Biodegradable = Plastic=20 News

Bringing the =E2=80=9CGreen News=E2=80=9D to You!

07.30.06

Turning Plastics to Biodegradable Plastic!

Posted in Green Additive Plastics at 9:05 pm by = Administrator

Bio-Batch technology = is a=20 process which enables the microorganisms in the environmentto metabolize = the=20 molecular structure of plastic films into an inert humus-like form that=20 isharmless to the environment.

Bio-Batch process = utilizes=20 several proprietary bio-active compounds that are combined into a = masterbatch=20 pellet that is easily added to plastic resins using existing technology. = The=20 biodegradation process begins with proprietary swelling agent that, when = combined with heat and moisture, expands the plastics=E2=80=99 molecular = structure.=20 After the swelling agent creates space within the plastic=E2=80=99s = molecular structure,=20 the masterbatch=E2=80=99s combination of bio-active compounds, = discovered after=20 thousands of laboratory trials, attracts a colony of microorganisms that = metabolize and neutralize the plastic.

Bio-Batch = masterbatch only=20 nominally effects production costs. This is largely because the = technology does=20 not rely on changing to re-engineered plastics which have not achieved = economies=20 of scale but merely requires adding a small percentage of a masterbatch = to=20 existing resins. In most applications, producing 100 pounds of = biodegradable=20 plastic only requires one pound of Bio-Batch.

Consequently, the = use of=20 Bio-Batch technology only increases production costs by pennies per = pound. (less=20 with orders leading to appropriate economies of scale) compared to = products made=20 wholly with traditional plastic resins.

In addition, the=20 biodegradability of Bio-Batch films does not jeopardize the = products=E2=80=99 quality.=20 Plastic products making use of the Bio-Batch technology can be = manufactured to=20 be clear, as well as opaque, and in any color.

The Company believes = that the=20 average consumer will be unable to differentiate between traditional = plastic=20 products and those produced with Bio-Batch technology on the basis of = appearance=20 and performance.

Bio-Batch Manufacturer

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Making packaging greener =E2=80=93 biodegradable = plastics

Posted in Green Resins at 8:57 pm by Administrator

This topic is sponsored by the Australian Government=E2=80=99s = National Innovation=20 Awareness Strategy. Biodegradable plastics made with plant-based = materials have=20 been available for many years. Their high cost, however, has meant they = have=20 never replaced traditional non-degradable plastics in the mass market. A = new=20 Australian venture is producing affordable biodegradable plastics that = might=20 change all that. = =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=93 Our whole world seems to be wrapped=20 in plastic. Almost every product we buy, most of the food we eat and = many of the=20 liquids we drink come encased in plastic. In Australia around 1 million = tonnes=20 of plastic materials are produced each year and a further 587,000 tonnes = are=20 imported. Packaging is the largest market for plastics, accounting for = over a=20 third of the consumption of raw plastic materials =E2=80=93 Australians = use 6 billion=20 plastic bags every year! Plastic packaging provides excellent protection = for the=20 product, it is cheap to manufacture and seems to last forever. Lasting = forever,=20 however, is proving to be a major environmental problem. Another problem = is that=20 traditional plastics are manufactured from non-renewable resources = =E2=80=93 oil, coal=20 and natural gas. Plastics that break down In an effort to overcome these = shortcomings, biochemical researchers and engineers have long been = seeking to=20 develop biodegradable plastics that are made from renewable resources, = such as=20 plants. The term biodegradable means that a substance is able to be = broken down=20 into simpler substances by the activities of living organisms, and = therefore is=20 unlikely to persist in the environment. There are many different = standards used=20 to measure biodegradability, with each country having its own. The = requirements=20 range from 90 per cent to 60 per cent decomposition of the product = within 60 to=20 180 days of being placed in a standard composting environment. The = reason=20 traditional plastics are not biodegradable is because their long polymer = molecules are too large and too tightly bonded together to be broken = apart and=20 assimilated by decomposer organisms. However, plastics based on natural = plant=20 polymers derived from wheat or corn starch have molecules that are = readily=20 attacked and broken down by microbes. Plastics can be produced from = starch=20 Starch is a natural polymer. It is a white, granular carbohydrate = produced by=20 plants during photosynthesis and it serves as the plant=E2=80=99s energy = store. Cereal=20 plants and tubers normally contain starch in large proportions. Starch = can be=20 processed directly into a bioplastic but, because it is soluble in = water,=20 articles made from starch will swell and deform when exposed to = moisture,=20 limiting its use. This problem can be overcome by modifying the starch = into a=20 different polymer. First, starch is harvested from corn, wheat or = potatoes, then=20 microorganisms transform it into lactic acid, a monomer. Finally, the = lactic=20 acid is chemically treated to cause the molecules of lactic acid to link = up into=20 long chains or polymers, which bond together to form a plastic called=20 polylactide (PLA). PLA can be used for products such as plant pots and=20 disposable nappies. It has been commercially available since 1990, and = certain=20 blends have proved successful in medical implants, sutures and drug = delivery=20 systems because of their capacity to dissolve away over time. However, = because=20 PLA is significantly more expensive than conventional plastics it has = failed to=20 win widespread consumer acceptance. Plastics can also be produced by = bacteria=20 Another way of making biodegradable polymers involves getting bacteria = to=20 produce granules of a plastic called polyhydroxyalkanoate (PHA) inside = their=20 cells. Bacteria are simply grown in culture, and the plastic is then = harvested.=20 Going one step further, scientists have taken genes from this kind of = bacteria=20 and stitched them into corn plants, which then manufacture the plastic = in their=20 own cells. What=E2=80=99s the cost? Unfortunately, as with PLA, PHA is = significantly=20 more expensive to produce and, as yet, it is not having any success in = replacing=20 the widespread use of traditional petrochemical plastics. Indeed, = biodegradable=20 plastic products currently on the market are from 2 to 10 times more = expensive=20 than traditional plastics. But environmentalists argue that the cheaper = price of=20 traditional plastics does not reflect their true cost when their full = impact is=20 considered. For example, when we buy a plastic bag we don=E2=80=99t pay = for its=20 collection and waste disposal after we use it. If we added up these = sorts of=20 associated costs, traditional plastics would cost more and biodegradable = plastics might be more competitive (Box 1: Life cycle analysis). = Biodegradable=20 and affordable If cost is a major barrier to the uptake of biodegradable = plastics, then the solution lies in investigating low-cost options to = produce=20 them. In Australia, the Cooperative Research Centre (CRC) for = International Food=20 Manufacture and Packaging Science is looking at ways of using basic = starch,=20 which is cheap to produce, in a variety of blends with other more = expensive=20 biodegradable polymers to produce a variety of flexible and rigid = plastics.=20 These are being made into =E2=80=98film=E2=80=99 and =E2=80=98injection = moulded=E2=80=99 products such as=20 plastic wrapping, shopping bags, bread bags, mulch films and plant pots. = Mulch=20 film from biodegradable plastics The CRC has developed a mulch film for = farmers.=20 Mulch films are laid over the ground around crops, to control weed = growth and=20 retain moisture. Normally, farmers use polyethylene black plastic that = is pulled=20 up after harvest and trucked away to a landfill (taking with it topsoil = humus=20 that sticks to it). However, field trials using the biodegradable mulch = film on=20 tomato and capsicum crops have shown it performs just as well as = polyethylene=20 film but can simply be ploughed into the ground after harvest. = It=E2=80=99s easier,=20 cheaper and it enriches the soil with carbon. Pots you can plant Another = biodegradable plastic product is a plant pot produced by injection = moulding.=20 Gardeners and farmers can place potted plants directly into the ground, = and=20 forget them. The pots will break down to carbon dioxide and water, = eliminating=20 double handling and recycling of conventional plastic containers. = Different=20 polymer blends for different products Depending on the application, = scientists=20 can alter polymer mixtures to enhance the properties of the final = product. For=20 example, an almost pure starch product will dissolve upon contact with = water and=20 then biodegrade rapidly. By blending quantities of other biodegradable = plastics=20 into the starch, scientists can make a waterproof product that degrades = within 4=20 weeks after it has been buried in the soil or composted. Landfill sites = aren=E2=80=99t=20 compost heaps To maximise the benefit of the new bioplastics = we=E2=80=99ll have to=20 modify the way we throw away our garbage =E2=80=93 to simply substitute = new plastics for=20 old won=E2=80=99t be saving space in our landfills. Although there is a = popular=20 misconception that biodegradable materials break down in landfill sites, = they=20 don=E2=80=99t. Rubbish deposited in landfill is compressed and sealed = under tonnes of=20 soil. This minimises oxygen and moisture, which are essential = requirements for=20 microbial decomposition. For biodegradable plastics to effectively = decompose=20 they need to be treated like compost. Composting the packaging with its = contents=20 Compost may be the key to maximising the real environmental benefit of=20 biodegradable plastics. One of the big impediments to composting our = organic=20 waste is that it is so mixed up with non-degradable plastic packaging = that it is=20 uneconomic to separate them. Consequently, the entire mixed waste-stream = ends up=20 in landfill. Organic waste makes up almost half the components of = landfill in=20 Australia. By ensuring that biodegradable plastics are used to package = all our=20 organic produce, it may well be possible in the near future to set up=20 large-scale composting lines in which packaging and the material it = contains can=20 be composted as one. The resulting compost could be channelled into = plant=20 production, which in turn might be redirected into growing the starch to = produce=20 more biodegradable plastics. An Olympic effort =E2=80=93 recycling 76 = per cent of waste=20 For anyone who thinks such schemes aren=E2=80=99t feasible, you only = have to look at the=20 recycling success of the Sydney Olympics to see that where = there=E2=80=99s a will,=20 there=E2=80=99s a way. More than 660 tonnes of waste was generated each = day at its many=20 venues. Of this, an impressive 76 per cent was collected and recycled. = Part of=20 this success was due to the use of biodegradable plastics used in the = packaging=20 of fast food, making the composting of food scraps an economic = proposition as it=20 eliminated the need for expensive separation of packaging waste prior to = processing. With intelligent use, these new plastics have the potential = to=20 reduce plastic litter, decrease the quantities of plastic waste going = into=20 landfills and increase the recycling of other organic components that = would=20 normally end up in landfills. Box 1. Life cycle analysis CREDITS

Permalink Comments=20

ADM and Metabolix Announce First Commercial Plant for PHA = Natural=20 Plastics

Posted in Uncategorized, Green Resins at 8:25 pm by Administrator

2/13/2006

Archer Daniels Midland Company (NYSE: ADM) and = Metabolix=20 have announced that ADM will build the first commercial plant to = produce a=20 new generation of high-performance natural plastics that are = eco-friendly=20 and based on sustainable, renewable resources. The plant will have = an=20 initial annual capacity of 50,000 tons per year, be located at a = major ADM=20 North American site and serve the joint venture being established = by the=20 companies.

The plant will produce PHA natural plastics = that have a=20 wide variety of applications in products currently made from = petrochemical=20 plastics, including coated paper, film, and molded goods. The PHA = natural=20 plastics are produced using a fully biological fermentation = process that=20 converts agricultural raw materials, such as corn sugar, into a = versatile=20 range of plastics that have excellent durability in use, but are=20 compostable in both hot and cold compost, and are biodegraded even = in the=20 marine environment.

=E2=80=9CThe plastics created from PHA = polymers are natural,=20 biodegradable and renewable, and we are pleased to begin their = commercial=20 production,=E2=80=9D stated G. Allen Andreas, ADM Chairman, Chief = Executive and=20 President. =E2=80=9CAs the world=E2=80=99s demand for petroleum = continues to increase, ADM=20 believes that this facility is a positive step towards producing = renewable=20 plastics that offer the global marketplace an alternative to = traditional=20 petroleum-derived plastics.=E2=80=9D

=E2=80=9CA broadly useful family of bio-based, = biodegradable=20 natural plastics will be commercially available for the first = time,=E2=80=9D=20 stated Jim Barber, President and CEO of Metabolix. = =E2=80=9CConsumers and users=20 concerned by the negative impacts of persistent petrochemical = plastics on=20 the environment and their dependence on volatile, non-renewable = resources=20 from unstable regions will now have a practical = alternative.=E2=80=9D

In 2004, ADM and Metabolix announced a = strategic=20 alliance to commercialize the Metabolix proprietary PHA = technology, which=20 is protected by over 130 issued and pending U.S. patents.

PHA natural plastics are a broad and versatile = family of=20 polymers that range in properties from rigid to elastic, and they = can be=20 converted into molded and thermoformed goods, extruded coatings = and film,=20 blown film, fibers, adhesives and many other products. They have = excellent=20 shelf life and resistance even to hot liquids, greases and oils, = yet they=20 biodegrade in aquatic, marine and soil environments and under = anaerobic=20 conditions, such as found in septic systems and municipal waste = treatment=20 plants. They can be both hot and cold composted. They are made = using=20 proprietary processes developed by Metabolix from renewable and=20 sustainable agricultural raw materials.

About Metabolix
Founded in 1992, Metabolix, = Inc. uses=20 sophisticated biotechnology to produce environmentally friendly=20 performance materials from renewable resources. Metabolix is the = world=20 leader in applying the advanced tools of metabolic engineering and = molecular biology to efficiently produce PHA biobased natural = plastics in=20 microbial systems and directly in non-food plant crops. For more=20 information, please visit www.metabolix.com.

Archer Daniels Midland Company (ADM) is a world = leader=20 in agricultural processing and fermentation technology. ADM is one = of the=20 world=E2=80=99s largest processors of soybeans, corn, wheat and = cocoa. ADM is also=20 a leader in the production of soy meal and oil, ethanol, corn = sweeteners=20 and flour. In addition, ADM produces value-added food and feed=20 ingredients. Headquartered in Decatur, Illinois, ADM has over = 25,000=20 employees, more than 250 processing plants and net sales for the = fiscal=20 year ended June 30, 2005 of $35.9 billion. Additional information = can be=20 found on ADM=E2=80=99s Web site at = http://www.admworld.com.

Permalink Co= mments=20

Is the Ban on Plastics justified?

Posted in Plastics in the Environment at 7:21 pm by=20 Administrator

Triggered by complaints of choked drainage and storm water drains due = to=20 plastic bags, the Maharashtra Government has set in motion the process = to ban=20 the use, sale and manufacture of plastic bags in the State. The ban = would be=20 applicable to all types of plastic bags and pouches, but not water = bottles. The=20 government has set a timeframe of 30 days to deal with objections and=20 suggestions from people on the issue, after which the cabinet would take = a final=20 decision. This ban is expected to come into effect on September 24, = 2005.

Click here to=20 express your feedback

Mr. A. R. Parsuraman, MD, Marigold International has shared the = following=20 thoughts with www.plastemart.com
=E2=80=9DIn the process of = =E2=80=9Cfind the guilty=E2=80=9D=20 BMC has come out with a decision of banning plastic bags across the = board. Six=20 years back they banned all carry bags under 20 micron thickness. The = attempt is=20 similar to =E2=80=9Cburning the building for eradicating the = rats=E2=80=9D. It=E2=80=99s alarming to see=20 that BMC makes the proverbial statement true. It is true that the = plastic carry=20 bags, being thrown recklessly creates nuisance value in the civic life. = Being=20 lighter it easily flies and gets into wrong places and create problems. = Being=20 lighter the littered bags do not motivate rag pickers to collect, since = it has=20 no proportionate economic value. In this whole scenario who is to be = blamed?=20 Littering is the stigma of our society. The habit of littering is the = culprit.=20 The innocent plastic bag is not to be blamed. In fact the plastic bag, = per say=20 plastics is the most eco friendly, nay, eco-saviour. Alternate packaging = materials are really not the answer. Paper, glass and metal (alternate = packaging=20 materials) are all requiring high energy levels and have direct impact = on the=20 environment. Paper packaging would result deforestation, resulting = ecological=20 imbalance and metal and glass calls for additional
power plants = (being energy=20 intensive) causing greater environmental pollution=E2=80=A6.more

Mr. Roheit of New Line Plast has the following to = say
When=20 discarded without thought, plastic bags do indeed represent one of the = most=20 visible forms of litter. In addition to the aesthetic aspects, they have = been=20 associated with harming wildlife and blocking drains. In such = circumstances one=20 can be sympathetic to the calls for bans or taxes on such products to = encourage=20 the use of more eco-friendly materials. However, the ubiquitous plastic = bag,=20 provided free by the supermarket or fast food outlet does represent a = very=20 efficient use of resources compared to most alternatives, as it serves = its=20 purpose with only a minimum=E2=80=A6.more

www.plastemart.com team has made the following observations = :
The=20 government would like us to believe that the drains will be clean after = the ban=20 on bags is imposed in Maharashtra.
Here are three pictures = =E2=80=A6more

Permalink Comments=20

How Green are Green Resins?

Posted in Green Resins at 6:56 pm by Administrator

Scientific American=20 Aug00

It is now technologically possible to make plastics = using green=20 plants rather than fossil fuels. But are these new plastics the = environmental=20 saviors researchers have hoped for? Driving=20 down a dusty gravel road in central Iowa, a farmer gazes toward the = horizon at=20 rows of tall, leafy corn plants shuddering in the breeze as far as the = eye can=20 see. The farmer smiles to himself, because he knows something about his = crop=20 that few people realize. Not only are kernels of corn growing in the = ears, but=20 granules of plastic are sprouting in the stalks and leaves.This idyllic notion of growing plastic, achievable in the = foreseeable=20 future, seems vastly more appealing than manufacturing plastic in = petrochemical=20 factories, which consume about 270 million tons of oil and gas every = year=20 worldwide. Fossil fuels provide both the power and the raw materials = that=20 transform crude oil into common plastics such as polystyrene, = polyethylene and=20 polypropylene. From milk jugs and soda bottles to clothing and car = parts, it is=20 difficult to imagine everyday life without plastics, but the = sustainability of=20 their production has increasingly been called into question. Known = global=20 reserves of oil are expected to run dry in approximately 80 years, = natural gas=20 in 70 years and coal in 700 years, but the economic impact of their = depletion=20 could hit much sooner. As the resources diminish, prices will go = up=E2=80=93a reality=20 that has not escaped the attention of policymakers. President Bill = Clinton=20 issued an executive order in August 1999 insisting that researchers work = toward=20 replacing fossil resources with plant material both as fuel and as raw=20 material.

With those concerns in mind, biochemical engineers, including the two = of us,=20 were delighted by the discovery of how to grow plastic in plants. On the = surface, this technological breakthrough seemed to be the final answer = to the=20 sustainability question, because this plant-based plastic would be = =E2=80=9Cgreen=E2=80=9D in=20 two ways: it would be made from a renewable resource, and it would = eventually=20 break down, or biodegrade, upon disposal. Other types of plastics, also = made=20 from plants, hold similar appeal. Recent research, however, has raised = doubts=20 about the utility of these approaches. For one, biodegradability has a = hidden=20 cost: the biological breakdown of plastics releases carbon dioxide and = methane,=20 heat-trapping greenhouse gases that international efforts currently aim = to=20 reduce. What is more, fossil fuels would still be needed to power the = process=20 that extracts the plastic from the plants, an energy requirement that we = discovered is much greater than anyone had thought. Successfully making = green=20 plastics depends on whether researchers can overcome these = energy-consumption=20 obstacles economically=E2=80=93and without creating additional = environmental=20 burdens.

Traditional manufacturing of plastics uses a surprisingly large = amount of=20 fossil fuel. Automobiles, trucks, jets and power plants account for more = than 90=20 percent of the output from crude-oil refineries, but plastics consume = the bulk=20 of the remainder, around 80 million tons a year in the U.S. alone. To = date, the=20 efforts of the biotechnology and agricultural industries to replace = conventional=20 plastics with plant-derived alternatives have embraced three main = approaches:=20 converting plant sugars into plastic, producing plastic inside = microorganisms,=20 and growing plastic in corn and other crops.

Cargill, an agricultural business giant, and Dow Chemical, a top = chemical=20 firm, joined forces three years ago to develop the first approach, which = turns=20 sugar from corn and other plants into a plastic called polylactide = (PLA).=20 Microorganisms transform the sugar into lactic acid, and another step = chemically=20 links the molecules of lactic acid into chains of plastic with = attributes=20 similar to polyethylene terephthalate (PET), a petrochemical plastic = used in=20 soda bottles and clothing fibers.

Looking for new products based on corn sugar was a natural extension = of=20 Cargill=E2=80=99s activities within the existing corn-wet-milling = industry, which=20 converts corn grain to products such as high-fructose corn syrup, citric = acid,=20 vegetable oil, bioethanol and animal feed. In 1999 this industry = processed=20 almost 39 million tons of corn=E2=80=93roughly 15 percent of the entire = U.S. harvest for=20 that year. Indeed, Cargill Dow earlier this year launched a $300-million = effort=20 to begin mass-producing its new plastic, NatureWorksTM PLA, by the end = of 2001=20 [see Gruber interview].

PRODUCTION AND ENERGY DEMANDS

PLANT-BASED =
PLASTICS   PHA (grown in corn plants) =
=3D 90 m/kg* of plastic

Corn stover grown, harvested and delivered to =
factory

Plastic extracted from stover using solvents

Solvents distilled and =
separated from plastic

PHA (bacterial =
fermentation) =3D 81 m/kg of plastic

Corn or other plants grown, =
harvested and delivered to factory

Plants processed to yield =
sugar

Sugar fermented into plastic inside bacteria

Bacterial cells opened; =
plastic separated, concentrated and dried

PLA =3D 56 =
m/kg of plastic  FOSSIL FUEL-BASED PLASTICS 	=

Energy*		Raw Materials* =

  =
PE	  29 		    81

PET 	  37 		 =
   76

NYLON   93 		    142

* m/kg =3D megajoules per =
kilogram of plastic

Other companies, including Imperial Chemical Industries, developed = ways to=20 produce a second plastic, called polyhydroxyalkanoate (PHA). Like PLA, = PHA is=20 made from plant sugar and is biodegradable. In the case of PHA, however, = the=20 bacterium Ralstonia eutropha converts sugar directly into plastic. PLA = requires=20 a chemical step outside the organism to synthesize the plastic, but PHA=20 naturally accumulates within the microbes as granules that can = constitute up to=20 90 percent of a single cell=E2=80=99s mass.

In response to the oil crises of the 1970s, Imperial Chemical = Industries=20 established an industrial-scale fermentation process in which = microorganisms=20 busily converted plant sugar into several tons of PHA a year. Other = companies=20 molded the plastic into commercial items such as biodegradable razors = and=20 shampoo bottles and sold them in niche markets, but this plastic turned = out to=20 cost substantially more than its fossil fuel-based counterparts and = offered no=20 performance advantages other than biodegradability. Monsanto bought the = process=20 and associated patents in 1995, but profitability remained elusive.

Many corporate and academic groups, including Monsanto, have since = channeled=20 their efforts to produce PHA into the third approach: growing the = plastic in=20 plants. Modifying the genetic makeup of an agricultural crop so that it = could=20 synthesize plastic as it grew would eliminate the fermentation process=20 altogether. Instead of growing the crop, harvesting it, processing the = plants to=20 yield sugar and fermenting the sugar to convert it to plastic, one could = produce=20 the plastic directly in the plant. Many researchers viewed this approach = as the=20 most efficient=E2=80=93and most elegant=E2=80=93solution for making = plastic from a renewable=20 resource. Numerous groups were (and still are) in hot pursuit of this = goal.

In the mid-1980s one of us (Slater) was part of a group that isolated = the=20 genes that enable the bacteria to make plastic. Investigators predicted = that=20 inserting these enzymes into a plant would drive the conversion of = acetyl=20 coenzyme A=E2=80=93a compound that forms naturally as the plant converts = sunlight into=20 energy=E2=80=93into a type of plastic. In 1992 a collaboration of = scientists at Michigan=20 State University and James Madison University first accomplished this = task. The=20 researchers genetically engineered the plant Arabidopsis thaliana to = produce a=20 brittle type of PHA. Two years later Monsanto began working to produce a = more=20 flexible PHA within a common agricultural plant: corn.

So that plastic production would not compete with food production, = the=20 researchers targeted part of the corn plant that is not typically = harvested=E2=80=93the=20 leaves and stem, together called the stover. Growing plastic in stover = would=20 still allow farmers to harvest the corn grain with a traditional = combine; they=20 could comb the fields a second time to remove the plastic-containing = stalks and=20 leaves. Unlike production of PLA and PHA made by fermentation, which=20 theoretically compete for land used to grow crops for other purposes, = growing=20 PHA in corn stover would enable both grain and plastic to be reaped from = the=20 same field. (Using plants that can grow in marginal environments, such = as=20 switchgrass, would also avoid competition between plastic production and = other=20 needs for land.)

The Problem: Energy and Emissions

Researchers have made significant technological progress toward = increasing=20 the amount of plastic in the plant and altering the composition of the = plastic=20 to give it useful properties. Although these results are encouraging = when viewed=20 individually, achieving both a useful composition and high plastic = content in=20 the plant turns out to be difficult. The chloroplasts of the leaves have = so far=20 shown themselves to be the best location for producing plastic. But the=20 chloroplast is the green organelle that captures light, and high = concentrations=20 of plastic could thus inhibit photosynthesis and reduce grain = yields.

The challenges of separating the plastic from the plant, too, are = formidable.=20 Researchers at Monsanto originally viewed the extraction facility as an = adjunct=20 to an existing corn-processing plant. But when they designed a = theoretical=20 facility, they determined that extracting and collecting the plastic = would=20 require large amounts of solvent, which would have to be recovered after = use.=20 This processing infrastructure rivaled existing petrochemical plastic = factories=20 in magnitude and exceeded the size of the original corn mill.

Given sufficient time and funding, researchers could overcome these = technical=20 obstacles. Both of us, in fact, had planned for the development of = biodegradable=20 plastics to fill the next several years of our research agendas. But a = greater=20 concern has made us question whether those solutions are worth pursuing. = When we calculated all the energy and raw materials required for = each=20 step of growing PHA in plants=E2=80=93harvesting and drying the corn = stover, extracting=20 PHA from the stover, purifying the plastic, separating and recycling the = solvent, and blending the plastic to produce a resin=E2=80=93we = discovered that this=20 approach would consume even more fossil resources than most = petrochemical=20 manufacturing routes. [emphasis added]

In our most recent study, completed this past spring, we and our = colleagues=20 found that making one kilogram of PHA from genetically modified corn = plants=20 would require about 300 percent more energy than the 29 megajoules = needed to=20 manufacture an equal amount of fossil fuel-based polyethylene (PE). To = our=20 disappointment, the benefit of using corn instead of oil as a raw = material could=20 not offset this substantially higher energy demand.

Based on current patterns of energy use in the corn-processing = industry, it=20 would take 2.65 kilograms of fossil fuel to power the production of a = single=20 kilogram of PHA. Using data collected by the Association of European = Plastics=20 Manufacturers for 36 European plastic factories, we estimated that one = kilogram=20 of polyethylene, in contrast, requires about 2.2 kilograms of oil and = natural=20 gas, nearly half of which ends up in the final product. That means only = 60=20 percent of the total=E2=80=93or 1.3 kilograms=E2=80=93is burned to = generate energy.

Given this comparison, it is impossible to argue that plastic grown = in corn=20 and extracted with energy from fossil fuels would conserve fossil = resources.=20 What is gained by substituting the renewable resource for the finite one = is lost=20 in the additional requirement for energy. In an earlier study, one of us = (Gerngross) discovered that producing a kilogram of PHA by microbial=20 fermentation requires a similar quantity=E2=80=932.39 = kilograms=E2=80=93of fossil fuel. These=20 disheartening realizations are part of the reason that Monsanto, the=20 technological leader in the area of plant-derived PHA, announced late = last year=20 that it would terminate development of these plastic-production = systems.

The only plant-based plastic that is currently being commercialized = is=20 Cargill Dow=E2=80=99s PLA. Fueling this process requires 20 to 50 = percent fewer fossil=20 resources than does making plastics from oil, but it is still = significantly more=20 energy intensive than most petrochemical processes are. Company = officials=20 anticipate eventually reducing the energy requirement. The process has = yet to=20 profit from the decades of work that have benefited the petrochemical = industry.=20 Developing alternative plant-sugar sources that require less energy to = process,=20 such as wheat and beets, is one way to attenuate the use of fossil = fuels. In the=20 meantime, scientists at Cargill Dow estimate that the first PLA = manufacturing=20 facility, now being built in Blair, Neb., will expend at most 56 = megajoules of=20 energy for every kilogram of plastic=E2=80=9350 percent more than is = needed for PET but=20 40 percent less than for nylon, another of PLA=E2=80=99s petrochemical = competitors.

The energy necessary for producing plant-derived plastics gives rise = to a=20 second, perhaps even greater, environmental concern. Fossil oil is the = primary=20 resource for conventional plastic production, but making plastic from = plants=20 depends mainly on coal and natural gas, which are used to power the = corn-farming=20 and corn-processing industries. Any of the plant-based methods, = therefore,=20 involve switching from a less abundant fuel (oil) to a more abundant one = (coal).=20 Some experts argue that this switch is a step toward sustainability. = Missing in=20 this logic, however, is the fact that all fossil fuels used to make = plastics=20 from renewable raw materials (corn) must be burned to generate energy, = whereas=20 the petrochemical processes incorporate a significant portion of the = fossil=20 resource into the final product.

Burning more fossil fuels exacerbates an established global climate = problem=20 by increasing emissions of greenhouse gases, such as carbon dioxide [see = =E2=80=9CIs=20 Global Warming Harmful to Health?=E2=80=9D by Paul R. Epstein]. = Naturally, other=20 emissions associated with fossil energy, such as sulfur dioxide, are = also likely=20 to increase. This gas contributes to acid rain and should be viewed with = concern. What is more, any manufacturing process that increases such = emissions=20 stands in direct opposition to the Kyoto Protocol, an international = effort led=20 by the United Nations to improve air quality and curtail global warming = by=20 reducing carbon dioxide and other gases in the atmosphere.

The conclusions from our analyses were inescapable. The environmental = benefit=20 of growing plastic in plants is overshadowed by unjustifiable increases = in=20 energy consumption and gas emissions. PLA seems to be the only = plant-based=20 plastic that has a chance of becoming competitive in this regard. Though = perhaps=20 not as elegant a solution as making PHA in plants, it takes advantage of = major=20 factors contributing to an efficient process: low energy requirements = and high=20 conversion yields (almost 80 percent of each kilogram of plant sugar = used ends=20 up in the final plastic product). But despite the advantages of PLA over = other=20 plant-based plastics, its production will inevitably emit more = greenhouse gases=20 than do many of its petrochemical counterparts.

Green-PlasticsAug00.htm

As sobering as our initial analyses were, we did not immediately = assume that=20 these plant-based technologies were doomed forever. We imagined that = burning=20 plant material, or biomass, could offset the additional energy = requirement.=20 Emissions generated in this way can be viewed more favorably than the = carbon=20 dioxide released by burning fossil carbon, which has been trapped = underground=20 for millions of years. Burning the carbon contained in corn stalks and = other=20 plants would not increase net carbon dioxide in the atmosphere, because = new=20 plants growing the following spring would, in theory, absorb an equal = amount of=20 the gas. (For the same reason, plant-based plastics do not increase = carbon=20 dioxide levels when they are incinerated after use.)

We and other researchers reasoned that using renewable biomass as a = primary=20 energy source in the corn-processing industry would uncouple the = production of=20 plastics from fossil resources, but such a shift would require hurdling = some=20 lingering technological barriers and building an entirely new = power-generation=20 infrastructure. Our next question was, =E2=80=9CWill that ever = happen?=E2=80=9D Indeed,=20 energy-production patterns in corn-farming states show the exact = opposite trend.=20 Most of these states drew a disproportionate amount of their electrical = energy=20 from coal=E2=80=9386 percent in Iowa, for example, and 98 percent in = Indiana=E2=80=93compared=20 with a national average of around 56 percent in 1998. (Other states = derive more=20 of their energy from sources such as natural gas, oil and hydroelectric=20 generators.)

Both Monsanto and Cargill Dow have been looking at strategies for = deriving=20 energy from biomass. In its theoretical analysis, Monsanto burned all = the corn=20 stover that remained after extraction of the plastic to generate = electricity and=20 steam. In this scenario, biomass-derived electricity was more than = sufficient to=20 power PHA extraction. The excess energy could be exported from the=20 PHA-extraction facility to replace some of the fossil fuel burned at a = nearby=20 electric power facility, thus reducing overall greenhouse gas emissions = while=20 producing a valuable plastic.

Interestingly, it was switching to a plant-based energy = source=E2=80=93not using=20 plants as a raw material=E2=80=93that generated the primary = environmental benefit. Once=20 we considered the production of plastics and the production of energy=20 separately, we saw that a rational scheme would dictate the use of = renewable=20 energy over fossil energy for many industrial processes, regardless of = the=20 approach to making plastics. In other words, why worry about supplying = energy to=20 a process that inherently requires more energy when we have the option = of making=20 conventional plastics with much less energy and therefore fewer = greenhouse gas=20 emissions? It appears that both emissions and the depletion of fossil = resources=20 would be abated by continuing to make plastics from oil while = substituting=20 renewable biomass as the fuel.

Unfortunately, no single strategy can overcome all the environmental, = technical and economic limitations of the various manufacturing = approaches.=20 Conventional plastics require fossil fuels as a raw material; PLA and = PHA do=20 not. Conventional plastics provide a broader range of material = properties than=20 PLA and PHA, but they are not biodegradable. Biodegradability helps to = relieve=20 the problem of solid-waste disposal, but degradation gives off = greenhouse gases,=20 thereby compromising air quality. Plant-based PLA and PHA by = fermentation are=20 technologically simpler to produce than PHA grown in corn, but they = compete with=20 other needs for agricultural land. And although PLA production uses = fewer fossil=20 resources than its petrochemical counterparts, it still requires more = energy and=20 thus emits more greenhouse gases during manufacture.

The choices that we as a society will make ultimately depend on how = we=20 prioritize the depletion of fossil resources, emissions of greenhouse = gases,=20 land use, solid-waste disposal and profitability=E2=80=93all of which = are subject to=20 their own interpretation, political constituencies and value systems. = Regardless=20 of the particular approach to making plastics, energy use and the = resulting=20 emissions constitute the most significant impact on the environment.

In light of this fact, we propose that any scheme to produce plastics = should=20 not only reduce greenhouse gas emissions but should also go a step = beyond that,=20 to reverse the flux of carbon into the atmosphere. To accomplish this = goal will=20 require finding ways to produce nondegradable plastic from resources = that absorb=20 carbon dioxide from the atmosphere, such as plants. The plastic could = then be=20 buried after use, which would sequester the carbon in the ground instead = of=20 returning it to the atmosphere. Some biodegradable plastics may also end = up=20 sequestering carbon, because landfills, where many plastic products end = up,=20 typically do not have the proper conditions to initiate rapid = degradation.

In the end, reducing atmospheric levels of carbon dioxide may be too = much to=20 ask of the plastics industry. But any manufacturing process, not just = those for=20 plastics, would benefit from the use of renewable raw materials and = renewable=20 energy. The significant changes that would be required of the = world=E2=80=99s electrical=20 power infrastructure to make this shift might well be worth the effort. = After=20 all, renewable energy is the essential ingredient in any comprehensive = scheme=20 for building a sustainable economy, and as such, it remains the primary = barrier=20 to producing truly =E2=80=9Cgreen=E2=80=9D plastics.

Further Information:

Polyhydroxybutyrate, a Biodegradable Thermoplastic, Produced in = Transgenic=20 Plants. Y. Poirier, D. E. Dennis, K. Klomparins and C. Somerville in = Science,=20 Vol. 256, pages 520-622; April 1992.

Can Biotechnology Move Us toward a Sustainable Society? Tillman U. = Gerngross=20 in Nature Biotechnology, Vol. 17, pages 541-544; June 1999.

Author: http://engineering.dartmouth.edu/thayer/faculty/tillmangerngross.ht= ml

The Author
TILLMAN U. GERNGROSS and STEVEN C. SLATER have each = worked for=20 more than eight years in industry and academia to develop technologies = for=20 making biodegradable plastics. Both researchers have contributed to=20 understanding the enzymology and genetics of plastic-producing bacteria. = In the=20 past two years, they have turned their interests toward the broader = issue of how=20 plastics manufacturing affects the environment. Gerngross is an = assistant=20 professor at Dartmouth College, and Slater is a senior researcher at = Cereon=20 Genomics, a subsidiary of Monsanto, in Cambridge, Mass.

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