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[GreenYes] Re: Are degradable plastics zero-waste?


This is exactly the kind of debate the Zero Waste community needs to be
having right now regarding biopolymers. I support them for many reasons,
but that doesn't mean there aren't issues to be dealt with... and in my mind
the primary one right now is the "recyclability" issue versus the
"compostability" issues.

I asked my resident composting expert about what you said and here was his

"I can't verify that PLA breaks down into CO2 and water, but it appears
Peter has done some homework so I'll take his word for it. No compost
facility manager will be seeking out a PLA feedstock for the value it gives
to the compost - that's safe to say. But I think Peter's criticism should
be with the marketing angle Cargill has taken, not the ZW movement. What he
considers to be the "only" value of PLA is to me the key to ZW - that it
makes the composting of other materials (food waste) easier. He's talking
about a quarter of the waste stream - that's a pretty big "only"! For the
purposes of the ZW programs that we have in place, PLA is the difference
between success and failure. So, the PLA marketers want to sell to
companies like Biota that would otherwise use recyclable containers - if
Peter is right that PLA compares favorably to plastic in its recyclability,
then we are absolutely on the right track in pressing Cargill to come up
with a recycling solution for it. Zero Waste does not mean zero sum energy
use to me. Everything we do takes energy that we don't get back...until
we're powered by renewables!"

So, at Eco-Cycle we have experienced first-hand the power of using
biopolymers with food services at public events, and it is a powerful
demonstration of how design and a little effort can get mixed organic waste
out of the landfill, thus protecting groundwater and air quality. The public
loves the idea, learns more about "composting" and it's values in five
minutes than they've learned during their whole lives (why? Because they are
so CURIOUS about the biopolymers that their minds open up and embrace the
new information!)

Anyway, I think your points are well considered and this sort of dialogue
needs to keep happening so that Cargill and the rest of them LEARN FROM US
what the key issues are as this industry grows.

Eric Lombardi
Executive Director/CEO
Eco-Cycle Inc
Boulder, CO. USA

-----Original Message-----
From: GreenYes@no.address [mailto:GreenYes@no.address] On Behalf
Of Doug Koplow
Sent: Tuesday, April 04, 2006 7:41 AM
To: SPENDELOW.Peter@no.address; greenyes@no.address
Subject: [GreenYes] Re: Are degradable plastics zero-waste?

I've seen some focus of these biobased products on markets for which litter
is a problem -- for example, food service near national parks. In this type
of a situation, rapid composting into water and CO2 would indeed be a

Doug Koplow
Earth Track, Inc.
2067 Massachusetts Avenue - 4th Floor
Cambridge, MA 02140
Tel: 617/661-4700
Fax: 617/354-0463

This message, and all attachments thereto, is for the designated recipient
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>>> "SPENDELOW Peter H" <SPENDELOW.Peter@no.address> 04/03/06 06:12PM

To the GreenYes list:

The GreenYes List has a lot of zero-waste advocates as members, so I thought
to an appropriate place to raise this issue.

There is a conference in Minnesota this Thursday and Friday (April 6-7) that
will look at bio-based plastics. Bio-based plastics are plastics made using
feedstocks from renewable organic molecules such as starches and sugars. A
prominent bio-based plastic is PLA (Polylactic Acid), which is formed by
fermenting sugars from corn to form lactic acid, and then polymerizing the
lactic acid into a plastic.

I have been seeing discussion from some people indicating that use of
bio-based degradable plastics is in keeping with zero waste principals,
because when you are done with the items made from PLA, you can compost them
back into carbon dioxide and water.

I am hoping to spark some discussion on whether composting PLA is really
zero waste. When I look at the web site of the Zero Waste Alliance
(, I see that their Zero Waste goal lists
"zero waste of resources" as its first goal, followed by zero waste to
landfill and zero waste of other things (hazardous waste, emissions, etc).

Composting PLA might meet the "zero waste to landfill" criteria if you don't
look at the solid wastes created in the production of the PLA, but how well
does it fare on "zero waste of resources" issue? As far as I can tell, it
fares poorly. When you compost PLA, you get nothing useful out of it - only
carbon dioxide and water. You don't get any significant amount of
"compost". Compost is valuable product for restoring organic matter to
soils, and consists mainly of complex organic molecules derived from
partially-decomposed lignins from wood and other plant matter. When you
compost leaves, grass, and wood, you get "compost". Put PLA in the compost
pile though and my understanding is that the PLA will decompose almost
completely into carbon dioxide and water, and not add anything appreciable
to the compost.

Thus, when you compost PLA, you get nothing of value out of it. All of the
work and energy that went into growing the corn, milling and isolating the
sugar and starches, fermenting them to produce lactic acid, and then
polymerizing them to form PLA - all of that is lost. All of these inputs
require fossil fuel - to produce the fertilizer, run the tractor, and do the
chemistry to produce PLA. For that matter, based on Cargill-Dow's life
cycle analysis, it currently takes almost as much fossil fuel to produce PLA
as it does to produce common commodity-grade plastics, and it takes more
fossil fuel energy that the amount of petroleum embodied in an equivalent
amount of polyethylene plastic. Cargill-Dow is working to reduce this
fossil fuel requirement, but they are not there yet.

In contrast, recycling or reusing the PLA should save considerable
resources. PLA is a thermoplastic, and it should take a lot less energy to
make a PLA item out of recycled PLA than it does to make it out of corn
sugars. Even burning PLA as a fuel should at least save the energy embodied
in the plastic itself. PLA should burn very cleanly in a large industrial

The only time I can see value in composting PLA is when PLA is used in a
manner that makes the composting of other materials easier, or where no
recycling or energy-recovery option is present. Examples include PLA bags
used for collecting food waste or yard debris for composting, or possibly
plates and utensils used in schools and institutions that compost their food

In contrast, making water bottles out of PLA and then composting those water
bottles doesn't seem very "zero waste" to me.

So - all you zero waste advocates out there - what do you think about how
degradable plastics fit in with the Zero Waste vision?

Peter Spendelow
Oregon Department of Environmental Quality

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