Is sustainable aviation fuel the solution for the aviation industry?

In a recent report by Rethink Energy, senior analyst Bogdan Avramuta points out that relying on “sustainable aviation fuel” – i.e. jet fuel created from waste – will not achieve the decarbonization goals of the aeronautical industry.

“The 2050 target the industry has set is to halve its emissions from 2005 levels.”

Sustainable Aviation Fuel (SAF) is a direct replacement for Aviation Fuel (Jet A). Think of garbage kerosene. There are nine ways to make SAF, most involving the use of some form of carbon-rich material waste – municipal solid waste, agricultural or forestry waste, cooking oils, animal fats, sugar cane, sugar beets sugar and plants high in saturated fats such as jatropha and camelina.

Sustainable aviation fuel from waste is a possible solution…in theory. “Reports that have examined the global potential of these biofuels indicate approximately 30 EJ – 1 exa-joule = 1 million terajoules – of annual feedstock value of which 43% is straw and 33% forest residues.

“Only about half of that (~15 EJ) would be needed to reach the 100 billion gallon goal, but setting up an industry that collects all of that, then transports it to chemical plants and oil refineries, just hasn’t happened far away, and with no real plan in place, that means no one is really serious about going this route.

“Which means the sustainable aviation fuel industry is just an excuse to keep doing what it’s been doing,” adds Peter White, principal analyst at Rethink Energy and founder of Rethink Research. As per usual.

In the end, planes running on SAF still emit the same amount of carbon dioxide. Given that Airbus and Boeing have predicted that the number of flights and the number of planes will double over the next 30 years, what is the answer? Can we turn to hydrogen or electric windows?

Rethink Energy sees 3 possible scenarios: 1. SAF, 2. More SAF and 3. Hydrogen.

Remaining shows.

The advantages of hydrogen are that “its mass energy density is three times greater than that of kerosene. The disadvantage is that its volumetric energy density is three times lower.

How do you store volume and manage the particular chemical attributes of hydrogen? Universal Hydrogen aims to have a pressurized tank available for commercial flights in the coming years. Rethink Energy projects that the cost of H2 will be reduced to $1.50 kg by 2030.

Due to the lower mass/energy density (approximately 0.936 MJ/kg or 260 Wh/kg), Rethink Energy expects battery-powered flight to be limited to very small aircraft. Other commentators have named a niche role for small electric planes like Alice to use on short city-to-city flights, much like an Uber for the family.

“There are currently two types of hydrogen aircraft under development: hydrogen electric (H2-El) and hydrogen internal combustion (H2-ICE). … If the hydrogen used is produced with 100% renewable energy, then the emissions “from the well to the awakening” will be truly nil.

Adapting existing engines and aircraft to run on hydrogen means these technologies will come to market faster.

The Zero Emission Aviation Alliance (AZEA) launched in the EU – and including hydrogen pioneers like ZeroAvia and Universal Hydrogen; air operators like EasyJet and WizzAir; engineering giants like Airbus, Rolls-Royce, GE and even Pratt & Whitney – are expected to accelerate the industry’s transition to zero-emission fuels. The EU is expected to introduce regulations to encourage this. A notable favorite is Denmark, which is gearing up for its first zero-emissions commercial flight as early as 2025 – powered by hydrogen fuel cells spinning electric motors.

SAF in the energy mix

Projections of the energy mix.

Rolls Royce, in partnership with Tecnam and Widerøe, plans to have a commercial aircraft in service by 2026. Airbus believes hydrogen is the fuel of the future and has joined the largest infrastructure investment fund in clean hydrogen in the world in 2022.

The majority of flights are less than 2000 km. It is expected that these routes can be served by hydrogen-powered turboprop aircraft. They could just be a bit slower. We have the technology, but the question now is how quickly it can be implemented.

“In a world dictated by stock prices, dividends and shareholder needs, the aviation industry must decide who it wants to please. It’s not too late to turn his back on the bad decisions made so far, but as things stand, the sky is about to fall on his head.

The sky is falling for those who choose profit over the planet.


Do you appreciate CleanTechnica’s originality and cleantech news coverage? Consider becoming a CleanTechnica Member, Supporter, Technician, or Ambassador – or a patron on Patreon.

Don’t want to miss a cleantech story? Sign up to receive daily updates from CleanTechnica via email. Or follow us on Google News!

Have a tip for CleanTechnica, want to advertise or suggest a guest for our CleanTech Talk podcast? Contact us here.