Will so called bio-plastics enable mankind to have all of the benefits of plastics with less of the issues for the environment?
Like it or not we live in a world in which we currently consume more than the planet can sustain. There is a mindset that encourages us to dispose of what we have and move on to the next. As such it represents a powerful challenge if global society is to move forward in a sustainable way, whilst recognising that resources are limited.
The plastics industry has for some time recognised the need to minimise its impact on the environment through its products and production processes. Such thinking lays at the root of the developments of what are often loosely termed bio-plastics. For many, developments in this area represent something akin to a universal panacea for minimising the impact of plastics on the environment and who believe the industry should focus disproportionally on their development. Unfortunately life is not quite that simple.
For example even the term bio plastics is actually not very precise. Such materials should preferably be termed bio – based and or bio – degradable depending upon a number of factors. The distinctions are subtle but significant.
Bio based plastics
Concerns about the depletion of fossil fuel resources have lead to efforts to develop new technologies in order to replace conventional oil and gas based plastics by others based on raw materials derived from renewable sources, often covered by the catch all term “biomass.”
Plastics (or more generally, polymers) are long chains of molecules. Such molecules – the basic building blocks – can be derived from natural and renewable resources such as wood (cellulose), vegetable oils, sugar and starch.
In theory many polymers can be synthesised in this way from renewable feedstock. For example corn starch can be hydrolysed and used as the fermentation feedstock for bio-conversion into lactic acid, which can in turn be used to create the recently developed plastic called poly lactic acid orPLA.
Rather than produce new plastic materials, another approach is to make well established plastics such as polyethene, whereby the basic building block- ethylene- is derived from renewable feedstock by first producing ethanol from sugar cane.
Bio-degradable and Compostable Plastics
The plastics industry is often challenged by the public to make more biodegradable products. It is argued that it would be a great help if plastics could simply disappear by natural causes after their useful life has expired. Indeed there are many good reasons for such a desire and products to match, but unfortunately it wouldn’t be right for everything for equally good reasons.
To understand this point it is necessary to recognise that every polymer will eventually degrade – the only question is when? The answer depends upon many factors including the type of polymer and the environment it is exposed to. Degradability can be measured on a sliding scale where the key criterion is the level of change in its initial properties due to chemical cleavage of the chain of macromolecules that it was built from.
Plastics designed to degrade comparatively quickly include oxo-degradable and UV degradable polymers that break down when exposed to oxygen or light respectively. .
To qualify as bio-degradable, however, this degradation has to happen, at least in part, due to cell mediated phenomena or microorganisms. As a result the polymer is eventually reduced to water, carbon dioxide, biomass and possibly methane.
There is not necessarily a direct correlation between bio – based products and biodegradability. For example some bio-based products such as polyhydroxyalkanoates are often bio-degradable where as others such as polyethene are not, even, if they have been derived from sugar cane. The key is the molecular structure of the resultant polymer.
To be considered as compostable it must meet some strict criteria as defined in national and international standards:
- Biodegrade: break down into carbon dioxide, water and bio mass.
- Disintegrate; after three months composting and subsequent sifting through a 2 mm sieve no more than 10% residue may remain.
- Eco toxicity: the bio-degradation does not produce any toxic material and the compost can sustain plant growth.
These few paragraphs are intended only to present some of the arguments around bio based and bio degradable plastics. We are interested to hear what you think. Why not enter the online debate?
I think it is a shame that so many people don’t realize or understand the usefulness of plants as replacement sources for products made from wasteful petroleum. Americans resist hemp paper (which could save trees) simply because they don’t understand the difference between a drug and a crop. It is important to educate people about the positive options available to reduce our dependency on petroleum products.
I think the main issue with making plastics with bio-mass is one of quantity. There isnt a proven way to produce plastics from bio-mass on a large scale that I’m aware of yet. This would be a real breakthrough if we could find it…
I’m delighted that this new web site hasbeen set up,we need to do a heck of alot more to raise public awareness.
My greatest concern about the whole plastic issue is that very little is mentioned about oil being finite, it will run out one day, be it 100,500 or 1000 years &we; are not being fair to future generations. Bio plastic can only scratch the surface.
Burning waste plastic is a waste of a resource,it is no different than burning oil,and whats the point if we waste the energy once we have generated it?
Recycling plastic is not rocket science,it just needs the capital, which the government are reluctant to stump up. We also need cheap renewable energy for recycling so that the products we can make are at a price competitve to products made from virgin oil, only then can the recyclingindustry be sustainable. Phil, Cornwall
Should we be making plastics out of biomass?
I guess this raises a similar question to the bio-fuels industry: should an empty stomach be in direct competition with an empty petrol tank (bio-fuels) or feed stocks for drinks bottles (bio-polymers).
Their adoption and use would be pretty good (especially due to the reduced environmental damage through rapid decomposition), but is the aim to create materials that are more sustainable and lessen mankind’s impact on earth or are we trying to alleviate our consciences by not using ‘dirty dirty oil’? All of the corn used as raw feed stocks will have required rather intensive farming, which is of course energy (and potentially fossil fuel?) hungry.
How about we think of the existing polymer materials as a quantity of valuable materials the “pool of materials”. Then we use the 4R’s doing our utmost not to deplete the pool of available materials to keep making things from?
The biomas basis for making new polymers should perhaps be from agricultural and horticultural waste rather than from food growing land. Meaning food comes first and from the processig waste we make new polymer materials.
Kosmo Vinyl
10 July 2009, 22.59
“I think the main issue with making plastics with bio-mass is one of quantity. There isnt a proven way to produce plastics from bio-mass on a large scale that I’m aware of yet. This would be a real breakthrough if we could find it…”
Plastics are in fact already being made out of basic materials derived from biomass, and on quite a large scale. There is however currently much discussion on whether food crops should be used for such purposes. It is expected that the basic chemical building blocks for plastics will increasingly be produced from sources such as algae and other non-food sources.
Replying to: phil kennen
12 July 2009
“I’m delighted that this new web site hasbeen set up,we need to do a heck of alot more to raise public awareness.
My greatest concern about the whole plastic issue is that very little is mentioned about oil being finite…”
It is clear that at some time in the (distant) future oil may be either depleted or too expensive to extract. However the use of biomass to produce raw materials to make plastics is certainly not an unrealistic dream. Such processes already exist making the materials for either new plastics or well established ones such as polyethylene.
As for the need for cheap renewable energy, this is something on which we can all agree as being desirable.It would allow many processes to become competitive with conventional oil based systems. But in the meantime we should not underestimate the importance of innovation in general in reducing, for instance, the amount of plastic required for a given application as well as efficiency improvements in logistics and handling systems.
Finally it should be noted that burning plastics does not need to be a waste of resources. Post-use plastics are a high calorific fuel which can help save the resources of traditional fossil fuels. And even municipal incinerators in Europe are obliged to recover energy from the household waste which is burned.
Replying to: Malcolm
13 July 2009
“How about we think of the existing polymer materials as a quantity of valuable materials the “pool of materials”. Then we use the 4R’s doing our utmost not to deplete the pool of available materials to keep making things from?…”
The concept of a “pool of materials” which are continuously recovered and recycled in an interesting one. It can, for example be usefully applied with specific metals which can be readily collected and sorted prior to re-processing. However , with other materials such as paper and plastics it is more difficult as there is a reduction in physical properties on processing, and a variety of different types which are difficult (and energy intensive) to separate. This is why there should be a degree of flexibility in applying the 4 R’s. An example where the ‘pool of materials’ concept does work with plastics is with the recycling of carbonated drinks bottles which are all made from the same plastic and are readily identified and collected.
As regards using biomass as a source of raw materials for plastics, it clearly makes sense to focus on waste agricultural products where possible. There are also interesting developments in making raw materials from non food biomass such as algae.
Just a word of warning about ‘energy from waste’ ie burning the plastics.
I live on an island that went down the EfW route and all it does is encourage more waste of ever depleting natural resources (you have to feed the beast once you’ve built it and KEEP feeding it endlessly) PLUS and this to me is a big and controversial point burning certain types of plastics produces dioxins.
The incineration industry will tell you the filtration/extraction now is ‘best practice’ but it only takes minute amounts of dioxins to poison people and as the incinerators get older they aren’t necessarily kept to best practice – in our case here on the IoM the plume of the mass burn incinerator drifts across our biggest populated town!?
Sad to say the UK is going down the route more and more of EfW.
Plastics should be made to maximise the 4R’s principle and if they can’t then please don’t make them.
I’m of an age where I can remember using/collecting glass bottles and things were reused, now in our throwaway societies very little is – if the oil prices went off the scale again then plastics wouldn’t be so cheap to use…… and wasted less.
Phil
As a member of the Plastics 2020 Challenge I would like to respond to your posting from an industry perspective. The first point to make is that I hope we agree that that we should get the maximum level of efficiency from any resource that society uses? That is why we are proposing to double the rate of plastic packaging recycling in the UK by 2020 and use the non-recyclable as fuel in EfW plants. The videos on the recycling debate on this site reveal how a cross section of opinion formers think this might be delivered. This is part of a wider goal to prevent waste plastic from going to landfill or anywhere else for that matter including the marine environment. Part of this strategy must include EfW as this is the most practical way of recovering the stored energy in plastic as well as other waste. The evidence from Germany, Austria and my native country Sweden, who have all invested in modern EfW facilities, is that recycling and EfW can happily co exist and that recycling levels of plastic can actually increase year on year. The important point is that these countries send almost nothing to landfill, which is a complete waste of precious resources.
We acknowledge that your concerns about the environmental impact of EfW are sincerely held and shared by many, but the declared judgement of the Environment Agency and the Health Protection Agency, who are charged with regulating such matters, is that modern EfW plants operate safely and have no adverse health impacts on the population around them. As these judgements are made on the back of extensive and peer reviewed science it is difficult to know how much more reassurance can be provided and by whom? I live myself near an EfW plant in Gothenburg and I can assure you I have no reservation over this. In fact the air leaving the chimney is cleaner than the air I breathe when I walk on the streets of Gothenburg.
That said, please be assured that the industry sees energy recovery as an option only for such plastics which cannot be recycled in an economically an environmentally beneficial way.
To achieve the objective of the waste hierarchy to divert waste from landfill we need to develop the infrastructure to facilitate plastics recycling and recovery and encourage government, both national and regional and industry, to keep investing in it during what are sure to be difficult economic times.
No. I recently did a little work on Bio-plastics such as PLA. I have worked with Bio-plastics for over 7 years, when they were sold as the Miracle replacement to Plastic. The issue with Bio-Polymers is four fold:
1) they use huge quantities of raw Materials i.e. over 10,000 kg of Sugar Beet are need to make 1,000kg of PLA
2) Huge amount of CO2 are generated growing & transporting the crops, then lots of energy is used in converting the organic matter to Bio-plastic.
3) According to WRAP last month (March 2010), the best route for disposal of Bio-polymers is not composting as we would hope, but recycling (where available????) or Incineration with energy recovery.
4) Many Bio-polymers do not have the properties we require such as strength to weight ratio, durability, life-span etc.