Report Results for
Report Results for Proganic What do these results mean for the Proganic compound? For this, the nova- Institut has carried out a simple model calculation, to be able to estimate the environmental impact of Proganic in the different categories mentioned. The Proganic material consists of PLA, PHB, minerals and carnauba wax. The greenhouse gas emissions and the use of fossil resources in the production of Proganic are significantly determined by the components PLA and PHB. For the model calculation, in both impact categories the data of NatureWorks LLC and Metabolix Inc were used. For the minerals, a greenhouse potential of 75 kilograms CO 2 equivalents per kilogram of mineral is assumed. From carnauba wax, having the lowest mass fraction, no relevant influence is to be expected. Furthermore the compounding and transport processes were included in the calculation. The result: Calculating the greenhouse potential of Proganic yielded an amount of 0.5 kilograms of CO 2 equivalent per kilogram of that bio-based material. The use of fossil resources was calculated at 27 megajoules per kilogram of Proganic. This means that if the production of PLA and PHB, in comparison with the production of petrochemical plastics, leads to lower greenhouse gas emissions and a lower use of fossil resources, this is also to be expected for Proganic itself, according to our calculations. Figure 1 shows can see the respective values marked with the asterisk. Further results of the Meta-analysis Compared with bio-based plastics, petrochemical plastics have already come a long way in their development. For this reason one can assume that the learning curve for an efficient production of bio-based polymers in the coming years will rise to the same degree as the bio-plastics market is expected to grow. Along with that, the need for research increases, particularly the need for advanced methods for assessing the environmental impact of bio-based polymers. In addition to the development of standards for taking into account the temporary storage of carbon in bio-based products, there is a lack of knowledge with regard to the impact of indirect changes in land use as well as the carbon dynamics on agricultural land. Sensitivity analyses and dynamic models can make a positive contribution to advancing the existing methods. The results of the meta-analysis show that the environmental impact of biobased polymers also depends on the relevant renewable resource basis. The question of which renewable resources cause the lowest environmental impact, however, cannot be conclusively answered due to the inadequate data base. But in general one can say that the use of by-products does improve the area efficiency of renewable resources and thus the life cycle assessment of biobased polymers. Here the use of agricultural by-products (e.g. corn straw, sugar cane bagasse, etc.) for the generation of process energy (heat, power) improves the life cycle assessment as well as their utilisation as an additional source of raw material (2nd generation biopolymers). www.bio-based.eu/ecology www.nova-institut.eu www.proganic.de 48 bioplastics MAGAZINE [02/12] Vol. 7
Methodology for the ecological assessment of bio-based and petrochemical plastics The life cycle assessment (LCA) method is used to analyse the ecological impacts of a production system; it is internationally standardised (ISO 14040). A meta-analysis of different life cycle assessments for bio-based polymers such as PLA and PHA, in contrast to looking at only one single life cycle assessment, makes it possible to give an overall view of the ecological ‘pros’ and ‘cons’ of the use of PLA and PHA in comparison with the use of polypropylene and other petrochemical based plastics. A meta-analysis is a statistical method to define similarities and differences in the results of different studies and to analyse the reasons for their respective nature and extent. Due to the particular importance of the topics on the use of fossil resources and climate protection in the public debate, the content focus of the meta-analysis is restricted to two categories of ecological impacts. Here the use of fossil resources is understood to include all fossil resources that are materially or energetically used for the production of the plastics (in MJ/kg). The greenhouse potential, expressed as CO 2 equivalents per kilogram of plastics, serves as an indicator for climate protection. The studies looked at are so-called ‘cradle to gate’ analyses, i.e. the environmental impacts looked at are analysed from the cradle (i.e. the cultivation of renewable resources) to the factory gate (i.e. preparation of plastic resin). So all subsequent phases of the product life cycle, such as the utilisation phase or the disposal phase, remain unconsidered in most of the studies. In the meta-analysis conducted, more than 30 studies on the ecological assessment of the production (material and energy flows, preliminary products) of polylactides (PLA) and polyhydroxy fatty acids (PHA/PHB) were examined, evaluated and their results compared with one another. That makes it possible to generalise statements and to draw reliable conclusions with regard to the strengths and weaknesses of the production systems analysed. The impact categories looked at in the metaanalysis are the use of fossil resources and climate change. When looking at further impact categories, ecological drawbacks may also be revealed in the production of bio-based polymers – as is inevitable with any kind of industrial use of biomass, and already seen in the agricultural cultivation of renewable resources. bioplastics MAGAZINE [02/12] Vol. 7 49
