UC Santa Barbara

Climate change is one of the crucial challenges facing mankind. It is imperative to transition to a low-carbon economy and rapidly reduce anthropogenic greenhouse gas (GHG) emissions. Some technologies that have been growing exponentially in recent decades can be climate-friendly if managed well, but the sheer volume, rapid growth and mismanagement of them could pose great threats to climate change mitigation efforts. In this dissertation, I evaluate the opportunities to decarbonize three rapidly-growing technological systems, namely plastics, data centers and residential solar-plus-storage systems.

Current research is often fragmented in scope and there is a lack of systematic, life-cycle and prospective approaches in assessing the climate impacts of rapidly-growing technologies. By integrating life-cycle GHG emissions accounting and scenario analysis, I assess the GHG emissions mitigation potential of different strategies and interventions to decarbonize these technological systems. I also incorporate cost analysis and optimization methods into my models to assess the economic feasibility and mitigation potential of various decarbonization strategies.

In Chapter II, I quantify the global carbon footprint of plastics to be 1.7 Gigaton (Gt) CO2 equivalent (CO2e) in 2015. A low-carbon plastics economy requires demand reduction, adoption of renewable energy, renewable feedstocks and recycling. By combining these strategies, we can keep the global carbon footprint of plastics below the 2015 level in future decades. Among the strategies, renewable energy has the most potential, but sources such as solar and wind are variable in space and time. To successfully integrate them, data centers can play an important role in providing demand response by migrating workloads across regions. In Chapter III, I show that by using load migration, existing data centers in California could have reduced up to 62% yearly renewable curtailment in 2019 and 239 ktCO2e of GHG emissions with negative abatement cost, and additional data centers could reduce them further with the emissions from non-operational phases taken into account. Energy storage is another key solution for renewable energy integration. In Chapter IV, I assess the life-cycle GHG emissions and cost implications of residential solar-plus-storage systems in California. While PV reduces both emissions and cost, adding battery storage to a PV system increases life-cycle costs with mixed impact on emissions, depending on tariff structure and marginal emission factors. Emissions reduction from residential solar-plus-storage would decrease as the grid increasingly decarbonizes, but there could potentially be cost savings as storage cost declines. A marginal emissions-aligned tariff design, rapid reduction of the capital cost and embodied emissions of battery storage are critical.

This dissertation is a significant contribution to the systematic sustainability assessment of technological systems using a life-cycle approach. It serves as a solid scientific reference for policy-makers in deploying and managing rapidly-growing technologies in a way to minimize system-level GHG emissions and contribute to global decarbonization efforts.