Abstract

In recent years, many forecasts have predicted a large scale adoption of electric vehicles (EVs), which would predominantly be powered by lithium-ion batteries (LIBs), owing to their high energy and power density and long cycle life. While use of EVs could reduce dependence on fossil based transportation fuels, there is a need to understand the end-of-life (EOL) implications of retired EV LIBs entering the waste stream in future in the battery-driven vehicle regime. To proactively address impending waste management issues and inform related policy, this dissertation explored the sustainable management of LIBs after use in EVs and the challenges and opportunities involved.

First, a future oriented, dynamic Material Flow Analysis (MFA) was conducted to estimate the volume of LIB wastes to be potentially generated in the US in near and long term. The objective of tracking future outflows of EOL EV LIBs through the MFA model was to: (a) Provide an understanding of the scale at which EV LIB waste management infrastructure needs to be developed in future, and (b) Analyze the composition of future EV LIB waste stream in terms of constituent LIB packs, cells and materials. The effect of EV adoption scenarios, variability in LIB lifespan distribution, battery energy storage, LIB chemistry and form factor on the volume, recyclability and material value of the forecasted waste stream was analyzed. Because of the potential “lifespan mismatch” between battery packs and EVs, LIBs with high reuse potential are expected in the waste stream. Results of the MFA model projected annual EV LIB waste flows of as high as 340,000 metric tons by 2040. Apart from the high volume, the projected EV LIB waste streams were characterized by the presence of a variety of recyclable metals, high percentage of non-recyclable materials, high variability in the potential economic value, and potential for battery reuse. Hence, a robust end of life battery management system would include an increase in reuse avenues, expanded recycling capacity, and safe disposal routes accompanied by policy incentives to promote environmentally and economically favorable EOL management of EV LIBs.

Second, the environmental trade-offs of cascaded use of retired EV LIBs in stationary energy storage was investigated using cradle-to-grave life cycle assessment (LCA). The LCA model was framed from the dual perspective of stakeholders in the: (a) the EV sector, to understand if there is there a meaningful reduction in EV lithium ion battery environmental impact due to cascaded reuse, and (b) the Energy Utility sector, to understand if the utility sector could environmentally benefit from using refurbished EV lithium ion batteries for energy storage. In both the cases, an environmental benefit was obtained owing to avoiding the production and use of an incumbent lead-acid battery based system. However, there were diminished to no environmental benefits in scenarios where very few of the initial battery cells and modules could be reused and where service life was low in secondary application for refurbished EV LIB cells. Hence, environmental feasibility of cascaded use systems was found to be directly related to technical feasibility and reliability. An important methodological challenge addressed was the allocation of environmental impact associated with production and EOL management of LIBs across the EV and stationary use systems. The allocation modeling choices explored here were based on the concept of closed-loop recycling for material cascades. These modeling approaches can guide LCA of similar product cascade systems where a product is used for a cascaded second use in a different application.

Finally, a circular economy-inspired waste management hierarchy was proposed for EOL EVs from LIBs that included limited reuse in EVs, cascaded use in stationary applications, recycling and finally, landfill. To validate this circular economy approach, an eco-efficiency analysis was conducted across proposed waste management strategies for an EV LIB waste stream (modeled as 1,000 battery packs coming out of use in EV applications in the U.S.). Results demonstrated that a circular economy-centric waste management hierarchy can be environmentally and economically effective in managing the EV LIB waste stream in future, owing to benefits from reuse, cascaded use and recycling. However, such benefits would rely significantly on LIB size, testing procedures, the incumbent battery systems that used LIBs would displace, future prices of these batteries, and future recycling costs. Hence, these EOL management strategies would need policy and technology push to be viable. Although much attention has been placed on landfill disposal bans for batteries, results actually indicated that direct and cascaded reuse, followed by recycling can together negate the eco-toxicity burden of unavoidable metal flows into landfill. When combined with regulations deterring landfill and policies promoting life cycle approaches that additionally consider design-for-EOL, battery maintenance, collection and safe transport, circular waste management systems can be improved for these batteries. Overall, a circular waste management system for EV LIBs is likely to complement existing and guide future policies governing EV LIB waste.

Library of Congress Subject Headings

Lithium ion batteries--Environmental aspects; Electric vehicles--Batteries--Environmental aspects; Product life cycle--Environmental aspects

Publication Date

12-2016

Document Type

Dissertation

Student Type

Graduate

Degree Name

Sustainability (Ph.D.)

Department, Program, or Center

Sustainability (GIS)

Advisor

Callie W. Babbitt

Advisor/Committee Member

Thomas Trabold

Advisor/Committee Member

Nabil Nasr

Comments

Physical copy available from RIT's Wallace Library at TK2945.L58 R43 2016

Campus

RIT – Main Campus

Plan Codes

SUST-PHD

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