Today’s conventional wisdom around the Sustainable Aviation Fuel (SAF) market is that it will start with the HEFA pathway which converts oily waste compounds into jet fuel. The process is well established and economical. The challenge is aggregation of the feedstocks which takes the form either of used cooking oil and oily waste streams coming out of some vegetable oil production streams. They could also take virgin vegetable oil and oil from oilseeds to produce (but these tend to have a higher lifecycle emission associated with them as they are cultivated and will require fertiliser inputs and other resources).
The regulators and market expect that these feedstocks will be insufficient as the virgin oils should be reserved for food use and the waste-based feedstocks are limited. So then when the HEFA feedstocks supply goes down, prices of these feedstocks would move up towards the next SAF pathway. The popular contender after HEFA is the alcohol-to-jet (ATJ) pathway. They take bioethanol or methanol and turn them into jet fuel. This process is a bit more expensive, but because bioethanol is already being produced by various plants worldwide to supply provide for gasoline blending in countries with ethanol-blending mandate, it has a much more stable and ready market than used cooking oil.
Further technology pathways are expected to involve gasification where biomass is subjected to thermal processes that breaks down the material into constituent carbon, oxygen, hydrogen and nitrogen compounds, then reformed to make liquid fuels including jet fuel. These pathways are even more expensive, but their feedstock, which is pretty much any biomass, would be much more abundant.
So, the supply curve is expected to notch upward in discrete steps; once prices hit the threshold to unlock the next technology pathway, more feedstock will enter the picture and hence increase the supply of SAF available. This doesn’t mean that the earlier pathways will earn more margin, because the bottlenecks are the feedstocks; typically, the feedstock owners or aggregators tend to extract more of that value.
But this would mean that the prices of SAF should and can only rise as the mandate for more SAF and aviation decarbonisation becomes stricter and emission reduction targets become more ambitious. Now there is another transition to consider. That is a scenario where the chief driver of SAF adoption, regulations and blending would be decided by the market – but the outcome they are targeting would be based on proportion reduction of carbon emissions relative to conventional jet fuels.
Now of course, some from Oil & Gas players might think they can use carbon capture and storage to lower the fossil jet fuel intensity to meet the criteria. Yes to a certain limit; because the carbon dioxide emitted during the aircrafts’ journeys from fossil jet fuels will always been counted while the biofuel or synthetic fuel’s emissions will be zero (because they are short-cycle or biogenic carbon dioxide).
So I urge regulators and policy-makers; focus on the carbon intensity reduction targets, rather than volumetric blending targets.