The fat of dead pigs, cattle and chickens is being used to make greener jet fuel, but a new study warns it will end up being worse for the planet.
Animal fats are considered waste, so aviation fuel made from them has a lower carbon footprint than fossil-based kerosene. Airlines are under pressure to rein in their huge carbon emissions, which mainly come from burning kerosene in aircraft engines.
Demand for fuel made from animal by-products is expected to triple by 2030, with airlines leading the charge to reduce their emissions. The UK and EU governments are putting in place challenging mandates that will require airlines to use a bigger proportion of sustainable aviation fuel (SAF) in their tanks.
But there is not enough supply of animal fats to meet the growing demand from aviation, as they are already used in other sectors such as cosmetics and biodiesel. A transatlantic flight between Paris and New York would need the fat from 8,800 dead pigs each way, according to calculations by Transport & Environment (T&E), a clean transport campaign group.
Other sectors that currently use animal fats may switch to palm oil, which is a major source of deforestation and greenhouse gas emissions, if aviation consumes more animal fats. The increased use of palm oil is linked to rising emissions as older forests which store vast amounts of carbon are cleared for new plantations.
“This is the worst environmental outcome possible. If virgin palm oil were to substitute animal fats, CO2 emissions of animal fats biofuels could be up to 1.7 times worse than conventional diesel,” said Matt Finch from T&E.
“There’s not a never ending supply of animals, or animal fat. So if you put on a massive extra demand source from anywhere from aviation, in this case, the industries where fat is currently being used, will have to look for alternatives. And that alternative is palm oil. So aviation indirectly, will be responsible for increasing the amount of palm oil being pulled through the European systems,” he added.
The UK and EU have different policies on SAF, with the UK likely to limit or ban the use of animal fats, while the EU allows potentially unlimited amount of them. T&E argues that both regions should focus on developing SAF from other sources, such as algae and waste wood, which have lower environmental impacts and higher potential.
However, these sources also face challenges such as scalability, cost and competition with other uses. T&E says that SAF alone will not be enough to decarbonise aviation, and calls for measures such as taxing kerosene, improving aircraft efficiency and reducing demand for flying.
– Using pig fat as green jet fuel will hurt planet, experts warn, BBC, May 30, 2023
– Animal fat jet fuel demand risks palm oil surge, worsening emissions, Thaiger, May 31, 2023
– Use of animal fats to produce jet biofuels may impact planet, warns new study, Interesting Engineering, May 31, 2023
– Animal fat use in green jet fuel soaring and could be worse than kerosene, study warns, Sky News, May 31, 2023