Identifying and Quantifying Practical Levers for Industry Decarbonization: Lower-Carbon Electricity and Recycling

Abstract

Achieving net zero requires decarbonizing the highly heterogeneous industrial sector, and guiding action requires quantifying mitigation levers in the context of specific value chains. This dissertation identifies and quantifies practical levers for industrial decarbonization through two categories of interventions: process-focused levers, which reduce emissions within production processes, and material- and product-system levers, which take a broader systems perspective to reduce the need for high-carbon production. Using the foundational industrial ecology methods of life cycle assessment and material flow analysis, I translate these levers into quantitative, actionable metrics. The first case study examines lower-carbon electricity as a process-focused lever for decarbonizing renewable energy supply chains. I develop a life cycle assessment framework that introduces novel indicators for technosphere flows, including cumulative electricity consumption, to isolate actionable sources of embodied emissions across global supply chains. The results show that every 1 kWh of renewable electricity delivered to the grid embodies 0.009-0.035 kWh of upstream electricity for photovoltaics (PV) and 0.004-0.008 kWh for onshore wind. Supplying production chains with these specific quantities of additional renewable electricity can reduce lifecycle embodied emissions by roughly 50% for PV and 30% for wind, avoiding about 0.9-1 Gt CO$_2$-eq that would arise from PV and wind energy deployment in 2026-2030. The second case study examines recycling as a material- and product-system lever in flexible plastic packaging, a packaging format that has proven notoriously difficult to make circular. Using material flow analysis, I quantify post-consumer flexible plastic packaging flows in the United States and classify them by suitability for mechanical recycling. I find that only 3-8% of post-consumer film was recycled in 2021, while roughly one-quarter to one-half is readily mechanically recyclable, and a similar share is effectively non-recoverable under current techno-economic conditions. Mechanically recycled polyethylene can have significantly lower embodied carbon than virgin material, but the extent to which these climate benefits can be realized is limited by product design, waste composition, and collection systems. Together, the two case studies show that industrial decarbonization requires system-specific evidence that clarifies where a lever works, how much it can reduce emissions, and which actors can act on it. This dissertation contributes both new metrics and new system knowledge for translating decarbonization levers into practical interventions.