Every year, more than 400 million tons of plastic are produced worldwide, and the trend is rising. Global plastic consumption has almost doubled in the last 20 years. By far the largest proportion of plastic products are short-lived packaging products that are usually disposed of after a single use. Conventional plastic materials are largely fossil-based and feature a resource-intensive manufacturing process. In addition, greenhouse gas emissions are caused along the entire life cycle, from the extraction of the petroleum to the disposal of the plastic product.
In response to these challenges, the European Union's Horizon 2020 project "BIO-PLASTIC EUROPE" is developing plastic materials that are both based on renewable resources and biodegradable. Researchers from the Hamburg Institute of International Economics (HWWI) are leading a work package within this project, in which they are investigating the economic as well as ecological effects of the entire life cycle of the materials developed in the project. A particularly critical issue is the cultivation of the feedstock which is used to produce the innovative plastic materials. The HWWI researchers have evaluated numerous life cycle analyses (LCA) dealing with the environmental impact of feedstock selection in bioplastics production. The analysis will serve as a basis for the selection of suitable feedstocks to produce the materials developed in the project.
The feedstocks used to produce bioplastics can be divided into three generations in terms of their degree of development. The first generation of feedstocks comprises crops such as corn or sugar cane, which also play an important role in the food industry or are used as animal feed. Currently, most bio-based plastics available on the market are produced from first-generation feedstocks. However, scientific studies show that while the intensive agriculture required to grow first-generation feedstocks can result in greenhouse gas emissions savings compared to fossil-based plastics, it is also associated with greater negative environmental impacts in other respects. For example, the conversion process of forests and meadows to produce arable land generates pollutant emissions and is associated with a significant loss of ecosystem services. Cultivating crops on already cultivated land would also not solve the problem of land competition, as it indirectly leads to similar land conversion elsewhere. In addition, the use of pesticides and fertilizers during the cultivation results in pollutant emissions to soil and water. In the long term, the emergence of monocultures also poses risks to soil quality and biodiversity. Finally, competition with food production is also a critical factor from an ethical perspective.
Second-generation feedstocks include lignocellulosic raw materials, which are mostly obtained as by-products of the cultivation of food crops such as corn and sugar. The main advantage of these feedstocks is that the by-products are produced within existing process routes for corn, sugar, or grain and thus do not create environmental problems related to land conversion and competition with food production. However, a LCA must consider that agricultural by-products also offer benefits from an environmental perspective (e.g., erosion control, use as an energy source) that are not realized when the raw materials are used for bioplastic production. Therefore, it is important that opportunity costs of alternative use are also considered in the environmental analysis.
The third generation of feedstocks for bioplastics production includes the most innovative forms of raw material extraction, which are, however, currently still at an early stage of development. These include, for example, biomass from algae or from industrial and household waste. In contrast to first- and second-generation feedstocks, the alternative uses of these raw materials are rather limited. The use of waste materials also eliminates the need for disposal, which is usually emissions intensive. Nevertheless, this feedstock category also has its own environmental risks, which are mainly related to the low maturity of the processing technology. In particular, the currently high energy intensity of the biorefinery process significantly worsens the environmental balance. In the future, however, efficiency improvements through economies of scale and process innovations, but also higher shares of renewable energies in the energy mix of producer countries, could remedy this shortcoming.
A comprehensive literature study summarizing and evaluating the ecological risks and opportunities of the different feedstocks generations is published in form of the HWWI Research Paper 194. The main results of this literature study have already been presented at the EUROPEAN BIOPLASTICS RESEARCH NETWORK (EBRN) conference on: "2nd & 3rd Generation Feedstock for Bio-based and Bio-degradable Plastics" on November 4, 2020 and discussed with international researchers, company representatives and policy makers.