10th June 2025
Not only do fossil fuel companies promote their oil and gas as being cleaner on the basis of reduced scope 1 and 2 emissions, they also promote themselves as offering the consumer ‘low carbon products.’ For example this from Shell:-
“Shell Low Carbon Solutions offers products and solutions to help customers in heavy transport and industry reduce emissions and deliver more value. Learn about their low-carbon fuels, carbon credits, CCS, DAC, hydrogen, and how they work with partners in aviation…” (1)
But what are low-carbon fuels? For Shell, low carbon fuels include sustainable aviation fuel (SAF), biomethane which is also known as renewable natural gas (RNG) and renewable diesel known also as HVO and HEFA.
SAF is a biofuel meaning that it is produced from plant or animal based materials rather than from fossil fuels. SAF is designed to as a ‘drop in’ fuel for aviation is it can be sued in airplanes without any alteration to the plane’s fuel systems and engines. SAF is seen as low carbon because the carbon dioxide emitted in use is what would have been what as the plant/ animal material had absorbed in its life time. There is of course a carbon footprint in producing SAF which means it would cut emissions compared with tradition jet fuel by 80% rather than 100%.
However at the moment SAF only accounts for about 0.1% of total aviation fuel consumption. Whilst scaling up production facilities is part of the issue, the bigger issue is availability of plant and animal material from which to make SAF. The bio materials used including waste material from farms and forestry work, solid municipal/ household waste (including food waste and packaging), used cooking fat, animal fat, corn/soy/rapeseed/palm oil, sugar cane and beet, aide and other grains, grasses such as miscanthus, algae etc.(2) However the supply of such material is at present insufficient to match the demand for aviation fuel and this raises the conundrum that to supply enough plant and animal material, it would be necessary to set divert agricultural land away from growing food to growing aviation fuel.
The Royal Society has made estimates as to how much biomaterial would be needy to meet UK aviation fuel demand. “Used cooking oil in the UK can be utilised to provide 0.3 to 0.6% of the total amount of jet fuel required every year in the UK. The report also calculated that to meet the 12.3 million tonnes of jet fuel per year will require 42.4 million tonnes of rapeseed biomass per year and 68% of UK’s agricultural land. The report suggests that utilising Miscanthus for alcohol-to-jet in the UK will require 10.3 to 6.2 million hectares to meet UK fuel demand.” (3)
Clearly SAF is not in reality a sustainable option. If net zero is a real ambition, then reducing air miles will have to be a major part of the solution.
The Green Tau 