Life cycle assessment of enzymatic PET recycling
nrel.gov
nrel.gov
I hope this technology can fix the problem, but I've seen more of these revolutionary technologies in the news over the last decade. They all promise to make plastic recycling viable and say it's really going to happen this time. Only being able to recycle PET is a nice start but in practice humans absolutely suck at separating waste (and companies constantly mix plastic types, making it even harder if you really care).
I don't see any way out other than reduction of plastic use. So far, the entire plastic separation and recycling process is built on lies and deceit to make consumers think they're being more environmentally friendly than they really are. I'd be amazed if this plastic recycling technology of the month will finally chance that.
The rest is correct though and it will most likely be down-cycled, my personal strategy I have been using without going crazy is:
- Home Compost bin (this gets rid of 90% of my waste and makes the next steps less gross)
- split remaining waste according to my recycling program: cardboard, metals, glass, plastics, paper, e-waste
- cardboard/paper about half goes into compost, rest should biodegrade so vaguely ignore and hope for the best
- End of each week look at what it going into recycling (dog food containers, salad bags, sauce containers etc.) and try to find a zero-waste alternative or tell the company you are considering moving and if they have any plans to improve their packaging infrastructure
I am not an expert in this area, so would love other people to correct any mistakes, it's really hard to go zero-waste or think about the right way to solve this problem without getting overwhelmed.
Recycled plastic also gets brittle as you recycle it. Nothing in this Plastic story is anywhere near as 'circular' as it is with glass or metal recycling.
A bottle from 100% recycled PET pettles has a deep dark grey colour because they cannot perfectly control plastic colouring in recycling. So those pristine transparent bottles are 100% guaranteed not from recycled pettles.
It really is a con through and through. We need to ban single-use plastic, everything else is noise.
The major blocker at the moment is the lack of recycled PET to use.
So all the people undermining the work by telling folk not to bother recycling their bottles isn't really helpful, unless you are trying to support the fossil fuel industry.
https://www.packaging-360.com/en/current-topics/coca-cola-in...
There is no 'work', plastic is cheap for the packager, expensive for our environment. The industry has setup a marketing compaign to divert attention away from all the externalized environmental costs of plastic.[0]
You are right that I want to undermine this effort because what I want is a full ban on single use-plastic outside medical/laboratory applications.
I highly recommend this PBS docu on the PR aspects around Plastic:
[0] https://www.pbs.org/wgbh/frontline/documentary/plastic-wars/
Local councils are often convinced that a lot is recycled, but it is mostly recycled on paper, not in practice.
Obviously this might not stretch to other towns and cities.
It still seems like a good idea to keep separating plastic in recycling. At least some of it does get recycled, and having the plastic already available in a separate stream should make it easier to encourage additional programmes. However, the quoted numbers are probably very optimistic.
It's a shame that they do not link to the direct companies so you can trace the waste to completion but it looks like a good deal of it is not getting shipped outside of the UK.
I believe there are a couple of bills being proposed to also stop this practice completely, although I don't know how effective they will be.
This seems to be a popular myth, but the reality is a bit more complicated. In the EU around 40 percent of plastic waste is recycled (it tends to vary from year to year, sometimes it's a few percent more, sometimes less).
That is obviously not perfect. But it is also not nothing, and clearly does not support the idea that plastic is "barely being recycled".
The number is much lower in the US, but from that I wouldn't conclude that plastic recycling is "built on lies", but that the US needs better waste regulation.
Reducing plastic usage is generally a good goal, but it won't be reduced to zero, and we need better ways to handle the rest.
Recycling not being economical betrays this reality. It's simply insanity to recycle, unfortunately in most places it's legally forced.
Film plastic, is not recyclable except for a few cities in the US. It’s mostly garbage.
“Please recycle” is slapped onto every piece of packaging regardless of consumers ability to carry out the recommendation.
Many people think that rich countries ship most of their plastic waste overseas. But is this really true?
The short answer is no: many countries export some of their waste, but they still handle most of it domestically.
Let’s take the example of the UK. In 2010, it generated an estimated 4.93 million tonnes of plastic waste.9 It exported 838,000 tonnes overseas.
That means it exported about 17% of its plastic waste. That’s a substantial fraction – nearly one-fifth of it.
Imagine throwing a bunch of waste plastic in a reactor. Some is PET. Some is HDPE. Some is polycarbonate. Some is polystyrene. Some is other random polymers. Some is “compostable” material, and some is probably a horrible mix of plant fiber and fluoropolymers. Some is bamboo that got mixed in by accident, and there’s also some bits of food and crayons and other debris in there. Add a mix of enzymes and apply the right temperature, humidity, etc.
Out comes a mix of valuable monomers, various contaminants, and the enzymes that survived the process. And a whole lot of unreacted feedstock that simply wasn’t the right feedstock.
If you can separate the valuables out of the output mix, then maybe this whole enterprise pays for itself.
Otherwise actually obtaining a clean stream of PET to recycle seems potentially challenging.
At the end, you always need to separate, the process engineers will have to figure out what is the best method (washing, crystallization, distillation or direct reaction to build longer polymer chains, ...).
> Sourcing thermotolerant poly(ethylene terephthalate) hydrolase scaffolds from natural diversity
If you're referring to HN, there is no formal review process — it's just upvoting/flagging. If a title issue is caught early enough, the submitter can change it. Sometimes @dang comes in and cleans things up.
> Scientists Discover Enzymes That Could Make It Cheaper To Recycle Waste Polyester Textiles and Bottles Than Making Them From Petroleum
The subtitle is also quite helpful:
> Using Machine Learning, NREL-Led Team Discovered Variants of 'Plastic-Eating' Enzymes Adapted To Deconstructing All Varieties of PET—Even Durable Crystalline Varieties
Also I'd suggest avoiding cheap snark like that, even when you're actually right it's still not a good look.
Just to be clear, I had the exact same confusion that 0xTJ had about the referent of "them" in the sentence. If 0xTJ hadn't commented already, I might have made a similar comment myself! I see the title has been changed, although honestly I find the new title rather opaque.
That said, it is a bit concerning that this could escape into the wild. Plastics are harmful long term but it’s crucial to society that they don’t just start degrading.
I guess call it indoctrination since reuse, conservation, recycling is something taught to kindergarteners, but even at face value the lifecycle obviously a cost -- trash management, elegance (due to litter, and bad packaging), the risks of petroleum mining/hydraulic fracturing, presumably greenhouse gas emissions, microplastic contamination, risks of sloppy chemical engineering/benzene contamination... all costs centered on crap that mostly sucks as a product to begin with... an idiotic matryoska doll of nested garbage.
The requirements get tough at those scales, for the full life cycle I suppose, iterating on any component effectively is a lifetime of work. Oh you can melt it, what about nonremovable contaminants? how much energy input did that cost? I don't see any clear-cut solution except to eliminate subsidies at a solution-dependent rate.
There's some plastic in there, eg for the keyboard. But removing 90% of plastics would solve 90% of the problem they pose. No need for purity.
(I'm just playing devil's advocate here. I don't actually think plastics are necessarily all that harmful.)
Even reducing them doesn't make that much sense. The amount of energy needed to recycle metals is generally much higher.
Yes plastic ends up in the ocean. But most plastic waste in the ocean comes from recyclables shipped from first world to third world countries with poor refuse control.
With that in mind being able to recycle plastic cheaper than creating it from oil would be an economic and environmental win.
As a small factual change I can not find any evidence for the statement that most plastic waste comes from shipped recyclables. I'd love a source for that.
Almost all plastic recyclables in the US is shipped to Asia and Africa. It’s simply not profitable to process here.
From the article:
> Recently, however, China has made efforts to curb waste.
> For years the country had imported millions of tons of recyclable waste from overseas, but a growing recycling burden at home prompted the government to shift its policy.
>90% of river-borne ocean plastic comes from 10 rivers in Asia and Africa
Sounds like it isn't profitable there either, so why are we shipping it
China’s change in recycling policy was caused by, among other reasons, a documentary on the workers who sift through the countless volumes of plastic waste. It’s quite sad: https://m.youtube.com/watch?v=6qZwo6U5YFY
Can we stop pretending that whatever bejing decrees becomes reality in the country it claims to rule over? Its a nice play-pretend facade and the socialist inspired reality below is usually quite dystopian..
We pretend to recycle and they pretend to care..
I'd like to see a source for this because I don't believe anything of it. I only found an article saying it's not true https://ourworldindata.org/plastic-waste-trade
> Data for January showed that exports of scrap plastic from the United States edged upward, to 48 million tons from 45 million tons the previous January. Exports to poorer nations were virtually unchanged from a year ago, totaling 25 million tons.
If these larger export numbers are correct, then the estimates in the article you provided should be multiplied by a factor of 10 at least.
[0]: https://www.nytimes.com/2021/03/12/climate/plastics-waste-ex...
The principle of harm reduction dictates that society should take a few steps back and figure out what's going on.
Why do we owe it to the future? We can just stick the plastics in a land fill and deal with them later. They don't degrade (much) after all.
Perhaps oil will become expensive enough, and recycling good enough, that it will makes sense to mine landfills in the future.
(I agree that putting plastics in the ocean or so is probably not a good idea. But that doesn't mean recycling is the only alternative, especially when it doesn't make economic sense.
Btw, most plastics also burn well. So waste-to-energy plants might also make sense.)
Recycling plastic is pointless.
>Enzymes that could make it cheaper to recycle ___ than make them from petroleum
Should be maybe "plastic bottles and textiles"
A single valley in some remote area can easily swallow millions of tonnes of plastic
Expensive, energy utilizing recycling processes seem less environmentally friendly while also leaving more fossil fuel available for combustion use elsewhere
“Somewhere in the future, mankind has depleted all energy and fuel sources, however they have somehow engineered a way to use human excrement as fuel. People started to build the new city by making new energy with their excrement. Soon after, the city's leaders announced two legislations to generate and control the new energy; including installing ID chips in each citizens' anus to monitor the defecation level; providing an addictive juicybar to citizens in return.” (https://en.wikipedia.org/wiki/Aachi_&_Ssipak?wprov=sfti1)
Such stories were used explicitly by the fossil fuel industry at those concerned with the new plastics back when they were introduced.
https://www.dw.com/en/plastic-recycling-a-myth-as-packaging-...
I will still stand by the argument that recycling is impossible. Entropy can't be reversed in any way economically, chemically, or socially.
With plastic the answer is mostly no so far, but these enzymes have the potential to change that, maybe. With glass, steel, aluminum, it’s cheaper to recycle than start from ore.
It's effectively misinformation, because EVs are already better than ICE and just boring improvements to existing technology will provide improvements over the next fews years and decades.
But, a) people hawking a new innovation need to grab eyeballs, and b) people fighting the future have saturated the media with BS to stop progress on EVs, renewables, recycling etc. and those two things combine to become potent misinformation.
Recycling is already cheaper than making things from petroleum. It only doesn't happen in places where people think they can push the cost onto someone else. They don't realise that they are someone else's someone else and will end up paying the price they think they have cleverly avoided.
Amusingly, the voices that have said "recycling plastic is impossible" have been so succesful, that there's now democratic support in many places for just banning many uses of plastics. Which was an unintended impact of these petroleum fueled lies. They've recently switched to attacking plastic bans, by promising that tech like this, will make plastic recyclable in the future.
Whether pro or anti recycling, they remain consistently anti-regulation.
>...quick to charge... >...EVs are already better...
For whom? In a city, with short trips and reasonable climate, then sure. You haven't provided any reason or information as to why what you are claiming is true.
As for recycling, you may be surprised to know that in the US it has mostly never happened. Companies found that a simple arbitrage could be completed by shipping away "recyclables" to the third world.
Recycling is a corporate check mark, so corporations pay a premium to add a "post consumer recycled waste" label on their product knowing American virtue & status signaling is powerful enough to make it a cost effecting advertising strategy.
Nowhere have I found information indicating recycled plastics are cheaper than new petrochemical plastics. Plastic is unbelievably cheap.
It's hard to have that conversation if people only care about their next months out of pocket payment. Google whether gas heating is cheaper than heat pumps and you'll find discussion about what is cheapest for ordinary people with the current fossil fuel subsidies. But any simple economic analysis shows it's obviously better to shift to heat pumps and well insulated homes and so sensible countries do that, and reap the benefits.
You'd have to invent some insane conspiracy theory about how climate change wasn't even happening, and all the scientists are secretly conspiring to undermine society in order to stop that, but who would believe that?
You could also acknowledge that climate change science and climate change politics hold a rather different set of "beliefs", we can call them, the solutions offered are hardly the same and are not entirely justified in either case. Particularly when the known cost to humanity by effecting these solutions (bad) must be weighed against a possibility of a less desirable future based largely on statistical extrapolation.
We might also say there has been a fair number of Chicken Littles wildly exclaiming this and every previous decade to be (/was?) our last on earth.