IEA Bioenergy | Task 39: Progress in Commercialisation of Biojet / Sustainable Aviation Fuels (SAF) - Technologies and policies | 2024

IEA Bioenergy Task 39  released a report on the progress in commercialisation of Biojet or Sustainable Aviation Fuels (SAF) focusing on the developments in technologies and policies. With an international commitment from the aviation sector to reach net zero by 2050, a myriad of measures is required to reach that target including new technologies, improved operations, sustainable aviation fuels, carbon offset. According to the Air Transport Association (IATA), the large majority of emission reduction must come from the use of sustainable aviation fuels. Additionally, the non-CO2 impacts of aviation are also gaining attention, for instance the aromatic content of jet fuels which contribute to the non-CO2 effects.

Since IEA Bioenergy’s last report, it is reported that the production of SAF has increased as more SAF projects have come to light. This is also due to the SAF specific policies that have been brought forward for instance in the EU with ReFuelEU Aviation mandate and in the USA with the Inflation Reduction Act.. In addition, there has been progress in the commercialisation of the technologies and more investments in research and development.

Nevertheless, there are still some challenges that are faced regarding the conversion pathways that need to be addressed. In the meantime, the lipid-derived HEFA pathways is the main one supplying the majority of SAF volumes. However, other technologies, such as gasification with Fischer Tropsch and Alcohol-to-Jet are nearing commercial status.

The report focuses on the progress of the technologies, key developments in commercialisation and recent research-and-development trends. Below is an overview of the trends and challenges in SAF technologies addressed in the report:

 

Lipid derived HEFA pathway

HEFA pathway has been primarily used for the production of renewable diesel. However, a large number of new facilities using this technology have targeted the production of SAF. Developments of new catalysts that can increase SAF fraction and minimise loss of yield has been reported.

Gasification based technologies for SAF production

Gasification of biomass produces syngas which finds uses in several pathways to produce SAF through different routes for instance via Fischer Tropsch synthesis or via methanol intermediate and methanol-to-jet conversion. Alternatively, syngas can be fermented to ethanol, with the alcohols converted into SAF via the Alcohol-to-Jet pathway. Several projects using these pathways have been announced. A challenge remains regarding clean up of the syngas. Although multiple biomass feedstocks can be used by gasification-based technologies (e.g municipal solid waste, forest,and agricultural residues), the supply chain for these feedstock types are not well established.

Alcohol to Jet pathway for SAF production

Facilities using this technology have been planned and one (Lanzajet’s Freedom Pinesfacility) is expected to be commissioned by 2024. Various types of alcohols can be used in this process, with ethanol and isobutanol already approved under ASTM D7566. Methanol to jet pathways is on its way to getting ASTM approved. A challenge remains regarding the cost of the ethanol and therefore cost of SAF, in the case of cellulosic ethanol via gas fermentation and alternative pathways.

 

Powerto Liquids (PtL) pathway for SAF production

While the Power to Liquids pathway can achieve low carbon intensity SAF, this will b ehighly dependent on the source of electricity used for hydrogen production and the source of CO2. The high cost of production for PtL pathways will also present a major challenge. The power to liquid pathway can use a Fischer Tropsch synthesis to produce hydrocarbons or methanol and converted into SAF via Alcohol to Jet pathway. Substantial technology developments are still needed for the PtL pathway to achieve commercial status.

 

Co-processingto provide lower carbon intensive CI jet fuels

Refinery co-processing is based on the insertion of 5% lipids in the hydrotreater, as this is the maximum fraction allowed by ASTM D1655. During 2022/23, about six refineries in Europe started producing lower carbon-intensive jet fuels through co-processing, and further plans for refinery co-processing (to produce lower CI fuels) were announced by another seven refineries.

Direct thermochemical liquefaction pathways for SAF production

Production of SAF via a bio-oil/biocrude intermediate has been challenging and is at a lower development stage than other pathways. Projects in the EU and US continue to explore the usage of sewage sludge and hydrothermal liquefaction as a pathway for SAF production, but this is still at a low TRL level.

 

Read the full report by downloading it here.