Sustainable bio-based materials: Application and evaluation of environmental impact assessment methods

Abstract

The global production of plastics consumes large amounts of fossil fuels. Since fossil fuels are non-renewable and their combustion emits greenhouse gases which contribute to climate change, this development is not considered environmentally sustainable. One of the ways to reduce non-renewable energy use and greenhouse gas emissions is to replace petrochemical plastics with bio-based materials, i.e. materials using biomass instead of fossil fuels as feedstock. Bio-based materials have received interest from policymakers as one of the available means to limit climate change. Replacing petrochemical plastics with bio-based materials is not straightforward however, as a large variety of new production systems can be envisioned. Not all bio-based materials or production routes result in reductions in greenhouse gas emissions compared to conventional petrochemical counterparts. This dissertation aims to support the development of low-environmental impact production routes for bio-based materials. Proposed environmental assessment methods and tools applicable during the early-stage development of new production processes are reviewed to assess the implications of applying them to bio-based materials. Furthermore, life cycle assessments (LCAs) are carried out for various bio-based materials at different stages in the production chain, to assess variability in the environmental impacts of biomass feedstock production and to evaluate the importance of additives for the overall environmental performance of (bio-based) plastics. The analyses demonstrate that bio-based materials can reduce greenhouse gas emissions and the use of non-renewable energy. However, the magnitude of these reductions is influenced by their entire production system, including where biomass feedstocks are sourced, the compositions of bio-based plastics, technical properties and reference products. Studying these factors offers the potential to maximise the environmental benefits of bio-based materials while minimising downsides. For example, the environmental impacts of bio-based materials are shown to vary based on the biomass source used and local practices. This variability should therefore be considered when developing production routes of bio-based materials. Furthermore, additives are shown to strongly contribute to the environmental impacts of bio-based plastics in some cases, highlighting that they should be explicitly taken into account in environmental impact assessments. Finally, environmental assessments can be most effective when conducted during the early-stage development of new production processes. However, the reviewed early-stage environmental assessment methods are generally not developed with bio-based materials in mind, and are often unable to quantify the environmental impact linked to agriculture that are important for bio-based materials. To take full advantage of the environmental benefits that bio-based materials can bring, early-stage environmental assessment methods that specifically target bio-based materials should be developed, and integrated into tools that can support the companies developing them.