Aviation Fuel Composition Changes to Reduce Non-CO₂ Emissions: European Refinery Impacts & Effects on Fuel Quality

Report no. 14/26: This eagerly anticipated study was launched in response to ongoing activities under the ‘European Aviation Fuel Standards Project’. The discussions here suggest that the composition of the fuel, mainly its sulphur, hydrogen, and aromatic (total aromatic and naphthalene) contents, can influence the climate impact of non-CO₂ emissions from aircraft (mainly contrails). Although there is limited scientific evidence to link non-CO₂ emissions to climate impact, the reduction of these fuel properties is known to reduce certain non-CO₂ emissions from the aircraft engine.

This study does not attempt to delve into the climate science, but it offers a useful scientific study on the ability of European refineries to reduce these fuel properties. More specifically, it informs the reader as to which refinery configurations can, and which can’t, vary these properties. On a high level, it estimates the costs of additional hydrogen, energy consumption and other OPEX, and also the capital investments required for various scenarios of incrementally tighter aviation fuel specifications. It also quantifies the additional refinery CO₂ emissions from fuel production emitted under these various fuel specification scenarios.

This study focuses on European jet fuel production based on the real refineries operated by Concawe members in Europe. Of course, SAF blending is another way to reduce these fuel properties which will occur naturally in line with ReFuelEU aviation, but this is well understood and not the focus of this study. The study also doesn’t specifically look at the production of imported product (around 40% of EU jet fuel).

The findings are enlightening, and highlight that it is no simple matter to reduce these properties in existing EU refineries, with real risks to European refining capacity and security of supply of this critical fuel for European civil and military aviation needs.

The study also investigates which other fuel properties are affected by hydroprocessing to reduce the aromatic, naphthalene and sulphur contents of jet fuel. Some fuel properties critical to engine operation and safety are affected, highlighting important considerations here. A literature review is offered, and a matrix of pilot samples were analysed to guide this discussion. This section is indicative of further fuel quality considerations required and is not intended to be a conclusive study of engine operability issues relating to any potential changes in fuel quality.