Climate scientists claim that while sustainable aviation fuels (SAFs) will play a useful role in the future of aviation, the industry’s growth plans, with its heavy emphasis on SAFs to replace fossil fuel, are “unrealistic and irresponsible”.
This is according to an article in The Conversation, by scientists Susanne Becken and Brendan Mackey, both from Griffith University, and David Simon Lee, Manchester Metropolitan University, drawing on their own paper, published in sciencedirect.com .
SAFs are the airlines’ preferred industry solution as they will allow long-haul flights to take place. Iata says SAFs could contribute around 65% of the reduction in emissions needed by the industry by 2050.
SAFs are produced from food waste such as cooking oil or animal fat. Energy crops (such as soy and willow), agricultural residues (husks, bagasse), and forest biomass (such as logging residue and manufacturing waste) provide larger volumes of raw materials, but chemical engineering processes to turn them into fuel are still developing, say the climate scientists.
They say one of the problems is the huge amount of biomass and clean energy needed. Producing sustainable aviation fuels would require about 9% of global renewable electricity and 30% of available biomass in 2050, and that’s if 70% of fuel used by airlines in 2050 is biofuel.
Iata acknowledges that the use of SAFs will require a massive increase in production in order to meet demand. “Iata encourages (governmental) policies which are harmonised across countries and industries, while being technology and feedstock agnostic. Incentives should be used to accelerate SAF deployment,” says Iata.
But there are several reasons why SAFs might not be the hoped-for silver bullet.
*The scientists say there is just not sufficient arable land on earth to produce enough plant material to make enough SAF to allow for the growth envisaged by the airline industry.
* Not only that, but using all that land to grow biomass for SAFs would compete with using that land for nature-based carbon removal, clean energy that could more effectively decarbonise other sectors, and captured CO2 to be stored permanently. That’s not to mention the displacement of other industries that already use significant tracts of land for production.
*The production of SAFs creates its own greenhouse gas emissions. Growing bio-crops, for instance, requires the use of emissions-intensive fertiliser, harvest machinery and transport.
*The scientists claim too that vast tracts of rainforest are already being razed to make way for crops used in biofuels, and that SAFs produced this way could ultimately be even worse for the climate than fossil fuels.
* “Finally, carbon dioxide is not the only aviation emission that contributes to climate change. Others include nitrogen oxides, water vapour and soot. Research to date is inconclusive about whether sustainable aviation fuels will improve this problem,” say the scientists.
The three scientists believe that more private and government investment should move towards lower-carbon forms of transport, such as rail. “And a public shift in mindset is required, involving how often and how far we need to travel.
“Airlines must not take more than their fair share of finite resources to claim the label of ‘sustainable’,” they say.
