Bioplastics – are they the answer?

16 04 2012

From Peak Energy blog; August 27, 2008

From last week’s blog post, we discussed how bio based plastics do indeed save energy during the production of the polymers, and produce fewer greenhouse gasses during the process.  Yet right off the bat, it could be argued that carbon footprints may be an irrelevant measurement,  because it has been established that plants grow more quickly and are more drought and heat resistant in a CO2 enriched atmosphere!   Many studies have shown that worldwide food production has risen, possibly by as much as 40%, due to the increase in atmospheric CO2 levels.[1] Therefore, it is both ironic and a significant potential problem for biopolymer production if the increased CO2 emissions from human activity were rolled back, causing worldwide plant growth to decline. This in turn would greatly increase the competition for biological sources of food and fuel – with biopolymers coming in last place.[2]  But that’s probably really stretching the point.

The development of bioplastics holds the potential of renewability, biodegradation, and a path away from harmful additives. They are not, however, an automatic panacea.  Although plant-based plastics appeal to green-minded consumers thanks to their renewable origins,  their production carries environmental costs that make them less green than they may seem.  It’s important to remember that bioplastics, just like regular plastics, are synthetic polymers; it’s just that plants are being used instead of oil to obtain the carbon and hydrogen needed for polymerization.

It’s good marketing, but bad honesty, as they say, because there are so many types of plastics and bioplastics that you don’t know what you’re getting in to;  bioplastics are much more complicated than biofuels.  There are about two dozen different ways to create a bioplastic, and each one has different properties and capabilities.

Actually the term “bioplastic” is pretty meaningless, because some bioplastics are actually made from oil – they’re called “bioplastics” because they are biodegradeable.  That causes much confusion because plastics made from oil can be biodegradeable whereas some plant-based  bioplastics are not. So the term bioplastics can refer either to the raw material (biomass) or, in the case of oil-based plastic, to its biodegradability.  The problem with biodegradability and compostability is that there is no agreement as to what that actually means either,  and under what circumstances

You might also see the term “oxo-degradable”.   Oxo-degradables look like plastic, but they are not. It is true that the material falls apart, but that is because it contains metal salts which cause it to disintegrate rapidly into tiny particles. Then you cannot see it anymore, but it is still there, in the ocean too. Just as with conventional plastics, these oxo-degradables release harmful substances when they are broken down.

Let’s re-visit  some of the reasons bioplastics are supposed to be an environmental benefit:

  • Because it’s made from plants, which are organic, they’re good for the planet.  Polymer bonds can be created from oil, gas or plant materials. The use of plant materials does not imply that the resulting polymer will be organic or more environmentally friendly. You could make non-biodegradable, toxic plastic out of organic corn!
  • Bioplastics are biodegradable. Although made from materials that can biodegrade, the way that material is turned into plastic  makes it difficult (if not impossible) for the materials to naturally break down.  There are bioplastics made from vegetable matter (maize or grass, for example) which are no more biodegradable than any other plastics, says Christiaan Bolck of Food & Biobased Research.[3]  Bioplastics do not universally biodegrade in normal conditions  –  some require special, rare conditions to decompose, such as high heat composting facilities, while others may simply take decades or longer to break down again, mitigating the supposed benefits of using so-called compostable plastics material. There are no independent standards for what even constitutes “biodegradable plastic.”  Sorona makes no claim to break down in the environment; Ingeo is called “compostable” (though it can only be done in industrial high heat composters). Close studies of so-called degradable plastics have shown that some only break down to plastic particles which are so small they can’t be seen  (“out of sight, out of mind”), which are more easily ingested by animals. Indeed, small plastic fragments of this type may also be better able to attract and concentrate pollutants such as DDT and PCB.[4]
  • Bioplastics are recyclable. Because bioplastics come in dozens of varieties, there’s no way to make sure you’re getting the right chemicals in the recycling vat – so although some bioplastics are recyclable, the recycling facilities won’t separate them out.  Cargill Natureworks insists that PLA  can in theory be recycled, but in reality it is likely to be confused with polyethylene terephthalate (PET).  In October 2004, a group of recyclers and recycling advocates issued a joint call for Natureworks to stop selling PLA for bottle applications until the recycling questions were addressed.[5]  But the company claims that levels of PLA in the recycling stream are too low to be considered a contaminant.  The process of recycling bioplastics is cumbersome and expensive – they present a real problem for recyclers because they cannot be handled using conventional processes. Special equipment and facilities are often needed. Moreover, if bioplastics commingle with traditional plastics, they contaminate all of the other plastics, which forces waste management companies to reject batches of otherwise recyclable materials.
  • Bioplastics are non-toxicBecause they’re not made from toxic inputs (as are oil based plastics), bioplastics have the reputation for being non toxic.  But we’re beginning to see the same old toxic chemicals produced from a different (plant-based) source of carbon. Example:  Solvay’s bio-based PVC uses phthalates,  requires chlorine during production, and produces dioxins during manufacture, recycling and disposal. As one research group commissioned by the European Bioplastics Association was forced to admit, with regard to PVC,  “The use of bio-based ethylene is …  unlikely to reduce the environmental impact of PVC with respect to its toxicity potential.[6]

The arguments against supporting bioplastics include the fact that they are corporate owned, they compete with food, they bolster industrial agriculture and lead us deeper into genetic engineering, synthetic biology and nanotechnology.  I am not with those who think we shouldn’t go there, because we sorely need scientific inquiry  and eventually we might even get it right.  But, for example, today’s industrial agriculture is not, in my opinion, sustainable, and the genetic engineering we’re doing is market driven with no altruistic motive. 

If properly designed, biodegradable plastics have the potential to become a much-preferred alternative to conventional plastics. The Sustainable Biomaterials Collaborative (SBC)[7] is a coalition of organizations that advances the introduction and use of biobased products. They seek to replace dependence on materials made from harmful fossil fuels with a new generation of materials made from plants – but the shift they propose is more than simply a change of materials.  They promote (according to their website): sustainability standards, practical tools, and effective policies to drive and shape the emerging markets for these products.  They also refer to “sustainable bioplastics” rather than simply “bioplastics”.  In order to be a better choice, these sustainable bioplastics must be:

  • Derived from non-food, non-GMO source materials – like algae rather than GMO corn, or from sustainably grown and harvested cropland or forests;
  • Safe for the environment during use;
  • Truly compostable and biodegradable;
  • Free of toxic chemicals during the manufacturing and recycling process;
  • Manufactured without hazardous inputs and impacts (water, land and chemical use are considerations);
  • Recyclable in a cradle-to-cradle cycle.

Currently, manufacturers are not responsible for the end-life of their products. Once an item leaves their factories, it’s no longer the company’s problem. Therefore, we don’t have a system by which adopters of these new bioplastics would be responsible for recovering, composting, recycling, or doing whatever needs to be done with them after use. Regarding toxicity, the same broken and ineffective regulatory system is in charge of approving bioplastics for food use, and there is no reason to assume that these won’t raise just as many health concerns as conventional plastics have. Yet again, it will be an uphill battle to ban those that turn out to be dangerous.

A study published in Environmental Science & Technology traces the full impact of plastic production all the way back to its source for several types of plastics.[8]   Study author Amy Landis of the University of Pittsburgh says, “The main concern for us is that these plant-derived products have a green stamp on them just because they’re derived from biomass.  It’s not true that they should be considered sustainable. Just because they’re plants doesn’t mean they’re green.”

The researchers found that while making bioplastics requires less fossil fuel and has a lower impact on global warming, they have higher impacts for eutrophication, eco-toxicity and production of human carcinogens.  These impacts came largely from fertilizer use, pesticide use and conversion of lands to agricultural fields, along with processing the bio-feedstocks into plastics, the authors reported.

According to the study, polypropylene topped the team’s list as having the least life-cycle impact, while PVC and PET (polyethylene terephthalate) were ranked as having the highest life-cycle impact.

But as the Plastic Pollution Coalition tells us, it’s not so much changing the material itself that needs changing – it’s our uses of the stuff itself.  We are the problem:   If we continue to buy single-use disposable objects such as plastic bottles and plastic bags, with almost 7 billion people on the planet, our throwaway culture will continue to harm the environment, no matter what it’s made of.

The Surfrider Foundation

The Surfrider Foundation has a list of ten easy things you can do to keep plastics out of our environment:

  1. Choose to reuse when it comes to  shopping bags and bottled water.  Cloth bags and metal or glass reusable  bottles are available locally at great prices.
  2. Refuse single-serving packaging, excess  packaging, straws and other ‘disposable’ plastics.  Carry reusable utensils in your purse, backpack or car to use at bbq’s, potlucks or take-out  restaurants.
  3. Reduce everyday plastics such as sandwich bags and juice cartons by replacing them with a reusable lunch bag/box that includes a thermos.
  4. Bring your to-go mug with you to the coffee shop, smoothie shop or restaurants that let you use them. A great  way to reduce lids, plastic cups and/or plastic-lined cups.
  5. Go digital! No need for plastic cds,  dvds and jewel cases when you can buy your music and videos online.
  6. Seek out alternatives to the plastic  items that you rely on.
  7. Recycle. If you must use plastic, try to choose #1 (PETE) or #2 (HDPE), which are the most commonly recycled      plastics. Avoid plastic bags and polystyrene foam as both typically have very low recycling rates.
  8. Volunteer at a beach cleanup. Surfrider Foundation Chapters often hold cleanups monthly or more frequently.
  9. Support plastic bag bans, polystyrene  foam bans and bottle recycling bills.
  10. Spread the word. Talk to your family and friends about why it is important to Rise Above Plastics!

[1] See for example: Idso, Craig, “Estimates of Global Food Production in the year 2050”, Center for the Study of Carbon dioxide and Global Change, 2011  AND  Wittwer, Sylvan, “Rising Carbon Dioxide is Great for Plants”, Policy Review, 1992  AND  http://www.ciesin.org/docs/004-038/004-038a.html

[2] D. B. Lobell and C. B. Field, Global scale climate-crop yield relationships and the impacts of recent warming, Env. Res. Letters 2, pp. 1–7, 2007 AND L. H. Ziska and J. A. Bunce, Predicting the impact of changing CO2 on crop yields: some thoughts on food, New Phytologist 175, pp. 607–618, 2007.

[3] Sikkema, Albert, “What we Don’t Know About Bioplastics”, Resource, December 2011; http://resource.wur.nl/en/wetenschap/detail/what_we_dont_know_about_bioplastics

[4] Chandler Slavin, “Bio-based resin report!” Recyclable Packaging Blog May 19, 2010 online at http://recyclablepackaging.wordpress.com/2010/05/19/bio-based-resin-report

[6] L. Shen, “Product Overview and Market Projection of Emerging Bio- Based Plastics,” PRO-BIP 2009, Final Report, June 2009

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White biotechnology and enzymes

18 11 2011

For tens of thousands of years, humans relied on nature to provide them with everything they needed to make their lives more comfortable -cotton and wool for clothes, wood for furniture, clay and ceramic for storage containers, even plants for medicines. But this all changed during the first half of the twentieth century, when organic chemistry developed methods to create many of these products from oil.  Oil-derived synthetic polymers, colored with artificial dyes, soon replaced their precursors from the natural world.

But today, with growing concerns about the dependence on imported oil and the awareness that the world’s oil supplies are not limitless, coupled with stricter environmental regulations,  chemical and biotechnology industries are exploring nature’s richness in search of methods to replace petroleum-based synthetics.  As with other forms of biotechnology, industrial biotech involves engineering biological molecules and microbes with desirable new properties. What is different is how they are then used: to replace chemical processes with biological ones. Whether this is to produce chemicals for other processes or to create products such as biopolymers with new properties, there is a  huge effort to harness biology to accomplish what previously needed big, dirty chemical factories, but in cleaner and greener ways.

The public has for a long time perceived biotechnology to mean dangerous meddling with the genes in food and fiber crops.  But biotechnology is about much more than transgenic crops – it also uses microbes to make pharmaceuticals, for example.  Industrial biotechnology is known as “white” biotechnology, as distinct from “red” biotechnology, which is devoted to medical and pharmaceutical purposes, and “green” biotechnology, or the application of biotechnology in agriculture.

From: EuropaBio

Today, the application of biotechnology to industrial processes holds many promises for sustainable development.  One of the first goals on white biotechnology’s agenda has been the production of biodegradable plastics, and in textiles,  DuPont has invested much in the production of textile fibers from corn sugar (Sorona ®) while Cargill Dow has introduced NatureWorks ™, a polymer made from lactic acid which is used in textiles under the brand name Ingeo ®.  And these new processes have resulted in considerable environmental benefits:  In the case of Sorona ®, for example,  DuPont was able to replace the toxic elements of ethylene glycol and carbon monoxide in typical PET fibers with benign corn sugars.

But there are challenges pertaining to these new bioplastics, and the evidence that they’re actually better for the planet is hotly debated.  As Jim Thomas argues in the New Internationalist online magazine:

Strictly speaking a bioplastic is a polymer that has been produced from a plant instead of from petroleum. That is neither a new breakthrough nor a guarantee of ecological soundness. The earliest plastics such as celluloid were made from tree cellulose before petroleum proved itself a cheaper source. Today, with oil prices skyrocketing, it’s cheaper feedstock –  not green principles –  that is driving chemical companies back to bio-based plastics. Bioplastics may bring in the greenbacks for investors but are they actually green for the planet? The evidence is not convincing. For a start bioplastics may or may not be degradable or biodegradable – two terms that mean very different things. Many bio-based plastics – like DuPont’s Sorona – make no claims to break down in the environment. So much for disposal. But replacing fossil fuels with plants has to be a good idea, right? This is the premise on which the green claims of bioplastics mostly rest. Unfortunately, as advocates of biofuels have learned, switching from oil to biomass as the feedstock of our industrial economy carries its own set of problems. Like hunger.

There is nothing sustainable or organic about most industrial agriculture feedstocks. At present genetically modified corn grown using pesticides is probably the leading source of starch for bioplastics.  The link between genetic contamination and bioplastics is strong.

As concerns mount, the Sustainable Biomaterials Collaborative (SBC) – a network of 16 civil society groups and ethical businesses – is working to define a truly sustainable bioplastic. One of its founders, Tom Lent, explains that the SBC started because ‘the promise of bioplastics was not being realized’.

But biotechnology is not just about bioplastics – it’s actually mostly, these days,  about enzymes.  Biotechnology can provide an unlimited and pure source of enzymes as an alternative to the harsh chemicals traditionally used in industry for accelerating chemical reactions. Enzymes are found in naturally occurring microorganisms, such as bacteria, fungi, and yeast, all of which may or may not be genetically modified.  (We’ll come back to this important point later.)

But what are enzymes?

Enzymes are large protein molecules that  act as  catalysts – substances that start or accelerate chemical reactions without themselves being affected —  and help complex reactions occur everywhere in life.  By their mere presence, and without being consumed in the process, enzymes can speed up chemical processes – reactions occur about a million times faster than they would in the absence of an enzyme. In principle, these reactions could go on forever, but in practice most enzymes have a limited life.   There are many factors that can regulate enzyme activity, including temperature, activators, pH levels, and inhibitors.

Enzymes play a diversified role in many aspects of everyday life including aiding in digestion and the production of food as well as in industrial applications. Enzymes are nature’s catalysts. Humankind has used them for thousands of years to carry out important chemical reactions for making products such as cheese, beer, and wine. Bread and yogurt also owe their flavor and texture to a range of enzyme producing organisms that were domesticated many years ago.

Enzymes are categorized according to the compounds they act upon. Some of the most common include:

  •  proteases which break down proteins,
  •  cellulases which break down cellulose,
  •  lipases which split fats (lipids) into glycerol and fatty acids, and
  •  amylases which break down starch into simple sugars.  Human saliva, for example, contains amylase, an enzyme that helps break down starchy foods into sugars.

In textile treatment, the first enzyme applications, as early as 1857, was the use of barley for removal of starchy size from woven fabrics. The first microbial amylases were used in the 1950s for the same desizing process, which today is routinely used by the industry.

Enzymes are now widely used to prepare the fabrics that your clothing, furniture and other household items are made of.  Increasing demands to reduce pollution caused by the textile industry has fueled biotechnological advances that have replaced harsh chemicals with enzymes in many textile manufacturing processes.  The use of enzymes not only make the process less toxic (by substituting enzymatic treatments for harmful chemical treatments) and eco-friendly, they reduce costs associated with the production process, and consumption of natural resources (water, electricity, fuels), while also improving the quality of the final textile product.

But how do they work?

Rader’s Chem4Kids.com website  has a great explanation, which I’ve quoted below:

Think of enzymes as similar to keys which can open locks.  Just as when you need a key that is just the right shape to fit in a particular lock, enzymes complete very specific jobs and do nothing else.  

From: Chem4Kids

 They are very specific locks and the compounds they work with are the special keys. In the same way there are door keys, car keys, and bike-lock keys, there are enzymes for neural cells, intestinal cells, and your saliva.

Here’s the deal: there are four steps in the process of an enzyme working. 

  1.  An enzyme and a substrate are in the same area. The substrate is the biological molecule that the enzyme will attack. 
  2.  The enzyme grabs onto the substrate with a special area called the active site.  The active site is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock. 
  3. A process called catalysis happens. Catalysis is when the substrate is changed. It could be broken down or combined with another molecule to make something new. 
  4.  Then the enzyme lets go.  When the enzyme lets go, it returns to normal, ready to do another reaction. But the substrate is no longer the same – the substrate is now called the product.

Next, well take a look at how enzymes are helping to make the textile industry’s environmental footprint a bit more benign.





Biodegradeable or compostable?

1 12 2010

There is no legal definition of “biodegradable,” so the term has been used loosely by some manufacturers.  The American Society for Testing and Materials defines the term as “a degradation caused by biological activity, especially by enzymatic action, leading to a significant change in the chemical structure of the material.”

The Biodegradable Products Institute (BPI) cites a 2006 American Chemistry Council study showing that most consumers believe a product labeled “biodegradable” will go away completely and on its own in a year or less. The BPI says many consumers also believe that these products will “biodegrade” in landfills.

Because it seems a desirable product attribute, the term “biodegradable” has been applied to a wide range of products—even those that might take centuries to decompose, or those that break down into harmful environmental toxins.   Biodegradability is definitely perceived as  a positive trait, yet it could be applied to virtually anything because anything is biodegradable, given enough time.  The Federal Trade Commission (FTC) in the U.S., however, has issued some general guidelines on what types of products qualify as legitimately biodegradable, and has even sued companies for unsubstantiated, misleading and/or deceptive use of the term on product labels.

According to the FTC, only products that contain materials that “break down and decompose into elements found in nature within a reasonably short amount of time after customary disposal” should be marketed as “biodegradable.”

But the FTC acknowledges that even products appropriately labeled as biodegradable may not break down easily if they are buried under a landfill or are otherwise not exposed to sunlight, air and moisture, the key agents of biodegradation. In fact, in landfills materials degrade very, very slowly – if at all!  This is because modern landfills are designed, according to law, to keep out sunlight, air and moisture – the very ingredients needed for materials to biodegrade. This helps prevent pollutants from the garbage from getting into the air and drinking water, and slows the decomposition of the trash. In Dr. William Rathje’s book entitled “Rubbish,” he sites that “The truth is, however, that the dynamics of a modern landfill are very nearly the opposite of what most people think…Well designed and managed landfills seem to be far more apt to preserve their contents for posterity than transform them into humus or mulch. They are not vast composters: rather they are vast mummifiers.” In his book, Dr. Rathje talks about doing excavations on 15 landfills throughout North America. From those digs, they found 40 year old newspapers that were still legible, 5 year old lettuce and a 15 year old hot dog. From these studies it seems fairly clear that even organic materials take a very long time to break down in landfills let alone plastic or other items.  The reality is if any product ends up in a landfill, it will not degrade.

But the fact that a product breaks down – if it does indeed break down – may not be as important as what the product breaks down into. In a perfect would all products would break down to CO2 and H2O. But it gets more complicated as we increase the number and kinds of chemicals. The banned pesticide DDT is hazardous and toxic in its own right. And it does biodegrade, though rather slowly. The problem is that its breakdown products of DDD and DDE are even more toxic and dangerous than the original DDT.
So just because a product or ingredient is biodegradable does not mean it is healthy or safe for people or the environment – especially if it leaches harmful chemicals into the ecosystem. Under this definition, even regular oil based plastic can be advertised as “biodegradable” because at some point, sooner or later, it is going to break down into small pieces.

“Compostable”, on the other hand, has a definition that is rigorously governed by the standards ASTM D-6400, ASTM D6868, and EN13432.   The term “compostable” covers four areas:

1.      Biodegradable – i.e.,  60 – 90% of the product will break down into CO2 within 180 days in a commercial composting facility.

2.      Disintegration – this requires that 90% of the product will break down into pieces that are 2mm or smaller

3.      Eco-toxicity – the product will not deposit heavy metals that are toxic to the soil beyond that found in typical compost.

4.      Compostable products have the added implication that when they break down they turn into humus, which provides valuable nutrients to the soil.

So, while some products are considered biodegradable, they may not be considered compostable because they either don’t meet the heavy metal requirements,  don’t break down in a timely fashion or don’t contribute valuable nutrients which improves the soil.

Composting of organic waste makes sense, but compostable plastic for shopping bags, food packaging, fabric, etc. does not, because:

1.      It is up to 400% more expensive than ordinary plastic;

2.      it is thicker and heavier and requires more trucks to transport it;

3.      recycling with oil-based plastics is impossible;

4.      it uses scarce land and water resources to produce the raw material, and substantial amounts of non-renewable hydro-carbons are burned and CO2 emitted, by the tractors and other machines employed.

5.      If buried in landfill, compostable plastic can emit methane (a greenhouse gas 23 times more powerful than CO2) in anaerobic conditions.

Many industrial composters of organic waste around the world do not want plastic of any kind in their feedstock, because it is difficult to separate biodegradable plastic from ordinary plastic. Home composting of plastic is not encouraged, as it will often be contaminated with food residues, and temperatures may not rise high enough to kill the pathogens. Compostable plastic is useless in compost because 90% of it has to convert to CO2 gas in order to comply with ASTM D6400 and the other composting Standards. It therefore contributes to greenhouse gases but not to the improvement of the soil.

Meanwhile, you can follow Dave, who  buried an advertised Paper Mate  biodegradable pencil in his backyard last summer and says he will report on it’s degradation over time.  Click here to read more and follow the story!

So how does this apply to fabrics?  Well, for starters the companies that make PLA (polylactic acid) based polymers – those corn based bio plastics – advertise that their products are biodegradable.   PLA is said by the manufacturer  to decompose into carbon dioxide and water in a “controlled composting environment” in fewer than 90 days. What’s a controlled composting environment? It’s not exactly your average backyard bin, pit or tumbling barrel. It’s a large facility where compost—essentially, plant scraps being digested by microbes into fertilizer—reaches 140 degrees for ten consecutive days. So, yes, as PLA advocates say, corn plastic is “biodegradable.” But in reality very few consumers have access to the sort of composting facilities that can make that happen. NatureWorks (the largest manufacturer of PLA, owned by Cargill Dow)  has identified only  113 such facilities nationwide.

Moreover, PLA by the truckload may potentially pose a problem for some large-scale composters.  And there is no evidence that  PLA breaks down any faster than PET or other plastics in a normal landfill environment.  (Read more about PLA and biodegradability here.)

And unless the chemicals used during processing of your fabric are such that there are no chemicals which would combine with other chemicals to form molecules of anything other than water, carbon dioxide and safe organic material – then it cannot be called compostable.  If the chemicals used during processing contain, for example, heavy metals in the dyestuffs – then those metals become available to your plants in the garden – and that again knocks it out of the “compostable” set of products.  That might be o.k. if you’re growing roses rather than radishes, but if you plan to eat those plants I’d look elsewhere as a way to dispose of your fabric.  Certified fabrics  made of natural fibers which look at the chemical inputs of processing (such as GOTS and Oeko Tex) would be o.k. for use in a vegetable garden – because they have been tested to be free of toxic inputs – and they could be called “compostable”.

Resources:

The Biodegradable Products Institute, www.bpiworld.org

US Composting Council  http://www.compostingcouncil.org