Bioplastics’ Contribution to Plastic Pollution

Since bioplastics still comprise only an extremely small part
of the plastics market (less than 1 percent, remember?), I think
the most important question to ask is: do we really want that
value to grow? And if it does, can it do so in a manner that
makes sense from an environmental perspective? I know it
may seem like bioplastics are ideal for sustainability, but the
reality of the situation is that they aren’t a cure-all for our
plastic problem.

Have you ever heard the term “greenwashing”? Greenwashing
is a form of spin in which marketing is deceptively
used to make a company, policy, or product look environmentally
friendly, when in reality it’s anything but. Whether it is
to increase profits or gain political backing, greenwashing’s
goal is to manipulate popular opinion to garner support for
things or sell products that really aren’t so green at all. I employ
the term “greenwashing” here because both biofuels and
bioplastics rely on it to a degree. Their marketing campaigns
tend to boil a very complex issue down to a somewhat deceptive
brand logo, like an image of a happy green cornstalk
under puffy white clouds. I urge you to think back to the
discussion of life cycle assessments and remember
to always consider the whole picture (or life cycle) when
presented with seemingly green ideas, products, or politics.
With bioplastics, it’s easy to leave out a large portion of
the life cycle and come to some very erroneous conclusions
regarding the costs. Often omitted is the amount of energy
that goes into, and the negative effects related to, the growing,
harvesting, and transportation of bioplastics. Also, in a
world full of hungry people, do we really want to be pushing
agricultural lands into production of plastics rather than
food?

I’m not saying that bioplastics are all bad—they aren’t.
But realizing their shortcomings is critical to making informed
decisions as consumers and citizens. To add another
layer of complexity, just as with regular plastics, there are
several types of bioplastics, each with their own characteristics
to consider.

When I hear the term “bioplastics,” I think it’s some snazzy
new invention, but these have actually been around for a really
long time. Henry Ford even used corn-based plastics in
the construction of the Model T in the early 1900s.
In modern society there are two popular types of bioplastic:
polylactic acid (PLA) and polyhydroxyalkanoate (PHA).
Both PLA and PHA cost more than traditional plastics to
produce. This is one of the greatest barriers to bioplastics expansion.
For now, PLA costs about 20 percent more and
PHA is nearly double the price of traditional petroleum-based
plastics, but this could change. PLA and PHA are made using
starches and sugars (e.g., cornstarch) and both degrade
easily, or at least there are claims that both degrade easily.
However, PHA can handle higher temperatures than PLA,
making it more durable in a sense. Yet Metabolix, the primary
manufacturer of PHA, claims that PHA is so biodegradable it
will break down in streams and seawater without even being
composted!

The issues surrounding the sustainability of bioplastics
are, not surprisingly, quite complex. A particularly fascinating
concern regarding bioplastics is of a behavioral nature. Steve
Davies, the marketing director for NatureWorks, raises an
interesting point about consumer behavior with regard to
items like bioplastic bottles when he says, “They’ll think, ‘Oh,
I can flip it out the car window and it will disappear on the
side of the road,’ and it absolutely won’t.” Even in the instances
where people do pay attention and place bioplastic items in the
recycling bin, they usually wind up in the landfill anyway.
Bioplastics get rejected from the recycling stream because
the majority of recycling centers in the United States are still
unprepared to handle them. Which means one of two things:
either the bioplastic item ends up in a batch of regular recycling, where it becomes a contaminant, or it gets tossed into a landfill.

When bioplastics get tossed into a landfill they decompose
in an anaerobic environment to form methane (CH4), a
green house gas twenty-one times more effective at trapping
heat than carbon dioxide. So you can see how that might not
be a great thing. However, landfills can be equipped with the
ability to capture methane and create energy to power all
sorts of things. Many landfills in the United States are already
equipped with this very technology. We actually excel
in this department: “nearly 60 percent of the worldwide capture
of methane occurs in the United States even though the
US only generates 24 percent of the worldwide methane,”
according to a report on The Importance of Landfill Gas Capture
and Usage in the U.S. by the Council for Sustainable Use
of Resources at the Columbia Earth Engineering Center. The
potential for this technology to mitigate green house gas
emissions and to generate power is quite astounding. The Intergovernmental
Panel on Climate Change estimates “gas
collection and utilization could reduce methane emissions
from landfills globally by 70 percent at negative to low costs
by 2030.” The report by Columbia concludes using methane
generated by landfills is a “win/win opportunity,” the reason
being that using the methane created in landfills to create
energy converts that methane back to carbon dioxide, which
is the very same gas that would have been created if the waste
didn’t end up in the landfill in the first place. And you can
still obtain the primary energy benefit of the methane at the
same time.

All this talk of landfills isn’t to say that bioplastics are inherently
unrecyclable, because they aren’t. PLA is actually
highly recyclable and can be recycled over and over again. But
it cannot be mixed with the traditional plastic recycling
stream. Therefore, a good method for separating bioplastics
from petroleum-based plastics is needed. Germany, Switzerland,
and Sweden require manufacturers to prominently mark
products that are compostable so they can be identified and
separated. The best separation method is infrared scanning,
which can be used to differentiate between plastic types; unfortunately,
this is an expensive technology that is out of reach
for many of the small recycling facilities in the United States.
Others have suggested a uniform color designation for compostable
plastic products would help people to sort them.

Bioplastics don’t necessarily free us from the concerns of
endocrine disruptors either. For example, Europe an Bioplastics
states “its members are committed to avoiding the use of
harmful substances in their products. Many plastic products
do not use any plasticisers and a range of acceptable plasticisers
is available if necessary. The wide range of bioplastics is
based on thousands of different formulas. This means specific
information regarding a certain material or product can only
be obtained from the individual manufacturer, converter or
brand owner using the material.” So there is no uniform answer.
They may have endocrine disruptors, they may not. Best
to just avoid plastic all together.

Understanding the other potential downfalls associated
with bioplastics should also inform your decisions.

A paper in Environmental Science & Technology, a well-regarded
peer-reviewed journal, conducted life cycle analyses
of several bioplastics versus traditional non-bioplastics and
found some rather interesting results. The study rated the
different plastics on a number of categories ranging from
human health concerns, like potential to cause cancer, to
environmental health effects, like global warming and eutrophication
(the overloading of nutrients to waterways).
This study used a “cradle to gate” assessment, meaning that
it included the production of the plastics but not their use or
disposal. In the case of assessing bioplastics, disposal may
obviously have some benefits relative to traditional plastics.
That is to say, what’s the benefit of a plastic that composts
rather than persists? Leaving out disposal seems kind of
stupid, I know, but there is a good reason for this, which is
that there is little quantitative information on the emissions
and energy from degradation of bioplastics on which to base
an LCA.

The assessment’s results are a little bit surprising in that
the bioplastics came out looking far less green than you might
expect. The LCA conducted by Environmental Science &
Technology found that bioplastics ranked most poorly in five of
the ten categories assessed in this study, including ozone depletion,
acidification, eutrophication, carcinogens, and ecotoxicity.
That means that bioplastics, when assessed on a “cradle
to gate” scale, may not always be so great, especially relative to
more simple traditional plastics. The production of HDPE,
LDPE, and PP did not result in the maximum impact in any
category, likely because these are simple polymers that require
less chemical processing than others. The authors make the
point that “adhering to green design principles reduces environmental
impact in either the petroleum or biological
polymer categories. Switching from petroleum feedstocks to
biofeedstocks does not necessarily reduce environmental impacts.”
The article also steps back and makes the recommendation
that limiting bioplastics to those made from renewable
resources that require little pesticide use or fertilizer might be
an excellent thing for further mitigating the negative impacts
bioplastic production. Harvesting invasive plants for such purposes
comes to mind. I like the idea of cleaning up problems
and producing plastics at the same time.

Bioplastics: The Solution to All Our Plastic Problems?

1. Right now bioplastics account for less than 1 percent of
plastics.

2. Bioplastics aren’t necessarily greener. Producing them
may require more energy, cause more pollution, and detract
from lands available for food production in a world
with a lot of hungry people.

3. Advances and innovation in the production of bioplastics
does make them promising. PHA plastics are produced
by microbes and there are companies that claim
to be producing carbon negative plastics without utilizing
valuable cropland.

Reprinted with permission from Plastic Purge by Michael SanClements and published by St. Martin’s Press, 2014. Buy this book from our store: Plastic Purge.