Is it possible to feed airplanes with fat and sugar?

Using clean jet fuel would require enormous acres of land.

When the politician next to him pulled out his phone to take a selfie, Virgin Atlantic CEO Richard Branson looked into the camera, smiled and gave two thumbs up. The world's first commercial airliner to cross the Atlantic Ocean using 100% biofuel has just landed in New York.

Virgin Atlantic's Boeing 787 runs not on fossil fuels but on leftover plant sugars and fats, a form known as sustainable aviation fuel (SAF).

The British Conservative MP posted a smiling selfie with Branson on the social network X, formerly known as Twitter, and called the flight "a significant achievement for British aviation". (The trip was partly funded by the British government.)

However, not everyone is sure that this is the future of aviation. The biomass needed to produce biofuels can come from various sources: plant materials, food waste and even algae. Although biofuel releases CO2 when burned, some consider it an environmentally friendly option because it is renewable and biomass captures some CO2 from the atmosphere as it is developed.


The problem is the large amount of biomass necessary to feed the large sector of the aviation industry with this fuel.

A research paper published in August estimated that if sugar cane were grown and used to produce biofuel for commercial aircraft, it would require 125 million hectares (482.000 square miles) of land, roughly the same area as the states of California, Oregon , Washington, Nevada and Louisiana together. It's a lot of land. And if you tried to use only biomass waste, you wouldn't have enough waste to keep all the planes in the world flying, some experts say.

The aviation industry currently accounts for about 3,5% of greenhouse gas emissions, almost equal to all the emissions of Japan, one of the world's largest emitters.

SAF advocates say the fuel could make flying much greener than it is today. The reality is that increasing SAF production is a monumental task.

David Lee, a professor of atmospheric sciences at Manchester Metropolitan University who studies the environmental impact of aviation and co-author of the paper that investigated the feasibility of the transition to SAF, commented on the matter: "What they did was important, but they simply demonstrated that flying is safe and there are no problems with that fuel".

According to Lee, by switching to SAF fuel instead of fossil fuels, carbon savings of around 70% can be achieved, although this depends on the specific biomass source chosen.

Lee notes that international regulations do not currently allow flights to use more than 50% SAF as fuel, so Virgin Atlantic's jump across the pond required special permission from the UK Civil Aviation Authority.

All of this constitutes a successful proof of concept. But nowadays it is difficult to have more than one great flight with 100% SAF.
"You just can't get those damn things," Lee said. "If we want to test engines, we have difficulties buying fuel". This is a problem that Virgin Atlantic itself recognizes.

SAF represents only 0,1% of the total aviation fuel used. The International Air Transport Association predicts that the aviation industry will need 450 billion liters of SAF by 2050 (only 300 million liters will be produced in 2022).

However, to date, SAF has helped power hundreds of thousands of flights, at least as part of a mix with fossil fuels. US SAF production is estimated to reach 2,1 billion gallons (7,9 billion liters) per year by 2030, well below President Biden's goal of producing 3 billion gallons (11,3 billion liters) of fuel for that year.

Increasing SAF production for aircraft is difficult

In a Royal Society report published earlier this year, Lee and his colleagues examined the UK's potential to produce its own SAF for commercial airlines. "We came to the conclusion that there really is a shortage of land", he claimed.

There is fierce competition for land around the world. Consulting firm McKinsey & Company estimates that by 2030 we will need an additional 70 to 80 million hectares of arable land worldwide, an area larger than the state of Texas.

Most of this new arable land (70%) is needed to grow food to feed livestock. In McKinsey's scenario, only 10% of the total area needed would be dedicated to biofuel production.

Some SAF come from waste fats, for example during food production. In theory, relying on these sources could reduce the need to grow crops solely for biofuel production. But there is very little waste, says Hannah Daly of University College Cork in Ireland. Even if all the biomass waste available in the Republic of Ireland were combined, she said, they could only replace about 4% of the country's fossil fuel use. According to him, the calculations will be similar in other countries.

What if you think you're buying waste fats when you're not?

"There is a significant risk that this 'used cooking oil' could be fraudulently rebranded as virgin palm oil." Daly said. "This could contribute to deforestation."

Some SAF alternatives, including hydrogen fueling and electrification, are not currently viable options for large commercial flights.

Chelsea Baldino, senior researcher at the International Council on Clean Transportation, and her colleagues estimate that waste-based SAF in the United Kingdom could meet up to 15% of that country's jet fuel needs by next year 2030.

The ICCT estimates that the United States will likely produce only 3,3 to 4,2 billion gallons of SAF in 2030, while U.S. airlines consumed 23 billion gallons of jet fuel in 2019.

"Air shipments are the most efficient if you need your cargo or documents to arrive quickly and securely. biofuels that significantly reduce the greenhouse gases needed to decarbonize jet fuel will not be available on a large scaleBaldino said that e-fuels, synthetic versions of fossil fuels produced from renewable energy sources, will be “essential.” It takes a lot of energy to produce e-fuels, but their advantage is that they do not release additional carbon to the atmosphere, as occurs with newly extracted fossil fuels.

Josh Moos, an economist at Leeds Beckett University in the UK, criticized Virgin Atlantic's 100% SAF flights as "fake ecology"Science shows there is no such thing as sustainable aviation," he said. He said it would be better to reduce demand for flights around the world, perhaps by introducing a tax on frequent flyers or increasing taxes on the airline industry. Moos admits that these types of measures are "politically and socially unacceptable", although both he and Daly maintain that they may be necessary if we are to achieve our NetZero goals.

A Virgin Atlantic spokesperson said: “We are committed to achieving net zero emissions by 2050 and have set key milestones to achieve this, including: 10% clean aviation fuel by 2030"

He noted that the SAF flight from London to New York was 100% based on residual biomass and that the demonstration was "an important step, but not the final goal" in the company's efforts to expand the use of SAF in the coming years.

Some skeptics remain unconvinced. For example, Daly notes that if SAF were to substitute aviation for an increasing proportion of fossil fuels, the overall benefits could be overshadowed by a rapidly growing aviation industry.

Eurocontrol, the European aviation safety agency, predicts that the total number of annual flights worldwide will reach 16 million in 2050, an increase of 44% compared to 2019.

"I want to fly without feeling guilty, but that's impossible"Daly said.

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