THE WORLD IS PRAYING FOR SAF. BUT WHICH SAF, MADE OF WHAT?

Here lies a challenge. The world uses around 300-350 million tonnes of jet fuel per year, 99.83% of it made from petroleum. The world needs urgent reduction of fossil emissions but currently has few options to produce a more sustainable replacement. The obvious choices are bioethanol, vegetable oils (including used cooking oil) and animal fat. The problem with these feedstocks is two-folded: 1) the yield per ha-year is low because photosynthesis’ light-to-biomass efficiency is around 1% for the best above de ground terrestrial plants and so vast areas are needed for dedicated crops; 2) these are food crops that yield sugar, starch, and edible oils that are just a fraction of the biomass above the ground. This means only 0.20% goes to biofuel in the best of all current processes that is ethanol from sugarcane. If the demand for SAF based on this food crops explodes, the search for new land to grow them will also explode producing huge amounts of land use change that can emit a lot of carbon along, putting immense pressure on the food supply, the food price and on the environment. As consequence, world leaders are already reacting. The EU has decided that SAF and Bio Bunker cannot come from food crops, only from lignocellulosic residues, used cooking oil and discarded animal waste. President Joe Biden’s administration is about to announce an adjustment to its scientific modeling for ethanol, probably showing its emission reduction power against gasoline is not as good as previously thought. Much probably the US and other players will follow on the footsteps of the EU, leaving e-fuel and other 2nd Generation biofuels as the only way out for SAF.