Date of Award

2017

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Materials Science and Engineering (MS)

Administrative Home Department

Department of Materials Science and Engineering

Advisor 1

Joshua A. Pearce

Committee Member 1

Stephen L. Kampe

Committee Member 2

Yun Hang Hu

Abstract

Following the goals of a circular economy, the growth of both plastic consumption and prosumer 3-D printing are driving an interest in producing 3-D printer filament from waste plastic. However, traditional recycling can have a significant environmental impact as it demands the collection and transportation of relatively low-density waste plastics to collection centers and reclamation facilities for separation and reconstruction. Compared to the traditional recycling, distributed recycling (where consumers directly recycle their own waste) has the potential to reduce energy consumption because it can save the energy for transportation needed in conventional recycling. A promising method of such distributed plastic recycling is to upcycle plastic waste into 3-D printing filament with a recyclebot, which is an open source waste plastic extruder.

In order to characterize the energy sustainability of this distributed recycling method, this study quantifies the embodied energy of a vertical DC solar-photovoltaic powered recyclebot based on life cycle energy analysis and compares it to horizontal AC recyclebot, conventional recycling and production of virgin 3-D printer filament. The energy payback time (EPBT) is calculated using the embodied energy of the materials making up the recyclebot itself and found to be about 5 days for extrusion of poly lactic acid (PLA) filament or 2.5 days for extrusion of acrylonitrile butadiene styrene (ABS) filament. The EPBT of a mono-crystalline silicon solar photovoltaic system is about 2.6 years alone. However, this can be reduced by over 96% if the solar photovoltaic system powers recyclebot to produce PLA filament from waste plastic (EPBT is only 0.10 year or about a month). Likewise, if ABS filament is produced from a recyclebot powered by solar PV system, the energy saved is 90.6-99.9 MJ/kg and 26.33-29.43 kg of ABS filament needs to be produced in about half a month for the system to pay for itself. The results clearly show that the solar PV system powered recyclebot is already an excellent way to save energy for sustainable development.

If the recyclebot is combined with an open source self-replicating rapid prototyper (RepRap) 3-D printer, then the post-consumer plastics can be turned into useful and more valuable products directly. In order to analyze the impact of combining these two methods, this project also combines the distributed recycling method using a vertical recyclebot to make filament with distributed manufacturing using a delta RepRap to print useful products from post-consumer e-waste. Specifically, this study analyzes the recycling of ABS from computer waste into valuable consumer products pre-designed in the digital commons. The total electrical energy consumption for the combined process is monitored and an economic evaluation is completed. It is clear that using traditional recycling and manufacturing methods to produce an ABS product consumes more than double the energy compared to coupled distributed recycling and manufacturing method for complex products. Even more energy is saved for simple products. Simultaneously products valued in dollars can be made for pennies using the more environmentally-responsible combined processes. It is clear from the results that in the short-to-medium term, waste plastic from discarded e-waste can be significantly upcycled at the individual level using this commons-based approach. This tightening of the loop of the circular economy is a benefit of the environment and sustainability as well as the economic stability of consumers/prosumers.

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