Working Paper

Potential tankering under an EU sustainable aviation fuels mandate

European Union (EU) policymakers are developing a mandate that would require jet fuel providers to blend an increasing share of sustainable aviation fuel (SAF) into their fuel supply at EU airports starting in 2025. This raises concerns that airlines might uplift additional fossil jet fuel at non-EU airports in order to avoid purchasing the more expensive SAF blends. This is known as tankering and is already a common practice where the price of fossil jet fuel varies across airports. Tankering saves airlines money, but increases systemwide fuel use and emissions and could reduce SAF sales under a mandate.

Drawing upon ICCT’s Global Aviation Carbon Assessment model, this paper estimates the potential emissions and fuel sales impacts of tankering on flights arriving at EU airports through 2035. Results show that tankering should be minimal in 2025, but under an escalating SAF mandate could occur on almost 80% of international flights to and from EU airports in 2035. By that time, tankering could reduce SAF sales by 22% at EU airports and increase systemwide fuel use by 0.9%. This assumes that adjoining countries do not adopt parallel SAF mandates. Carbon dioxide reductions attributable to an EU SAF mandate could fall by about one quarter in 2035 as a result of tankering.

Flights originating from the United Kingdom could be responsible for half of tankered flights and excess fuel consumed. Eliminating tankering on UK flights to Europe would increase SAF sales at EU airports by almost 20% (figure). Mandating that airlines purchase SAFs at EU airports, prohibiting the carriage of excess fuel, and encouraging neighboring nations to adopt equivalent mandates could help safeguard the integrity of an EU SAF mandate.