Techno-economic and life cycle assessments of 3D printing with sustainable recycling technologies
Creators: Chitakana, Srikrishna Sai
Publisher: name: University of Alberta Library
Year: 2024

<p>This thesis investigates the economic and environmental feasibility of integrating a plastic recycling plant with a 3D printing farm in Alberta, Canada. The research focuses a techno-economic assessment (TEA) and life cycle assessment (LCA) with data-intensive modelling to evaluate the use of polyethylene terephthalate (PET) waste in an integrated mechanical recycling and 3D printing farm.<br>
The TEA involves the development of techno-economic models for evaluation of the financial viability of using PET waste input in 3D printer production to manufacture trays. Economic metrics such as internal rate of return (IRR), cost of production (COP), and profit margins are determined with a 15% discount rate over a 15-year period, including the printer life of 8 years. Capital and operating costs are calculated based on the mass and energy balance for the required recycling capacity. Sensitivity analysis identifies key economic drivers, i.e., printer production capacity, printer cost, and labor-to-printer ratio. A plastic tray weighing 22 grams and a plant capacity of 600 tonnes per year as baseline were considered. The results show that around 70% of the manufacturing cost is influenced by printer production capacity, with other factors contributing 18-20%. The optimal results are found when the farm processes 1124 tonnes of PET waste annually, with 267 3D printers at 7.04 kg/day (320 trays/day) and one operator handling 80 printers. This configuration results in a low COP of approximately $0.25 per tray and the highest IRR of 76.41%, providing a robust framework for optimizing operational parameters and supporting investments in sustainable waste management and circular economy practices.<br>
The LCA estimates the greenhouse gas (GHG) emissions through a cradle-to-grave analysis of the recycled PET trays compared to those made from virgin materials. These recycled trays are produced in the integrated farm mentioned above. The study considers mass and energy balance for different PET waste input amounts. The results show that 82% of GHG emissions are due to electricity consumption. Sensitivity analysis highlights that the electricity grid mix and printer production capacity significantly influence life cycle GHG emissions, with the grid mix affecting around 70% of life cycle emissions and other factors contributing 26-28%. The potential for more avoided GHG emissions is largely dependent on the grid mix, which contributes 91%. The highest avoided GHG emissions are observed with a renewable grid mix, approximately 57 kg CO2 equivalent per functional unit and 1500 metric tonnes CO2 per year at 1124 tonnes/yr. Annual GHG emissions trend linearly with varying PET waste input.<br>
By integrating the TEA and LCA results, this research demonstrates the feasibility of a combined plastic recycling and 3D printing operation, emphasizing both economic benefits and environmental benefits. The study provides valuable insights for optimizing recycling and production processes, fostering sustainable practices, and guiding strategic investments in advanced recycling technologies in a circular economy framework.</p>