Life Cycle Assessment (LCA)

Process-based LCA is used in the project to support decision-making regarding the large-scale implementation of Plastics2Olefins systems. All the relevant impact categories, such as climate change and resource use, from the transport of plastic waste to the separation of olefins are quantified in the project. The LCA is conducted following the ISO 14040 and 14044 standards as well as the ILCD recommendations, while also taking the specific recommendations of modeling waste management systems into consideration [1].

The objective of the project is for Plastics2Olefins to have 80% lower carbon footprint than incineration, and 70% lower than the currently incumbent low temperature pyrolysis technology. Although goals were set only for the climate change impacts of the process, also other impacts will be evaluated to have a thorough understanding of the process. The LCA acts as a robust decision support tool by informing not only of the Plastics2Olefins system’s relative performance to competing technologies, but also the possible tradeoffs between different impact categories, and the stages where impactful improvements can be made.

The LCA is conducted comparatively with the reigning waste management systems, including incineration and more conventional low temperature pyrolysis, which will be modeled with previously calculated inventory data. The background systems, including energy and utilities, are modeled with inventories from databases implemented in the LCA modeling software SimaPro, and life cycle impact assessment (LCIA) is conducted with a recently updated and established method ReCiPe 2016.

The system boundaries in the LCA include collection and transport of plastic waste, its pre-treatment, pyrolysis, and all purification stages, as well as the steam cracking of the pyrolysis oil and the separation of olefins and other hydrocarbons. The process has several products and by-products, including olefins that can be used in the production of circular plastics, different hydrocarbons suitable to be used as fuels, and char, which may be further used as a source of heat in cement production. Different methods to assign impacts between the products are used in the LCA to see if the modeling principles affect the results and the conclusions.

[1] Laurent, A., et.al. 2014. Review of LCA studies of solid waste management systems – Part II: Methodological guidance for a better practice. Waste Management 34(3): 589–606.