Opinion Pro energy
Opinion Pro energy recovery • Energy recovery is possible for all types of bioplastics and their composites, regardless of their raw material basis and compostability. Composting by contrast is restricted to entirely compostable bioplastics, making their certification (e.g. to EN 13432) crucial. • Ecological advantages of bioplastics packaging made from renewable resources over petrobased plastics packaging mainly stem from their energy recovery after use. They thus can help to substitute fossil resources such as coal, natural gas and oil in a twofold way: first in the production of the packaging material, then in their second use as a climate neutral energy carrier. • As energy recovery is only impaired by chlorine or heavy metals, there are no problems to be expected from the processing of used bioplastics currently on the market. On the contrary, biobased plastics improve the environmental impact of the use of RDF (refuse derived fuels) regarding the CO 2 balance. Composting on the other hand is impaired by all inorganic components, their share being expected to rise with bioplastics being introduced to the organic waste stream (e.g. compostable and non-compostable plastics being disposed in the same bin). In order to ensure the marketability of the recycling product “compost” it then will become necessary to introduce the sorting of the entire waste stream (bio waste and bioplastics packaging) before processing it. With the arising costs to be allocated completely to the bioplastics the proclaimed cost advantage of composting over energy recovery in becoming highly debatable. • When choosing among alternative recycling routes, there are last but not least legal aspects to be taken into account. In Germany for example, the joint collection and processing of bio waste and used packaging leads to questions that arise from the “mix” of responsibilities to be taken over by the public sector for the bio waste and those to be taken over by the private industry for the used packaging. Among others these questions concern the rules and obligations to call for tenders and the bargaining over the correct splitting of costs: Aspects that challenge the practicability of such a jointly used system as well as its calculability. General observations: The question from which and how many ecologically efficient recycling methods for bioplastics you may choose in the long run is closely related to the choice of the collection system and the nature of the materials to be collected by it. The use of bio waste bins for the collection of bioplastics packaging does exclude particular types of bioplastic packaging (namely all those that are not compostable) and moreover restricts - due to the nature and inevitable mixture with bio waste - the choice (and competition) among alternative ecologically efficient recycling routes. Dr.-Ing. Michael Heyde Head of Technology Development Der Grüne Punkt - Duales System Deutschland GmbH Who is “Der Grüne Punkt - Duales System Deutschland GmbH”: Founded 1990 in anticipation of the Packaging Ordinance, Der Grüne Punkt - Duales System Deutschland GmbH (DSD) organises nationwide the separate collection, the sorting and, in the case of plastics, the recycling of used sales packaging in Germany. For further information on the DSD core business and other service offers see www.gruener-punkt.de. This confrontation shall form the initiation of a wider discussion. There will be more extensive description and reports about the different recovery options in our coming issues. We encourage you, our readers, to send us your opinion to editor@bioplasticsmagazine.com. German „yellow bin“ bioplastics [06/02] Vol. 1 33
Basics Degradable – Biodegradable – Compostable Biobased and biodegradable plastics can form the basis for an environmentally preferable, sustainable alternative to current materials based exclusively on petroleum feedstocks [1]. If products are biodegradable and compostable, additionally to an energy recovery option biological recovery can be applied (see also page 32/33) A closer view to the expression “biobased” will be given in one of the next issues of bioplastics MAGAZINE. This article will discuss the different terms degradable, biodegradable and compostable, all of which are often mixed up when talking about bioplastics. When designing a new product, it is important to consider its ecological footprint especially as it relates to its ultimate disposability. Of particular concern are plastics used in single-use, disposable packaging and consumer goods. Designing these materials to be biodegradable and ensuring they end up in an appropriate disposal system is environmentally and ecologically sound. For example, by composting biodegradable plastic and paper waste along with other „organic“ compostable materials like yard, food, agricultural wastes, much-needed carbon-rich compost (humic material) can be generated. Compost amended soil has beneficial effects by increasing organic carbon, increasing water and nutrient retention, reducing chemical inputs, and suppressing plant disease. Composting is increasingly used for maintaining the sustainability of the agriculture system. In many countries food wastes along with other biowastes are separately collected and composted to generate a good, valuable soil amendment that goes back on the farmland to reinitiate the carbon cycle [1]. Polymer materials have been designed in the past to resist degradation. The challenge is to design polymers that have the necessary functionality during use, but disintegrate after use. More importantly, the breakdown products should not be toxic or persist in the environment, and should be completely assimilated (as food) by soil microorganisms in a defined time frame. In order to ensure market acceptance of biodegradable products, the ultimate biodegradability of these materials in the appropriate waste management infrastructures (more correctly the assimilation/utilization of these materials by the microbial populations present in the disposal infrastructures) in short time frames of a few weeks only needs to be demonstrated beyond doubt [1,3]. However, the above still does not give a clear differentiation between the expressions degradable, biodegradable and compostable plastics. Here is a try: 34 bioplastics [06/02] Vol. 1
