Please join us for an E-IPER dissertation defense by Anela Arifi: "The Future of Bioenergy: Maximizing Climate Mitigation Potential from Biomass."

In-person: Y2E2 300

Virtual: Zoom webinar (password: 627777)

ABSTRACT

Biomass is humanity's oldest fuel and a cornerstone of future climate stabilization. Prominent decarbonization scenarios allocate roughly 20% of primary energy supply and over half of all carbon dioxide removal to bioenergy. At these scales, biomass can come into conflict with demands for food, biodiversity, and water, making it essential to allocate the available supply where it delivers the greatest climate benefit. This dissertation asks how biomass can be allocated to maximize climate benefit per unit of carbon.

I address this question across three chapters. In the first chapter, I combine lifecycle assessment, techno-economic analysis, and policy review to build an updated inventory of California's waste biomass energy potential through 2045. I find that biogas resources could reduce statewide emissions by roughly 8% and solid-waste resources by 1–5% depending on the conversion pathway and end-product, and that market-based fuel standards, specifically California's Low Carbon Fuel Standard and the federal Renewable Fuel Standard, are decisive for economic viability.

In the second chapter, I compare ten bioenergy with carbon capture and storage (BECCS) pathways spanning liquid biofuels, bioelectricity, and biohydrogen across 72 countries and multiple climate and socioeconomic scenarios. Previous literature has favored bioelectricity as the dominant BECCS pathway because its stationary point-source emissions are more amenable to capture than liquid biofuels. Instead, considering both capturable and avoided emissions, I find that liquid biofuel pathways deliver comparable, and in some cases greater, total mitigation per unit of biomass, making diversification essential for reaching projected removal scales.

In the third chapter, I turn to aviation, one of the hardest sectors to decarbonize and one where biomass-based fuels are among the few drop-in replacements for fossil jet fuel. I quantify the climate value of sustainable aviation fuels (SAFs) beyond their CO₂ benefits, showing that SAFs can also suppress contrail cirrus clouds responsible for aviation's dominant near-term warming contribution. Accounting for this effect reduces SAF mitigation costs by 38–78%, placing them within the cost range of widely discussed carbon removal pathways such as direct air capture, BECCS, and biochar. This reveals that current climate policy systematically undervalues SAFs as a near-term mitigation tool.

By exploring how total mitigation depends on energy carriers, conversion pathways, feedstocks, and temporospatial context, these chapters inform the deployment choices that maximize biomass's mitigation potential and the policies that can enable them, bringing the bioenergy potential of leading climate scenarios within reach.