Bioplastics: an important component of global sustainability

(This work was commissioned by Biome Bioplastics, a leading European bioplastics company. A formatted version of the paper is available on the company website -www.biomebioplastics.com)

Plastics are a vital asset for humanity, often providing functionality that cannot be easily or economically replaced by other materials. Most plastics are robust and last for hundreds of years. They have replaced metals in the components of most manufactured goods, including for such products as computers, car parts and refrigerators, and in so doing have often made the products cheaper, lighter, safer, stronger and easier to recycle.[1] Plastics have taken over from paper, glass and cardboard in packaging, usually reducing cost and carbon emissions while also providing better care of the items that they protect.[2][3]

But we all know about the counterbalancing disadvantages.

  • Plastic litter disfigures the oceans and the coastlines. Ingestion of plastic kills marine creatures and fish. Perhaps 5% of the world’s cumulative output of plastic since 1945 has ended up in the oceans. Shopping bags and other packaging are strewn across the streets and fields of every country in the world.
  • Plastics use valuable resources of oil
  • The plastics industry uses large amounts of energy, usually from fossil fuel sources which therefore adds to the world’s production of greenhouse gases.
  • The durability of plastics means that without effective and ubiquitous recycling we will see continuing pressure on landfill. Although plastics do not represent the largest category of materials entering landfill – a position held by construction waste – they are a highly visible contributor to the problems of waste disposal.
  • The manufacturing of conventional plastics uses substantial amounts of toxic chemicals.
  • Some plastics leach small amounts of pollutants, including endocrine disruptors, into the environment. These chemicals can have severe effects on animals and humans. (The solution to this problem is to avoid using original raw materials - either monomers or plasticizers -that might produce such compounds when the plastic is in use or has been discarded).

The world needs to find a solution that gives us continued access to plastics but avoids these serious problems.  Bioplastics - partly or wholly made from biological materials and not crude oil - represent an effective way of keeping the huge advantages of conventional plastics but mitigating their disadvantages.

What is a bioplastic?                                                                                                                                              

A bioplastic is a plastic that is made partly or wholly from polymers derived from biological sources such as sugar cane, potato starch or the cellulose from trees, straw and cotton. Some bioplastics degrade in the open air, others are made so that they compost in an industrial composting plant, aided by fungi, bacteria and enzymes. Others mimic the robustness and durability of conventional plastics such as polyethylene or PET. Bioplastics can generally be directly substituted for their oil-based equivalent. Indeed, they can generally be made to be chemically identical to the standard industrial plastics.

In thinking about the potential role of bioplastics, we need to distinguish between two different types of use.

  • Items that might eventually become litter – such as shopping bags or food packaging – can be manufactured as bioplastics to degrade either in industrial composting units or in the open air or in water. Strenuous efforts need to be made to continue to reduce the amount plastic employed for single use applications. But if the world wishes to continue using light plastic films for storage, packaging or for carrying goods, then the only way we can avoid serious litter problems is to employ fully biodegradable compounds.[4]
  • Permanent bioplastics, such as polythene manufactured from sugar cane, can provide a near-perfect substitute for oil-based equivalents in products where durability and robustness is vital. Plastics made from biological materials generally need far smaller amounts of energy to manufacture but are equally recyclable. They use fewer pollutants during the manufacturing process. Per tonne of finished products, the global warming impact of the manufacture of bioplastics is less, and often very substantially less, than conventional plastics.

Plastics are regarded with deep ambivalence in the much of the world. Their association with indestructible and unsightly litter sometimes blinds us to their enormous value. Bioplastics – with a low carbon footprint and the capability of being made to completely degrade back to carbon dioxide and water – are a vital and growing complement to conventional oil-based plastics. They can be made to completely avoid the use of the monomers and additives that may have effects on human or animal health. As oil becomes scarcer, the value of bioplastics will increase yet further.

Plastics

About 4% of the world’s oil production is converted into plastics for use in products as varied as shopping bags and the external panels of cars. Another few percent is used in processing industries because oil-based plastics require substantial amounts of energy to manufacture. Each kilogramme of plastic typically requires 20 kilowatt hours of energy in the manufacturing process, more than the amount needed to make steel of the same weight. Almost all this comes from fossil sources. One survey suggested that the plastics industry was responsible for about 1.5% of allUSenergy consumption.

As oil runs out, and the use of fossil fuels becomes increasingly expensive, the need for replacement sources of raw material for the manufacture of vital plastics becomes increasingly urgent.  In addition, the use of carbon-based sources of energy for use in plastics manufacturing adds greenhouse gases to the atmosphere, impeding the world’s attempts to cut CO2 emissions.

These problems can be overcome. All the major oil-based plastics have substitutes made from biological materials. The polyethylene in a shopping bag can be made from sugar cane and the polypropylene of food packaging can be derived from potato starch. Plastics are irreplaceable and will all eventually be made from agricultural materials.

The world plastics industry and the role of bioplastics.                                                                             

The annual output of the world’s plastics industry is about 225 million tonnes a year.[5] This number has grown by a few per cent per year over the last decade. The bioplastics industry is much smaller, with 2011 probably seeing a total output of about 1m tonnes, or less than half of one per cent of total world plastics output. But the growth rate of bioplastics is much higher. Most sources suggest that this part of the plastics industry is growing at least 20% a year. The reasons for this buoyancy are discussed later in this note.

Not even the most fervent advocates of the bioplastics suggest that they will quickly replace all oil-derived compounds though most people expect rapid growth to continue.

  • They are generally two or three times more expensive than the major conventional plastics such as polyethylene or PET. This disadvantage will tend to diminish as bioplastics manufacturing plants become larger and benefit from economies of scale. When the local biological feedstock is particularly cheap, as it is in Brazil, large bio-polyethylene plants may already be close to being cost-competitive with oil-based alternatives.[6] But more generally, the crude oil for a kilo of plastic costs around €0.20 but the corn, a key source of feedstocks for bioplastics currently (August 2011) costs about twice this amount.
  • Their physical characteristics are not always a perfect substitute for the equivalent polymer. Sometimes the differences are trivial, such as the biological version having a slightly different texture, but in some cases the bioplastic cannot substitute for the conventional plastic. But for the most important plastic – polythene – the product based on biological sources is identical to the plastic made from oil.
  • There are a huge number of different market segments in which bioplastics can compete. In some cases, bioplastics are likely to make substantial inroads into share of traditional plastics while in others they will struggle. Novamont, the leading Italian bioplastics company, has estimated that biodegradable plastics can replace about 45% of the total sales of oil-based plastics in horticulture and 25% of those used in catering. Others regard these estimates as too low.
  • The Committee of Agricultural Organisations in the European Union suggested a figure for the accessible market for bioplastics in the EU alone at around 2m tonnes, several times the current production level. It sees the most important single segment as catering products, such as single use cutlery, followed by vegetable packaging.

Bioplastics versus food

In many types of applications, bioplastics offer substantial advantages over conventional products. Nevertheless, despite their relatively minor current role, one serious issue does need to be addressed, both now and in the future.

At the moment many bioplastics are made from sugars and starches harvested from crops that otherwise might be grown for food. As with liquid biofuels, the bioplastics industry has to deal with the vitally important question of whether the growth of bioplastics will tend to decrease the land available for food production, or increase the incentive to cut down forested areas to create more arable land. Cutting down forests is bad for global warming - because it returns carbon to the atmosphere - and bad for the wider environment because it tends to decrease biodiversity and increase erosion and flooding.

At present, the world bioplastics industry produces about 1 million tonnes of material. Perhaps 300,000 hectares are used to grow the crops which the industry processes into plastics.[7] For comparison, this is about 0.02% of the world’s total naturally irrigated area available for cultivation.[8]  Even if half the world’s plastics were made from crops grown on food land, the industry would only require 3% of the world’s cultivated acreage. By contrast, the bioethanol industry in the US uses over one tenth of the country’s arable acres to grow corn, but this fuel provides less than 10% of total liquid transport fuel. Biofuels are already an order of magnitude more important than bioplastics will ever be in using the world’s productive land.

How important is this issue?                            

The impact of the growth of bioplastics on the land available for growing food and on maintaining forest cover is an issue that needs to be openly discussed, as it is with the use of foodstuffs as feedstocks for biofuel refineries. But the world’s plastic industry is only about one tenth the size of the transport fuels sector in terms of its use of oil. If today’s entire plastics production was made from biological sources it would consume between 0.1% and 0.2% of the globe’s total annual production of organic matter (‘net primary production’). This is not a trivial amount but concerns about the competition for land need to be balanced by consideration of the enormous potential value of making bioplastics compared to the equivalent oil-based plastics.

In fact, the position is even less threatening. First, bioplastics are often made from products that would otherwise be wasted because they are unusable for human consumption. Potato starch is a by-product of some food production processes. As well as for bioplastics, this product – a waste that would otherwise have to be disposed of – is used for products as diverse as a constituent of drilling mud for oil and gas exploration and as a wallpaper paste. Plastics applications are only ever likely to be a small portion of total demand for this source of biological starch.

Sugar cane for bioplastics is usually grown on land in Brazil that has few alternative uses and certainly could not be used to grow grains. Furthermore the energy used to power the manufacturing process that creates the bioplastic from sugar is provided by the combustion of the stalks and leaves (‘bagasse’) of the cane, and no fossil fuel is used. Sugar cane is also the primary source of Brazil’s bioethanol which provides much of the country’s transport fuel. The crop is grown on dry lands, often used previously for cattle pasture but now so degraded that it cannot be used for any other form of intensive agriculture. There is no risk of sugar plantations encroaching on the precious Amazonian rain forest, which is over two thousand kilometres away from the land used for growing sugar cane. Braskem, the Brazilian company that is the largest plastics producer in the Americas, has just established a 200,000 tonne biopolyethylene plant (equivalent to about 20% of the world’s current bioplastics production) and states that growing the feedstock for this factory will use less than 0.1% of all Brazilian arable land.

Furthermore, as technology improves industry participants will have a much wider variety of raw material sources to use to make bioplastics. It will eventually be unnecessary to use land that might otherwise have been used for food. The list of potential alternative feedstuffs includes algae, which grows in water rather than on land, and cellulose. The cellulose molecule, which is the most abundant carbon-containing molecule in the natural world, forms the bulk of the weight of trees and of agricultural wastes such as straw. It was also the basis of the first commercial plastic, Parkesine, which was patented in 1856, and other historically important plastics such as celluloid. As oil becomes scarcer and more expensive the move back to cellulose and other biological feedstocks will represent a return to the days before the abundant availability of cheap petrochemicals.

Biome Bioplastics has traditionally focused on using potato starch as the main feedstock for its products. But as an illustration of the trend towards new feedstocks, nine out of the twelve new products launched this year have used non-starch polymers. The research and development needs to continue in the laboratories of bioplastics companies around the world.

As Dr Anne Roulin, the global head of packaging and design at Nestle, says when referring to the need to develop cellulose and other bioplastic polymers, ‘I think it is going to be an evolution where we will continuously reduce environmental impact and find more energy efficient processes. But I really see the trend going in the direction of conventional plastics made from renewable resources’.[9]

Finally, we need to consider the impact of improved recycling. Until a few years ago, the amount of plastic recycled was tiny. The costs of separating and cleaning different types of plastic were too high. Advances in recognition technology  - usually using infra-red or ultra-violet sensors to identify each of the key types of plastic – are enabling recyclers like Lincolnshire-based Eco Plastics to sort, clean and then resell almost all types of plastic. Their Hemswell plant has a total capacity equivalent to almost 5% of the UK’s total plastic consumption and enabling Coca Cola, for example, to source an increasing fraction of its total need for plastic from recycled PET, whether initially made from oil or from starch.[10]

About 25% of the UK’s plastic is now recycled and this can continue to rise strongly in the next few years, with the only obstacle being a shortage of state-of-the-art facilities like Hemswell. Why are we stressing the importance of the recycling of non-biodegradable plastics, whether from oil or from plant matter? Because the world needs to be more economical in its use of its scarce resources. Whether this is the oil used for most plastics or the starches, sugars and cellulose for biological plastics, we cannot afford to continue to throw away three quarters of the plastic we use. A swing towards biologically-sources plastics should not mean any let up in the move towards near-100% recycling of all types of plastics, whether made from oil or from agricultural wastes.

The benefits from using bioplastics

a)      Major consumer goods brands and bioplastics

Over the last five years many of the world’s largest consumer good companies have begun to employ bioplastics in the packaging of their products. Examples include Coca Cola’s use of a mixture of a conventional plastic and bioplastic in its soft drink bottles, Proctor and Gamble’s bioplastic shampoo packaging and Nestle’s adoption of a bioplastic top for his Brazilian milk products.

Coca Cola’s PlantBottle uses petroleum PET and up to 30% plant-based equivalent. The bottle can be reprocessed through existing recycling facilities in exactly the same way as other PET bottles. Coca Cola aims at using bottles that are ‘made with 100 per cent plant-waste material while remaining completely recyclable’, according to Scott Vitters, director of sustainable packaging at the company.

Coca Cola recognises the danger of raw material production for bioplastics diverting farmland away from the production of food or resulting in the loss of woodland. But the newsletter Business Green reported comments from Dr Jason Clay, senior vice president of market transformation for the WWF, saying that Coca-Cola had taken precautionary measures to ensure its bio-plastic does not inadvertently lead to deforestation and increased emissions.

‘Coca-Cola is currently sourcing raw materials for its PlantBottle from suppliers in Brazil, where third parties have verified that best-in-class agricultural practices are the norm," he said. ‘Preserving natural resources through sustainable agriculture is essential for businesses like Coca-Cola as they search for ways to alleviate environmental challenges.’[11]

Jason Clay of WWF also has warm words for Proctor and Gamble’s new polyethylene biopackaging, also made from sugar cane sourced from Brazil. ‘P&G's commitment to use renewable bio-derived plastic in its global beauty and grooming product packaging is an important step forward in its efforts to improve the environmental profile of its products,’ he said.[12]

Nestle is also moving rapidly towards the increased use of bioplastics, saying publicly in July 2011 that it ‘is involved in over 30 projects to introduce bioplastics in its product packaging portfolio worldwide.’[13]  In early 2011, the company launched packaging made from renewable resources for its pet food packaging in the US.

The introduction of renewable and recyclable packaging hasn’t been problem free everywhere. SunChips, a subsidiary of PepsiCo’s Frito-Lay snacks unit, recently stopped using an early version of a compostable packaging film for most of its products. The plastic film made from PLA – a renewable plastic made from corn starch – was regarded as ‘too noisy’ by customers. But SunChips didn’t lose its commitment to compostable plastic packaging. Instead its web site says that ‘we’ve created a new, quieter fully compostable chip bag that’s easy on the ears. Our new quieter compostable plastic bag will be rolling out over the next month’.[14] (We believe that the new packaging is still made from PLA) On the parent company’s web site, the statements continue to stress the importance of renewable plastic films.  ‘There’s enormous opportunity to reduce our use of non-renewable resources by using plant-based materials,’ says Tony Knoerzer, Frito-Lay’s Director of Sustainable Packaging.[15]

These four companies are among the biggest consumer goods companies in the world, with operations in almost every country. All of them appear to be committed to an increase in the use of bioplastic packaging for their products. Their reasons are simple: these businesses are watching the actions and attitudes of their customers who are increasingly concerned about the use of fossil fuel resources and, particularly, about indestructible litter. Bioplastics are important in helping consumer goods companies present their brands in a favourable light. Recyclable or compostable packaging made from biological materials can be used to make their products more environmentally friendly in the eyes of consumers. Although bioplastics may be more expensive per kilo of packaging, the extra cost is more than outweighed by the benefits seen by purchasers. The client lists of the major bioplastic suppliers include most of the largest and best-known consumer goods companies, ranging from the Shiseido cosmetics brand to Ecover, the Belgian cleaning products company.

In addition, large companies like these are becoming more aware of the risk of disruption to the supply of oil-based plastics. In order to ensure that at least part of the operations could continue after a loss of availability of conventional plastics - perhaps because of an oil embargo – many large and responsible companies are investing now in developing bioplastic packaging.

b)      The value of the reduction in landfill/expensive preparation for recycling

Some bioplastics are as robust and durable as their oil-based equivalents. Others will rapidly break down in commercial composting plants. These rapidly biodegradable plastics have high value in some circumstances such as when plastics become inevitably mixed with other streams of compostable waste and would otherwise need to be hand separated. For example, quantities of plastic material are used in greenhouse applications. A productive application for bioplastics is the ties that hold tomato vines to the support wires in commercial greenhouses. After the crop is concluded, the waste organic material, including the ties and other plant-based plastics such as the small pots in which plants are grown as seedlings, can be quickly and efficiently cleared and taken to be composted. Conventional plastics would have to be separated by hand at great expense and usually then sent to an incinerator or landfill.

A more substantial application also arises in the horticultural sector. Many field grown vegetables are covered in a thin semi-transparent polypropylene mulch to help maintain even temperatures, reduce water loss and protect the crop from insects. The mulch generally only lasts for one season and then it has to be collected up and returned for recycling. This is a complex and expensive process. A bioplastic mulch that will dissolve in the soil over the winter is much better because it saves time and money but also adds to the carbon content of the soil, helping to maintain fertility. In other important agricultural uses, such as for strimmer cord (‘weedwacker’ in the US, full biodegradability means that small pieces of plastic filament do not persist in the environment.

Another example, likely to become one of the largest single applications for bioplastics, is single use catering utensils. Restaurants and coffee shops generate three streams of waste: unused food, packaging (for example of sandwiches) and utensils such as cutlery. It is highly beneficial – as well as being advantageous to the brand image of the restaurant – to use fully compostable packaging and utensils. All the waste can be put into one bin and shipped to the composting facility without further intervention or labour cost. The thick pieces of plastic cutlery will need to shredded at the composting site to encourage rapid biodegradation but this can happen automatically. Although fully degradable cutlery costs about four times as much as conventional plastic utensils, the reduction in time spend separating out plastics from food waste and,second, reducing landfill cost, more than justifies the expense.  As well as compostable utensils, it makes sense to use bioplastic film to provide the windows in cardboard sandwich packets so that the packaging can also be added to the stream of compostable items.

Some American towns and cities are beginning to move to mandatory use of biodegradable plastics for single use catering utensils, including plates, cups and cutlery. Seattle, for example, has introduced an ordinance that obliges restaurants to only use bioplastics that will degrade in the city’s composting plant. The final imposition of this rule has been delayed by problems obtaining cutlery that is sufficiently compostable but the rules are becoming stricter here and in other towns and cities wanting to reduce use of landfill.  Seattle uses a landfill site 320 miles from the city - about the distance from Newcastle to London - creating a huge incentive to avoid high transport fees.[16] As disposal sites fill up around the world, the need either to recycle plastics or to compost them can only increase, adding further buoyancy to bioplastic sales.

In a similar move, municipalities around the world collecting food waste from homes are now often providing compostable plastic bags into which the food goes prior to collection. Householders benefit from easier and more hygienic storage of the waste. The municipality can collect the bag and does not have to separate it from the waste food before the composting process begins. While these bags are not as strong as the equivalent standard polyethylene bag, they perform their functions well.

c)       Litter

The best understood advantage of biodegradable bioplastics lies in the reduction of permanent litter. Plastic single use shopping bags are the most obvious example of how plastics can pollute the environment with huge and unsightly persistence. A large fraction of the litter in our oceans is of disposable plastic bags. Cities and countries around the world are taking action against the litter, sometimes by banning non-degradable plastic bags entirely. Italy has decided to block the use of non-biodegradable single use shopping bags from the beginning of 2012. The city of Portland, Oregon has just (July 2011) joined several dozen US municipalities in banning most plastic bags. These legislative changes represent a clear trend as politicians respond to the irritation over the persistence of plastic bag litter in the world’s seas, rivers and rural and urban environments.

Some places will continue to allow plastic bags that are genuinely biodegradable and meet the published standards for compostability. (Bags that are oxy-degradable, and only break down in to very small pieces rather than truly biodegrading, will generally be banned). Biodegradable bioplastic bags will be allowed in Italy, providing a huge boost to the European market for these products not least because until now the country has been the largest European market for single use shopping bags.

Bioplastics demand will continue to grow.                                                                                     

Continued research and development in bioplastics is creating high quality products for a wide variety of industries. Now that the benefits of biologically sourced plastics are well-understood, their market share is likely to rise sharply. The three drivers of growth – the importance of brand image to consumer goods companies, the value of joint composting and the reduction of litter – will provide the spur for continued growth in bioplastics across the world.

The carbon footprint of plastics

Calculating the greenhouse gas reductions arising from the use of bioplastics is a complex and controversial area. But it is nevertheless important to try to quantify the benefits from making plastics from biological materials in order to encourage further debate and research.

The first point to make is that the carbon footprint of a bioplastic is crucially dependent on whether the plastic permanently stores the carbon extracted from the air by the growing plant. A plastic made from a biological source sequesters the CO2captured by the plant in the photosynthesis process. If the resulting bioplastic degrades back into CO2 and water, this sequestration is reversed. But a permanent bioplastic, made to be similar to polyethylene or other conventional plastics, stores the CO2 for ever. Even if the plastic is recycled many times, the CO2 initially taken from the atmosphere remains sequestered.

The chart below offers illustrative figures for the greenhouse gas impact of making a kilo of bioplastic from a material such as wheat starch. The first column – a negative number - estimates the CO2 captured from the atmosphere by photosynthesis during the growth of the plant. The second records an estimate of the greenhouse gases emitted in the process of producing the wheat. This includes the emissions from fossil fuels used to power the tractor and other energy use in the field and in the drying of the wheat. It also measures the impact of fertiliser manufacture and the emissions of nitrous oxide, a very powerful global warming gas, as a result of the chemical breakdown of nitrogenous fertiliser in fields.

The third column estimates the CO2 impact of the energy used in converting the starches to a plastic. This figure will generally be much lower than the figures for oil-based plastics because biological materials need much lower temperatures and pressures in the manufacturing process. Bioplastics can generally be processed at about 140-180 degrees Celsius compared to temperatures of around up to 300 degrees for conversion of petrochemicals to plastics.

 

Chart A

The greenhouse gas implications of making a simple polymer plastic from wheat

(These numbers are illustrative – kilogrammes of CO2 equivalent per kilogramme of plastic produced)

-1.4 CO2 sequestration by growing plant

+0.6 GHGs emitted by farming

+2.0 GHGs produced by conversion to plastic

+1.2 Net carbon footprint

Sources: Sequestration in wheat, http://ec.europa.eu/environment/ipp/pdf/ext_effects_appendix1.pdf, GHGs from wheat cultivation, ’How Bad are Bananas’ Mike Berners Lee, Profile Books, 2010, GHGs from conversion processes, estimate from Biome Bioplastics. CO2e is a measure of emissions by which all different greenhouse gases are standardised to the global warming impact of CO2.

Most calculations of the energy used and greenhouse gases created in the production of conventional plastics produce much higher numbers. One estimate of the CO2 produced per kilogramme of oil-based polypropylene is 3.14 kilogrammes per kilogramme of plastic.[17]  This compares with the 1.2 kg illustrative figure for wheat polymers in the chart above.  To be clear, the implication is that those bioplastics that do not degrade might therefore have a carbon footprint of well under half the conventional equivalent.

Braskem, the large Brazilian producer manufacturing both bioplastic and oil-based equivalents, has calculated much higher figures for the capture of CO2 by a growing sugar cane plant. It estimates a net sequestration (that is, a negative footprint) of about 2.3 kilogramme of CO2 for every kilogramme of biopolypropylene manufactured.[18] It compares this to a carbon footprint of over 3 tonnes for polypropylene made from oil, meaning a net gain of over 5kg of CO2 for each kilogramme of plastic. This is an important potential saving; if all plastics were switched to biological feedstocks and the carbon footprint benefit was as high as much, the reduction in global greenhouse gas emissions would be about 5% of current total.

If, on the other hand, the bioplastic is of a degradable type the advantages over conventional plastics are less pronounced. The plastic will compost back into carbon dioxide and water, returning all the sequestered carbon to the atmosphere. In the illustration given above, the savings from making the bioplastic compared to the oil-based comparator would be relatively small, but nevertheless still positive. The crucial point – not well understood by commentators or by the public – is that compostable plastics will typically have a much larger carbon footprint than ones that are manufactured to be permanent. The return of the CO2 to the air reduces the sequestration of organic material.

This situation would be made worse if the bioplastic did not compost in air, but rotted in an oxygen poor landfill. In these circumstances, the plastic would degrade into methane (CH4) and other byproducts. Methane is a global warming gas of greater impact than CO2 and so the full carbon footprint needs to include any uncaptured CH4 produced in landfill.[19] Most - but not all - research shows that the conditions in well maintained landfill sites are too dry for degradable plastics to actually rot. In these circumstances, the bioplastics will therefore permanently sequester carbon. More work needs to be done on this issue, but in the intervening time the precautionary approach is to try to ensure that all biodegradable bioplastics are kept out of landfill.

The other advantages of bioplastics

We have identified five major advantages of bioplastics in this note

  • Potentially a much lower carbon footprint
  • Lower energy costs in manufacture
  • Do not use scarce crude oil
  • Reduction in litter and improved compostability from using biodegradable bioplastics
  • Improved acceptability to many households

There are also some significant technical advantages to bioplastics; these depend on the precise plastic used and how it is made. Products characteristics of value can include

  • Improved ‘printability’, the ability to print a highly legible text or image on the plastic
  • A less ‘oily’ feel. Bioplastics can be engineered to offer a much more acceptable surface feel than conventional plastics
  • Less likelihood of imparting a different taste to the product contained in a plastic container. Milk, for example, will acquire a new taste in a styrene cup but the bioplastic alternative has no such effect.
  • A bioplastic may have much greater water vapour permeability than a standard plastic. In some circumstances, such as sandwich packaging, this can be a disadvantage, but in the case of newly baked bread a bioplastic container will offer a significant advantage in letting out excess vapour or steam.
  • A bioplastic can feel softer and more tactile. For applications such as cosmetics packaging, this can be a major perceived consumer benefit.
  • Bioplastics can be made clearer and more transparent (although they are usually more opaque)
  • Plastics made from biological sources still need to contain additives such as plasticisers that give the product its required characteristics. But bioplastics do not contain bisphenol A, an additive thought to leak from plastics and which is an endocrine disruptor and mimics sex hormones. Bisphenol A is not yet banned in most countries because the chemical is rapidly excreted by most creatures, including humans. But the high levels of continuing exposure to this worrying chemical from conventional plastics may mean that consumers will want to avoid this chemical and shift to safer bioplastic alternatives.

Bioplastics are an important part of the move to a more sustainable world.                            

Bioplastics, currently accounting for less than half of one per cent of all plastics manufacture, are growing rapidly because of the clear advantages they have in many applications. As oil supply tightens, these advantages will grow. Their carbon footprint can be much lower than oil-based equivalents.  Bioplastics can provide excellent biodegradability, helping the world deal with the increasing problems of litter, particularly in the world’s rivers and seas. Durable plant-based bioplastics can also be recycled as well as their conventional equivalents, assisting the growth of a more sustainable world economy.

 

 

Chris Goodall

chris@carboncommentary.com

+44 07767 386696

 

(This research was commissioned by Biome Technologies, a major European bioplastics company. A full version is available at www.biomebioplastics.com)

[1] Comparing the greenhouse gases to make a water bottle, the New York Times reported that steel is fourteen times worse than plastic. (http://www.nytimes.com/interactive/2009/04/19/opinion/20090419bottle.html). G Magazine in Australia suggested that recyclable plastic water bottles had up to 80% less global warming impact than steel or aluminium alternatives http://www.gmagazine.com.au/node/2436/full

[2] Incpen, an industry trade body, provides analysis of comparative carbon footprints for various types of packaging. One example showing that plastics are better than glass is provided here http://www.incpen.org/resource/data/ipen1/docs/PRAG3LCAMeasTools.pdf

[3] The UK Environment Agency produced a report in early 2011 that suggested that supermarket paper bags had three times the environmental impact of single use polyethylene bags. http://publications.environment-agency.gov.uk/PDF/SCHO0711BUAN-E-E.pdf

[4] Some conventional plastics can be made to break down. However readers should be aware that many such plastics, often termed ‘oxy-degradable’, do not actually degrade into smaller molecules. Rather, they simply break into very small pieces. This reduces the visual problem caused by litter, but the wider concerns remain. For example, birds and fish eat the small pieces of plastic, thinking them to be food.

[6] Dow Chemical expects its proposed Brazilian bio-polyethylene plant to produce plastic at about the same cost as the oil-based equivalent. http://www.technologyreview.com/energy/38114/

[7] These figures are based on calculations offered by European Bioplastics at www.en.europe-bioplastics.org

[8] Michael Carus and Stephan Piotrowski, Land Use for Bioplastics, Bioplastics Magazine, 04/09

[11] Business Green, 17th November 2009, ‘Coca Cola launches bioplastic PlantBottle.’

[12] Press release from Proctor and Gamble, August 12th 2010, ‘P&G Announces Plan to Use Innovative Sustainable Packaging’.

[13] Press release from Nestle, July 29th 2011, ‘Nestlé launches bioplastic caps for milk brands in Brazil’

[14] Text taken from the SunChips website, www.sunchips.com, on August 2nd 2011

[15] Text taken from Frito-Lay website, www.fritolay.com, on August 2nd 2011

[17] This figure was calculated by Professor Ramani Narayan of Michigan State University in a study for the bioplastics company Cereplast.

[18] This number is contained in this presentation. (Page 15) http://www.braskem-ir.com.br/braskem/web/arquivos/Conference_Mar2011_Citi_1x1_v2.pdf

[19] Many landfill sites in the UK collect the methane from rotting organic materials and burn it for electricity production. Nevertheless some methane escapes and adds to global warming.