[ddoeth]

In 2021 there were 51 Million tons of plastic waste produced in the US [0], which is about 150kg per person.

Burning that is creating between 264 and 750kg of CO2 per person and year, definitely not insignificant.

I'm not saying that big corporations are not responsible for a huge chunk of the emissions, but getting away from using so much plastic is not hurting.

[0]: https://www.statista.com/statistics/1339439/plastic-waste-ma...

[toast0]

If it's used to generate electricity or usable heat and not only to get rid of it, plastic would substitute for another fuel, so it's not as simple as looking at co2 from burning plastic vs co2 from dumping it in landfill.

I don't have numbers, but if burning plastic replaces some coal or fracked natural gas, that could be a win, all things considered.

[tsimionescu]

Burning plastic is both dirtier and less efficient than burning at least oil and natural gas. So you will actually pollute more (both CO2 and various other byproducts) by burning plastic than by burning oil and methane to get the same amount of energy out.

Not to mention, to get usable energy out of the plastic, you have to invest lots of energy for recycling it first - you need infrastructure and education to collect it separately from other trash, you need additional processing to sort it by type, to clean it of many other residue, etc.

And evwn if you do all that fairly efficiently, you're still never going to collect a large percentage of the plastic people use. So any extra environmental impact from plastic in landfills will still be there and need to be resolved.

[toast0]

> Burning plastic is both dirtier and less efficient than burning at least oil and natural gas. So you will actually pollute more (both CO2 and various other byproducts) by burning plastic than by burning oil and methane to get the same amount of energy out.

My argument is not that burning plastic is more efficient than burning whatever fuel. My argument is that extracting, transporting and burning waste plastic may be more efficient than extracting, transporting, and burning whatever fuel. Waste to energy might need a lot less transportation if the plants are near where the waste is generated and/or where it is already collected.

> Not to mention, to get usable energy out of the plastic, you have to invest lots of energy for recycling it first - you need infrastructure and education to collect it separately from other trash, you need additional processing to sort it by type, to clean it of many other residue, etc.

There's already sorting and education for recycling, so the question becomes what's the incremental input needed to get a usable waste to useful energy pipeline.

> And even if you do all that fairly efficiently, you're still never going to collect a large percentage of the plastic people use. So any extra environmental impact from plastic in landfills will still be there and need to be resolved.

Yes, but I don't know how that relates? My argument is that the emissions of burning plastic for usable energy might not be as bad as it looks because it would reduce lifecycle emissions from (direct) fossil fuels. That's not an argument for or against burning plastic, it's an argument that we need to get marginal emissions numbers for the alternatives, and if emissions is the only criteria, then it would make sense to burn plastic in cases where the marginal emissions are in favor of burning it; but even that wouldn't be universal. It might make more (or less) sense to setup trash for energy plants in isolated locations where transport of other fuel is difficult; it almost certainly makes less sense to setup trash for energy plants in places where natgas is a waste product, natgas is a clear choice there.

[BurningFrog]

I don't doubt your numbers, but we are (or at least I am) talking about plastic bags.

I would guess they are less than 1 of those 150kg/year.

> Burning that is creating between 264 and 750kg of CO2 per person and year, definitely not insignificant.

Grok says total US CO2 emissions are "approximately 13.83 metric tons per person". I agree that 750kg (0.75 ton) is significant, but I don't thing plastic bags even affect the last decimal of that number.

[tsimionescu]

Why would we discuss plastic bags exclusively? Singling out one item like this makes little sense - the problem is the aggregate of all plastic we use, not specifically one item. If we only used plastic for our shopping bags, we wouldn't be having this discussion at all.

[BurningFrog]

My original comment was to a post claiming that "a few cents doesn't represent the actual cost" of a plastic bag.

It's far from the most important issue, but it was the one I had a disagreement with.

It sounds like you agree that plastic bags are not a big problem.

[Tronno]

How can burning 150 kg of mass create 750 kg of mass?

[jmb99]

The oxygen is not contained in the 150kg of plastic, it’s pulled out of the atmosphere. You’re actually “burning” substantially more than 150kg if you include all the reactants.

[bornfreddy]

Burning takes oxygen from the air so it makes sense that the released mass would be higher. Every 12g of C is tied to 32g of O to get CO2. However I would expect the number to be around 500kg (quick calculation) max.

[cyberax]

Polyethylene is roughly CH2, and burns into CO2 and H20. So 1.5 moles of oxygen (O2) for each mole of polyethylene. The molar mass of CH2 is 14 and oxygen is 32, so 1 kg of CH2 will result in ~4.5kg of CO2.

[bornfreddy]

How do you figure that? 14g of CH2 results in 44g of CO2 (water we can ignore), so 150kg of CH2 becomes ~470kg of CO2. 1kg of CH2 would give ~3.1kg CO2. Or am I missing something?

[cyberax]

Ah. I didn't ignore the water. D'oh.

[kolinko]

Otoh, if our emissions would be only 1 ton per person per capita, it would bring us close to paris agreement goals.

Also, scrubbing 1 ton co2 is around $600 with current tech if I’m not mistaken.