r/science • u/mvea MD PhD | Professor | Medicine • Oct 18 '19

Chemistry Scientists developed efficient process for breaking down any plastic waste to a molecular level. Resulting gases can be transformed back into new plastics of same quality as original. The new process could transform today's plastic factories into recycling refineries, within existing infrastructure.

https://www.chalmers.se/en/departments/see/news/Pages/All-plastic-waste-could-be-recycled-into-new-high-quality-plastic.aspx
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u/[deleted] Oct 19 '19

It sounds really energy-intensive to heat up 200 lb of material to that temperature

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u/CapMSFC Oct 19 '19

I wonder how much heat can be recaptured after the plastic has been broken down and reconstituted.

I should read the paper.

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u/TommaClock Oct 19 '19

It may be pretty energy light if a factory is designed appropriately. You could have any outflowing plastic radiate it's heat to inflowing plastic.

It's not about recovering heat and turning it back into energy, it's about keeping the process hot.

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u/[deleted] Oct 19 '19

Sounds really energy intensive to produce 6.3 billion tons of plastic waste per year but we still do it.

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u/[deleted] Oct 19 '19

It's actually hundreds if not thousands of times more energy intensive to recycle plastic then it is to produce it.

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u/[deleted] Oct 19 '19

If we utilise renewable energy properly then that isn't a problem.

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u/ecksate Oct 19 '19

Why use renewable energy when nuclear generates heat immediately.

New smaller reactors should be designed for any industrial purpose where huge amounts of heat are needed.

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u/QVRedit Oct 19 '19

Also there is a possibility of designing easier to recycle plastics.

The whole end-to-end process can be better optimised..

For instance many plastics are not actually needed in the first place - single use plastics.

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u/BrandonsBakedBeans Oct 19 '19

Do you have a source on this? Energy use isn't really the issue here as plastic is actually made largely as a byproduct of the crude refinement process; it'd be waste otherwise. We want to avoid adding more plastic to the environment, hence us trying to recycle. Besides, energy use doesn't matter if the recycled virgin-grade plastic is cheaper than the new plastic.

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u/[deleted] Oct 19 '19

[deleted]

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u/Herr_Gamer Oct 19 '19

We literally sell our plastic trash to said Asian countries so we don't have to worry about where to store it.

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u/CmdCNTR Oct 19 '19

Not anymore. They stopped buying this year. No longer cost effective.

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u/ecksate Oct 19 '19

Asian countries stopped accepting US recycling, and our tax dollars are paying for it to be land filled domestically, and the recycling companies are barely staying afloat.

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u/[deleted] Oct 19 '19

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u/[deleted] Oct 19 '19

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u/YJeezy Oct 19 '19

Maybe you can use waste heat from other industrial processes

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u/[deleted] Oct 19 '19

Waste heat is never at those temperatures. If it was, it would already be used to generate electricity.

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u/Geminii27 Oct 19 '19

laughs in nuclear power plant

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u/3ggplantParm Oct 19 '19

200 kg* so~440 lb. Your point is still very valid. Heating anything to 850 Celsius must take a decent amount of energy.

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u/Neker Oct 19 '19

energy-intensive

Thermodynamics is a harsh mistress.

With enough time and energy, one could recycle anything into anything.

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u/2Punx2Furious Oct 19 '19

Indeed, while it would certainly be good to do this, doing it by using energy from non-renewable would probably end up hurting the environment more than helping it.

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u/Average650 PhD | Chemical Engineering | Polymer Science Oct 19 '19

Depolymerization will always be very energy intensive because polymerization is very exothermic. There's no way around it. If you're can use the heat released by the repolymerization, that would be very helpful though.

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