SAF Enilive: the biojet fuel for a more sustainable aviation

SAF (Sustainable Aviation Fuel) is a biofuel produced using the HEFA technology (via the hydrogenation of esters and fatty acids) and can be blended with conventional aviation fuel in proportions of up to 50%. It is made 100% from renewable raw materials, primarily waste and residues such as used cooking oils, animal fat and by-products from vegetable oil processing.

Unlike fossil-based products, biofuels are derived from biogenic raw materials and therefore enable a reduction in GHG emissions, calculated across the entire value chain. Currently, SAFs are the only available solution to contribute to the decarbonization of air transport. Biofuels do not require modifications to aircraft or to the existing fuel distribution infrastructure at airports.

To achieve the goal of more sustainable air transport, SAF producers work in synergy with airlines, engine manufacturers, airport operators and institutions.

At European level, Regulation (EU) 2023/2405 has established that aviation fuel suppliers must ensure increasing shares of SAF in the jet fuel made available to aircraft operators at every airport in the European Union. This model has led to the superseding of mandatory schemes introduced by some member states prior to the regulation’s adoption, thus eliminating any form of differentiation within a Union-wide market.

In Enilive biorefineries, biofuels (such as SAF and HVO diesel) are produced by subjecting raw materials to a series of physical and chemical processes. Waste, residues and vegetable oils arrive at the biorefineries via ships and tankers and are stored in tanks before undergoing two treatments: a physical one to remove impurities and a chemical one that leads to their actual conversion into biofuels.

During the first (physical) treatment, components critical to the Ecofining™ section, a technology developed by Eni in collaboration with Honeywell UOP, are removed from the bio-feedstocks. In particular, solid residues and gums (phospholipids) are eliminated through oil washing and centrifugation processes in the degumming section, while metals are subsequently removed in the bleaching section via an adsorption system based on specific materials (bleaching earths).

The resulting oil, free of metals, gums and solid residues, then passes to the second (chemical) treatment: Ecofining™. This process consists of two stages: hydrodeoxygenation, which eliminates oxygen and residual impurities (including nitrogen), and isomerisation, which transforms n-paraffins into isoparaffins with suitable cold flow properties.

The oils fed into the bio-refineries are primarily composed of triglycerides and fatty acids which, through these two stages, are transformed into hydrocarbons (isoparaffins), giving the product characteristics that are entirely similar to those of fossil diesel. Thanks to hydrogenation, total oxygen removal is achieved; its presence in products of biogenic origin would promote the formation of bacterial colonies and slime. HVO (Hydrotreated Vegetable Oil) diesel is therefore free from these issues and can also be used in its pure form in diesel engines.

Since the end of 2024, through the implementation of suitable plant modifications, specifically to the isomerisation unit, the tank farm and the logistics facilities, the Gela biorefinery has integrated the production of SAF alongside HVO diesel, bio-naphtha and bio-LPG. Furthermore, in 2026, the production of sustainable aviation fuels will also be extended to the Venice bio-refinery, thanks to a targeted investment plan.