Hydro-processed esters and fatty acids (HEFA)
To produce biofuels on the basis of hydro-processed esters and fatty acids (HEFA), any form of native fat or oil can be used. Apart from waste fats – left over from the food industry – vegetable oils and fatty acids from oil and fat refining processes are the most common forms used.
In the first stage of production, the oils and fats are hydrogenated and in the second stage, they are refined, in a very similar process as is used with fossil fuels. The relevant production process is already fully developed and has been certified by the international standardisation organisation ASTM since 2011. Even today, increased amounts of HEFA jet fuel are already being used for testing purposes in scheduled passenger flights. Therefore, the production of biojet on a HEFA basis is rated at 9 on the FRL scale.
Nevertheless, the expansion of production capacity is progressing too slowly. There are currently only four large-scale biorefineries in the world that specialise in the production of certified fuels from vegetable oil – including alternative aviation fuel.