whole barges out in the ocean.

Apparently it was (and might still be) a solution to disposing of "recycling" that was sent to many poor nations for processing.

What complications stop recycling centers from becoming more regional in nature?


this burning will lead to toxic gas being released that will increase cancer rate. I bet wealthy people see this as a money making proposition for their pharmaceutical companies.

The ‘smart’ in the title refers to a method of incineration without the emission of toxic gases; the air is scrubbed clean. So that money making scheme probably won’t work.

that's bs all incinerating technologies produce toxic gases. for incinerating plastic the argument is that it's less toxic than letting it sit in a landfill.

These incinerators are not your typical campfire. When your scout master yelled at you for throwing plastic in the fire, he was right because such a fire is relatively cool and has lots of incomplete combustion. Burning plastic in such fires produces a lot of nasty gases.

But modern industrial incinerators are another sort of beast. They burn hot enough to tear apart most of the nasty shit and burn that too.

I am well aware. the point is that these systems are not perfect and will lead toxic fumes being released no matter how efficient you make it. sweden is doing this and have clean air purely because of them being conveniently located under a jet stream that sends all their air pollution to asia.

Respectfully, if Asian governments are blaming Sweden for their air quality, they are pulling a fast one...

so you are criticizing them for polluting by defending a policy that dump pollution on them. talk about being out of touch with reality.

You've not provided any real evidence for modern incinerators run by first world nations polluting as you claim. All you've provided is rather paranoid conspiracy theories. The fact that you started this conversation out with tired tropes about the rich and the pharma industry should have been my first hint that this would be an unproductive conversation.

As you probably know there are problematic toxins like dioxins that stay in the environment basically forever and toxins like NOx that are no big deal because they decay rapidly to safer substances.

Molten salt oxidation.

Essentially you "burn" the waste within a molten salt bath and get "synthesis gas" (mix of CO and H2) out. https://en.wikipedia.org/wiki/Syngas Feed that through a water column to get CO2 and more H2, send the CO2 to greenhouses or algae and the H2 to fuel cells.

> Molten salt oxidation is a non-flame, thermal process that destroys all organic materials while simultaneously retaining inorganic and hazardous components in the melt. It is used as either hazardous waste treatment(with air) or energy harvesting similar to coal and wood gasification(with steam). The molten salt of choice has been sodium carbonate (m.p 851°C), but other salts can be used. Sulfur, halogens, phosphorus and similar volatile pollutants are oxidized and retained in the melt. Most organic carbon content leaves as relatively pure CO/CO 2/H2/H2O gas (depending on the feed conditions, whether steam or air is used), and the effluent only requires a cold trap and a mild aqueous wash (except mercury-containing wastes). It has been used for safe biological and chemical weapons destruction, and processing waste such as scrap tires where direct incineration/effluent treatment is difficult. The major downside of the process compared to direct incineration is the eventual saturation of the melt by contaminants, and needing reprocessing/replacement.


MSO works and TDP was a scam.

TDP was sold by Changing World Technologies as a tech that turns any waste into oil by reacting it with water. A cursory inspection reveals that this cannot work out chemically, and it didn't in practice.

The press releases contained scarce details, but did drop a few hints at what's actually going on: Stuff that can hydrolyse, will hydrolyse. This turns fat into fatty acids and glycerol, and protein into amino acids. The second stage decarboxylated the organic acids. In practice, that means fats became "crude oil", proteins became mixtures of amino compounds, and everything else pretty much remained unchanged. They even made up the bullshit term "fertilizer grade amino acids" to hide the fact that this byproduct was worthless and simply dumped. I suspect, the complaints about smell were caused by the amines in the waste stream.

In summary, TDP never worked, and it was oversold. It's not coming back.

MSO is different. The conditions in a molten carbonate are much harsher, so everything breaks down to simple molecules. Dissolved oxygen radicals can oxidize everything, including carbon black. There is no question whether MSO works, it has been positively evaluated for the destruction of very difficult wastes, including explosives and chlorinated pesticides. The question is whether it can be economical for general mixed wastes.

Interesting, I had not heard of this before. On the surface, I was very much of a fan, for it seamed like it could process a fairly crunchy waste stream. If you have a report from (not just) a government lab on the failures of the process, I would love to read it.

I'm not aware of any comprehensive report, and it looks as if there is nothing to report on. Had CWT ever turned mixed plastic waste into oil, they wouldn't be bankrupt. But they are, so nobody bothers with their "patented process" anymore.

That's the other one I usually try to mention on threads like this, but last time someone pointed out that the one company pursuing it folded. There may be some ongoing research.

On the other hand my understanding is that MSO is used today actively to deal with e.g. chemical weapons disposal etc.

I'm not qualified to give a detailed answer.

MSO happens at much higher temperatures than TDP but doesn't require pressurization, whereas TPD is essentially a pressure cooker.

Why not simply bury it? Plastic is pretty intert and non-toxic. Wouldn’t that be much better in terms of carbon sequestration?

It can also be incorporated into concrete to provide structure and fill volume

Plastic particles will end up in drains when the concrete structure gets eventually demolished.

I think you will need a source for that, how often are plastic infused concrete structures being demolished? Why would more plastic end up in drains after being used in concrete? This seems like a nonsense dismissal.

No, its not. A huge amount of reinforced concrete is repurposed on-site to make aggregates for building. This means its destructively ground down in machines and the steel is usually removed for smelting. At this point, the plastic is going to be light chaff and will disburse.

Concrete buildings have a 50 year life, but after 50, the concrete becomes aggregates, and this is going to liberate a lot of the plastic binder used.

Binder in concrete is really good, it can help in earthquake zones and fire zones to keep building integrity, its also very possibly useful for penetrating shock events on concrete which some people face. So overall I think it is sound to use known quality plastic fibres in concrete for the additional strength, but we have to beindfull of full life effect: its good for now, it has consequence in 20-50 years time.

(S.O proofreads civil engineering papers on GRP reinforced concrete, earthquakes and fire safety engineering)

Burning it for energy (especially in cogen plants) is killing two birds with one stone if the alternative is having to dispose of the plastic AND burn fossils for the heat and/or electricity.

There's still a solid chance of microplastic particles ending up in underground waters as the buried plastic degrades over time.

That almost made me laugh. IMHO carbon sequestration isn't a good solution for anything. But those who think it is should be fine with sequestering plastic in a landfill.

My understanding is that the issue with plastic recycling is that the quality of the resulting plastic goes down as it is repeatedly recycled and goes down if different types of plastic is mixed.

However, it surprises me that there aren't applications such as building, roads, ground fill, furniture, etc. where all you need is "a somewhat hard block of stuff" where the quality of the plastic wouldn't be that much of a concern.

Looking around me right now, plastic doesn't really see much use as a bulk material. It's more for specialized small objects, coatings, etc.

Food containers. Small formed inexpensive objects like straws and cutlery. PVC pipes.

Cars have a decent amount of plastic in the interior but still not as a structural element.

Windows, maybe? Though the quality would seem to matter a lot there unless you want partially opaque windows....

Enormous amounts of furniture are made of plastic. Not just outdoor patio furniture.

Storage containers of all kinds.

Fabrics. From clothes to sofas to window shades to backpacks to fake "pleather". Less and less natural materials are used in fabrics these days.

Signage such as large vinyl billboards or building-covering ads.

Big electric appliances such as vacuum cleaners are mostly plastic these days.

Cables and pipes of all kinds, both indoor and outdoor and under ground. Not big objects, but there are many of them.

Composite materials. Things like Corian (a kind of silica-plastic composite) is popular in kitchens.

You mentioned coatings. So much furniture is industrially coated with polyurethane or similar plastic polymers.

Plastic is absolutely everywhere.

Plexiglass and other brands of acrylic glass.

Heh. Reading this makes me realise that my comment was basically idiotic. I appreciate this!

I personally own tons of plastic crates, I'm just not with them at the moment, so it slipped my mind.

Its a shame that plastic isn't particularly easy for a hobbyist to experiment with. It seems like with some experimentation someone could probably come out with usable designed for chairs, desks, etc. that could then be either brought to market or open sourced.

There is a pretty good video on YouTube from a younger person recycling HDPE plastic. It is pretty easily formable at 350F, so can be melted in a common oven.


Do you need to worry about offgassing if you do this or is it generally safe as long as you melt it rather than burning it?

I love that the kid is using his parents actual oven :D

Someone recommended using my home oven for baking open my headlamp enclosure. The idea is to melt the glue holding the lens in place so you can e.g. add bmw halo lights to your headlamp. Problem is that glue is likely toxic then you’re cooking food in it later. So I wouldn’t try that, esp when an old electric stove w/ oven can be had for $50 that can run in your backyard

When my dad had a shop that is what we did, got an old electric oven. Had it setup so we could take off the door and use thermal blankets to cover large metal pieces we'd treat that were larger than could fit in one bake.

5:56 "so then, avoiding the awkwardly placed dog..."

Well done narrative and video. Thank you for sharing this.

> Windows, maybe? Though the quality would seem to matter a lot there unless you want partially opaque windows....

Bathroom windows and shower doors? Make it a feature, not a bug.


Personally it feels as if we need a better market for, well, 'not quite perfect' items, for lack of better terminology.

Not having a super shiny perfect shower door is really not the end of the world. It's gonna be covered in limescale in about a week unless you're super meticulous anyway.

It's kind of broken that we have an enormous infrastructure around brand new things whilst buying second hand or refurbished is usually a case of scouring ebay or pawn shops.

Embrace the Japanese concept of Wabi-Sabi: https://en.m.wikipedia.org/wiki/Wabi-sabi

It’s funny you bring Japanese culture because one the contrary of the article you link, the Japanese are quite obsessed with (visual) perfection. Also everything here come too much plastic wrapping, like every cookie in a 10 cookies box having its own wrapping.

The packing starts to nake sense once you consider the very high air humidity (90-95% saturation) of air in Japan & during the summer the air is both humid and hot. Unless the bag is air tightly resealable or each piece is individually sealed, you need to consume the single bag of food at once as the rest will otherwise quickly go bad in the hot humid air.


I personally find it way more comfortable to be in a sort of ramshackle environment with random bits and bobs. An old country house with idiosyncracies, nothing matches.

A perfect shiny kitchen with all the matching bits and no signs of wear - no thanks!

There's lots of institutional type furniture that is manufactured using mixed recycled plastics.

Benches and outdoor tables and things like that.

I bought a great recycled plastic picnic table a year ago. The great thing is that it has a 40 year warranty. The downside is that it cost slightly more than a virgin plastic table, and much more than most people would ever spend on a picnic table.

Plastic is being used for roads, mixed into normal asphalt to form a composite material. It sounds like the worst idea ever, though: today's roads are already feeding enormous amounts of dust pollution into the environment as we drive over them. Do we want plastic dust?

I buy recycled 3d printing filament and use it for printing stuff I used around my house. The recycled plastic so far seems strong enough for my purpose.

there was an ad on .. youtube or tv about people in east asia doing just that. Collecting all kinds of plastics in the sea and making road material with it.

A renewable energy system benefits from having stored chemical energy, to help cover variability in wind and solar. Plastic waste can serve as that energy store, if the plastic was originally made from renewable energy and carbon sources. It's like burning biomass, except it's been a bit more processed.


My major concern would be rather than this being a last resort, it becomes the first choice.

It should in my view be seen as a failure that we are attempting to make the best of, rather than any kind of success.

Obviously the calculations change once bio plastics start to take over.

Why the bias against it? I don't understand why you would think that. It's not like recycling of plastic into plastic is superior by definition. That sounds like dogma.

I think the issue is that production of plastic seems to be problematic in and of itself because it's so difficult to get rid of. Especially at the enormous scale we're doing it (a single use fork made of metal would be ludicrous).

Contrast to say, very small bits of sawdust or rocks or metal filings or whatever making their way into wastewater. I'd be interested to know the behaviour of other 'pollutants' i.e. materials that aren't especially toxic but modify the environment regardless.

You can't rely on it all being recycled by virtue of it simply existing - we seemingly don't have a solution for microplastics in clothes for example, but also, every item of plastic litter is in the environment "forever" - imagine 200 years of people chucking the odd thing out of the window, car tires, carpets, etc.

So whilst this seems to be a good solution for recycling, it may not be a good idea to allow plastic use to continue ballooning, and if you look at it through that lens we don't actually want to make disposal too cheap.

All of what esotericn said, plus oil and by extension plastic is a limited resource, it makes sense to reuse it, so yes I would say it is superior, plastic is equivalent to plastic. Co2, heat and a bit of residue, not so much.

I know human nature though. Once that shiny expensive incinerator is built, people will want to use it, for everything, and they'll rebrand it 'smart' incinerating so they can tell themselves its the 'good' solution, and pretty soon we're using more plastic than before, and releasing more co2 than before, so my support (which I do have) is very measured.

I was explicitly talking about plastics made from non-fossil carbon. Why is recycling those inherently desirable, over and above raw economic reasons (if any) for doing so?

Apologies, I thought you were talk about normal and bio plastics.

I covered bio plastics with

"Obviously the calculations change once bio plastics start to take over"

I was talking about plastics made from non-fossil carbon. These aren't necessarily "bio". For example, carbon from atmospheric CO2 can be converted to ethane by various processes, and then on to various plastics, with no biological steps involved.

Plastic containers should be made with inbuild label holders so no glue is required to attach a label reducing toxic chemical and water use to clean it before recycling

So normally I read 30 to 40 % of municipal waste is organic. There is a lot of interesting work being done in accelerating that conversion to proteins and fats via insets. Shouldn’t we couple incinerator strategies with something like this? Also with bioplastics coming the organic % is likely to go up.

Good to find better ways to deal with the plastic we have, but we should probably just stop making so much conventional plastic.

This is what Sweden do.....

"Smart burning" is still burning. Why not convert it to oil? https://news.ycombinator.com/item?id=20729477

if you use it for combined heat and power the efficiency is far higher

Thats what the Brno (a Czech city with ~400 000 thousand inhabitants) does with its trash - its incinerated in a modern incinerator plant, yielding a couple dozen MW of electricity and enough heat to run the city wide distroct heating system during the summer. During the winter it contributes about 20%.

And what will you do with that oil afterwards? It'll get burned as well, just not that cleanly.

What is the status of hemp plastic?

This is merely treating a symptom. We need to stop producing so much single use plastic and so many disposable products.

Disposable products are a relatively small part of the problem. Packaging is the biggest issue.

Packaging tape is a disposable, single-use plastic

So. Not recycling. Got it.

Sassy! Uninformed, but sassy!

It’s is substituting one fossil fuel product that is buried in the ground with a fissile fuel that’s about to be tossed in the ocean.

Would it be better to recycle said fissile fuel? Somewhat [0], but recycling is very hard and is not going to happen any time soon.

[0] recycling the plastic is only better if you also substitute the need to burn most any fissile fuels (since you could always make CH4 from the plastic) We’re not there yet, so burning plastic is probably the best we can do using scalable, easily accessible and proven technology.

Even though I support nuclear energy, I'm kinda glad plastic isn't fissile :)

Best we can do to accomplish what goal? If we’re just talking about keeping it out of oceans then thats fine. But let’s not do semantic gymnastics and call it recycling.

No semantics needed. In both cases waste plastic is transformed into feedstock for a process that would have otherwise extracted non-renewable resources.

Except one works but gives people the geebee geebes. The other one makes us forget our opulent consumption but doesn’t work and kills marine life.

Should we recycle if recycling creates more pollution than an alternative?

It’s usually seen as energy recycling.

I recently saw a bumper sticker with the words "Fueled by recycled dinosaurs". Does that count as energy recycling?

I've never heard that being counted as anything but trolling.

Old concept - recycle. Proven to not be a real thing.

New concept - make infinite garbage - burn that shit.

Good to know it's "smart" incineration - not the bad old kind. Like "clean coal" - not the bad old dirty coal.

Good news for packaging industry - infinite demand to burn stuff up to make energy.

We're burning coal and gas to generate energy. Why not burn some plastic instead? It's not like it's worse than burning coal.

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