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02 | 2008

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Opinion Be careful what

Opinion Be careful what you wish for... Life Cycle Assessment (LCA) can be a useful tool for evaluating a product’s net environmental impact. But don’t assume it’s going to be easy, or that you will get the answer that you want. Life Cycle Assessment is a method for quantifying the net environmental impact of a product or process. The life cycle of bioplastic stretches from the growing of plants to final disposal, with manufacture, use and transportation in between. Most bioplastics aren’t 100% bio-based so the extraction and manufacture of petrochemicals has to be added to the life cycle too. With the growing awareness amongst industry, consumers and policy makers of the effects that human activity can have on the environment, and mounting pressure to make products more sustainable, LCA seems like a simple way for bioplastics to get all the kudos for being ‘eco-friendly’– isn’t it just putting a load of numbers into a spreadsheet? Actually, LCA is simple to say, but not simple to do. For an LCA to be any use, the data that goes into it must be of good quality. This means finding relevant, precise, complete and up-to-date information. However, these criteria aren’t easy to satisfy. Changes in technology mean that data can rapidly become obsolete. An LCA is just a reflection of the data at the time it was performed so they must be revisited to keep them relevant. This also means that comparing LCAs done at different times can be fruitless as you probably won’t be comparing like-with-like. Further complications come from the proliferation of LCA software available, each one using different assumptions and calculations. These assumptions must be analysed in depth to understand individual LCAs and to make accurate comparisons between similar LCAs. Whilst LCA might seem a great way of comparing your bioplastics to other products on the market, are your competitors really going to let you get hold of commercially sensitive information, particularly if it could make their environmental policy look undistinguished? If you’re relying on secondary sources of information, the LCA conclusions could be invalid. It is better to view LCA as a tool that can be used internally to improve the life cycle of your own products. It is also important to remember that LCA is not the culmination of environmental management, but is actually the beginning of the process. LCA identifies the environmental ‘hotspots’ in your production process where making changes will really have an impact. By exploring the options through an LCA, manufacturers can ensure they are not simply transferring environmental burdens from one stage to another, or, importantly in our globalised economy, from one country to another. As an example of the application of LCA to bioplastics we can look at the results of an LCA on single-use carrier bags. UK government and supermarkets have expressed a commitment to abandon HDPE bags and replace them with something more ‘environmentally friendly’. Before any rash 36 bioplastics MAGAZINE [02/08] Vol. 3

Opinion decisions are made, assumptions should be set aside and the life cycle of each alternative choice should be evaluated. Defra funded a study, commissioned by the NNFCC and carried out by Imperial College London, to examine the issues. The study looked at the life cycles of four different bags: a typical HDPE carrier bag, used as the reference product; an oxo-degradable lightweight bag made from HDPE with an added catalyst that makes it breakdown in sunlight; a biodegradable MaterBi bag; and a prototype biodegradable bag made from formulations of NatureWorks PLA and BASF Ecoflex. The results showed that waste management scenarios considered in an LCA greatly influence the outcome. The option with the least environmental impacts in the investigation was actually HDPE carrier bags disposed of via an efficient recycling process with 90% avoided product. However, such efficient recycling is currently not a realistic scenario. The next best option is the use of Mater-Bi bags, preferably disposed of by incineration which gives a slightly better environmental profile than composting or landfill. Oxo-degradable bags disposed of via incineration or landfill are the next best options followed by the heavier HDPE bags disposed of via incineration or landfill. The prototype biodegradable bag initially presented the worst environmental profile, but a ‘bad’ LCA result doesn’t mean the product is ‘bad’; it just shows where there is room for improvement. These bags are relatively heavy, but the LCA demonstrates the environmental benefits of reducing their mass. A lighter bag improves the environmental profile down to a level at which they perform better than HDPE bags and only slightly worse than the Mater-Bi bags, indicating that further development of these bags offers much potential for environmental improvement. So which is the best bag? There isn’t a clear ‘winner’, so the answer depends on how you view the alternative waste disposal methods. The takehome message is that the LCA has provided useful information, but hasn’t relieved us from making difficult decisions. LCAs can be worth the time and effort that is put into them as long as you bear in mind these key points: • (1) It’s just a tool! • (2) It is a snapshot of constantly changing reality. • (3 ) LCA is not the end of a process but the beginning. • (4) LCA can help to identify the environmental hotspots in your production process. • (5) Comparing products can be very difficult. LCAs have shown that bioplastics can have significantly lower environmental impacts than petrochemical-based plastics; however, the issues of scale-up, functionality and evolving waste streams must be considered to maximise market penetration of sustainable products. Bioplastics manufacturers should accept that LCA is part of your toolkit, rather than the definitive solution. Article contributed by Dr. John Williams, Technology Transfer Manager, and Dr. Louise Dommett, Science and Technology Writer The National Non-Food Crops Centre, York, UK bioplastics MAGAZINE [02/08] Vol. 3 37

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