Sustainable Aviation Fuels:
A 30,000 Foot Perspective
Chapter 3
The Role of Sustainable Aviation Fuels
Section 3.6
Carbon Lifecycle Assessment Implications for SAFS

Sustainable aviation fuel (SAF) relies on comprehensive Life Cycle Assessment (LCA) to measure emissions from feedstock cultivation, processing, and use. LCA includes Direct and Indirect Land-Use Change (DLUC and ILUC) to account for emissions from land conversion and its broader impacts. These assessments are crucial for determining the economic viability of SAF technologies through carbon credits and adherence to the ICAO’s CORSIA framework, ensuring measurable progress towards greener aviation.

The quest for sustainable aviation hinges on more than just the raw economics of feedstock – it demands a vigilant assessment of the entire carbon lifecycle. Life Cycle Assessment (LCA) emerges as a pivotal tool here, capturing the cradle-to-grave emissions profile of SAF feedstocks and spotlighting their true emissions.

Life Cycle Assessment (LCA)

LCA serves as a thorough environmental audit, measuring the impact of a product’s life from raw material extraction to its eventual use and final state. For SAFs, it means tracing the emissions from cultivating the feedstock, processing it into fuel, and the resultant exhaust when it powers an aircraft.

Land-Use Change Emissions within the LCA Framework

  • Direct Land-Use Change (DLUC): This metric reveals emissions from land transformed for biomass cultivation post-2008. It’s a direct measure, evaluating the carbon cost when, say, a forest becomes a biofuel crop farm.
  • Induced Land-Use Change (ILUC): ILUC considers the ripple effects – like the deforestation that might occur elsewhere to maintain food supply levels after farmland is repurposed for biofuel crops.

Both DLUC and ILUC are vital cogs in the LCA machinery, adding depth to our understanding of each feedstock’s emissions narrative.

sketch of farm field with small house

LCA Impacts Economics

The economic ripples of LCA are profound, particularly when it comes to carbon credits—modern economy’s “green” currency. Policies incentivizing emission reductions can make LCA outcomes financially significant, determining which SAF technologies are economically feasible based on potential carbon credit gains.

Carbon Accounting for SAFs

The ICAO’s CORSIA framework provides the rulebook for calculating SAFs’ life cycle GHG emissions. It’s a yardstick for CORSIA’s carbon offsetting efforts, with a global average baseline of 89.0 g CO2e/MJ for conventional jet fuel providing the benchmark [57]. Against this backdrop, we’ll dissect the GHG life cycle emissions for various feedstocks, seeking those with a marked edge in emission reductions.

This intricate blend of emission and economic considerations ensures that the path to a greener aviation future is paved not just with intentions but with actionable, quantifiable progress.