Environmental impact of using an extra bag to separate out plastic vs not separating

Question

Recently I am facing a dilemma: I am living in The Netherlands and in this area it is encouraged to separate out plastic trash for recycling.
Usually my plastic trash consists of food packages and sheets (the point is: let us assume the trash itself does not contain a bag or something that can contain trash easily).

Now there are two scenarios:

1. Put plastic directly into the mixed container at my house (gets picked up on a fixed schedule and has sufficient capacity)
2. Put plastic inside a bag, and bring it to the recycling point (short walk)

As I was opening a bag to contain the plastic trash this made me wonder:

Is it actually better for the environment to separate the plastic at home, or put it in the mixed trash (which may see separation later?) and avoid the production of an additional bag. In short:

Is the recycling of 1 bag of plastic trash environmentally worth the production of 1 plastic bag to hold it?

Answer 1

Is the recycling of 1 bag of plastic trash environmentally worth the production of 1 plastic bag to hold it?

Almost certainly it is. Just for fun, I weighed a plastic bag. It's 14 grams. So if recycled plastic causes let's say 90% of the emissions non-recycled plastic causes (I'm using a really ridiculous number like 90% here, probably it's far smaller), then recycling 1 kilogram or 1000 grams of plastic causes emissions of producing 1014*0.9 = 912.6 grams of new plastics. So it's a win. (In fact, even if recycled plastics would cause 98% of the emissions of non-recycled plastics, it's still a win, and that would be 2% savings only for recycling. I'm sure we wouldn't recycle plastics if it caused only 2% savings.)

Also do note you can reuse some plastic bag you have laying around. It's not a problem to find used plastic bags.

The real problem is the short walk to the recycling point. If we assume that a plastic bag weighing 14 grams causes 50 grams of CO₂ emissions, then we need to consider how much emissions the short walk causes. I assume here it's 2 kilometers (1 kilometer there, 1 kilometer back).

An electric car driven 2 kilometers would cause 18 grams of CO₂ emissions but for example a bicycle would cause at least 20 grams, and if bicycle is 2.5 times as efficient as walking then walking would produce at least 50 grams of CO₂.

So really the walk there and back is about as bad as the additional plastic bag and that's assuming you're vegan. Someone who occasionally eats meat would cause the walk there and back to be the major problem!

Answer 2

Walk your plastic to the recycling centre (in a reusable bag).

• Your items are slightly more likely to be recycled if you sort them yourself.
• A bag can be reused many times. Your recycling point should allow you to empty your bag into a large bin -- if not, ask them why!
• A short walk is good for physical and mental health. Don't be deterred from walking because some people claim that walking emits more CO₂ than cars.

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MRF Effectiveness

As I see it, this question is really about the effectiveness of automated sorting at Materials Recovery Facilities (MRF). Luckily, I found a Masters' thesis titled Carbon footprint of recycling systems by David Palm from Chalmers University Of Technology in Sweden.

• The MRF uses approximately 1.83 litres of fuel oil and 30 kWh electricity per tonne mixed waste.

The MRF is pretty energy-efficient at sorting recyclable material, but you can probably do slightly better when sorting by hand.

• In the Greenwich MRF, the [sorting] reject rate is 3-11% [15]. The rejected material is an unknown mix of potentially recyclable materials and other waste.

In general, the "bring" system (self-sorting) results in a higher percentage of material being recycled. Single-stream recycling is less efficient (lower % of items successfully recycled) but ends up collecting much more of the potentially recyclable material because it takes less effort from people, so the overall result is more items being diverted from the landfill.

This actually exposes an interesting dilemma that often appears when trying to make environmentally-friendly choices: the most efficient solution is usually not the best solution overall! This is the crux of the debate about single-stream vs multi-stream recycling. To help understand this better, think about single-use bottles vs. reusable bottles. Reusable bottles are clearly better if they get reused, but not everyone participates equally. If you gave free reusable bottles to everyone in a city, many of them would go unused, which ends up being more wasteful! The best policy overall is to provide options for motivated people (ie. central recycling points and reusable water bottles) while also providing a backstop that makes it easy for everyone else (ie. curbside bin pickup).