
Smart plastic incineration posited as solution to global recycling crisis - alex_young
https://eandt.theiet.org/content/articles/2019/08/smart-plastic-incineration-posited-as-viable-solution-to-global-recycling-crisis/
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orev
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.

~~~
abraae
> 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.

~~~
melling
What groups dump plastic into waterways?

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

~~~
orev
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.

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carapace
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](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.

[https://en.wikipedia.org/wiki/Molten_salt_oxidation](https://en.wikipedia.org/wiki/Molten_salt_oxidation)

~~~
sitkack
How does that compare to
[https://en.wikipedia.org/wiki/Thermal_depolymerization](https://en.wikipedia.org/wiki/Thermal_depolymerization)
?

~~~
08-15
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.

~~~
sitkack
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.

~~~
08-15
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.

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

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

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

~~~
BubRoss
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.

~~~
ggm
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)

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harimau777
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.

~~~
esotericn
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....

~~~
atombender
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.

~~~
esotericn
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.

------
pfdietz
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.

~~~
benj111
Agreed.

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.

~~~
pfdietz
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.

~~~
benj111
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.

~~~
pfdietz
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?

~~~
benj111
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"

~~~
pfdietz
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.

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basicplus2
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

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kfk
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.

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

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Anka33
This is what Sweden do.....

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

~~~
wolfi1
if you use it for combined heat and power the efficiency is far higher

~~~
m4rtink
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%.

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Dowwie
What is the status of hemp plastic?

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KozmoNau7
This is merely treating a symptom. We need to stop producing so much single
use plastic and so many disposable products.

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

~~~
chewbacha
Packaging tape is a disposable, single-use plastic

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thinkingkong
So. Not recycling. Got it.

~~~
sbdodbdjfzi
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.

~~~
thinkingkong
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.

~~~
sbdodbdjfzi
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.

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andrewstuart
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.

~~~
Flavius
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.

