It outlines three potential scenarios, forecasting the percentage of 2050 remaining emissions relative to 2005 levels.

The first “won’t happen” since failure to fully embrace SAF has already happened, it states.

The second could happen with hydrogen coming on stream quicker, thought Jet A (the most commonly used fuels, from a mix of hydrocarbons) will continue to fly people and keep emissions high.

This opens the door to hydrogen. “This paper has established already that from both technical and political points of view the industry can cut down its emissions by almost 96.81% compared to 2005 levels if hydrogen is given the respect it deserves by the big manufacturing companies, large airline operators and of course by politicians,” it finds.

“Enough technological advancements have been made in the hydrogen field to reassure us that it will play a huge role in aviation but how fast it will be im- plemented will finally dictate if it can ‘save’ the industry in time or not.”

SAFs challenges aren’t just producing volumes at scale but ensuring they can be produced sustainably, potentially an even bigger task.

If SAF can truly live up to its name, all this energy needs to come from renewable energy sources.

“Growing the crops for food and collecting their waste for SAF production will mean that all the agricultural practices involved will have to be sustainable (fertilisers, electricity, collection),” it notes.

“Additionally, transportation will have to be electrified in the form of fuel cell powered heavy-duty trucks to the degree that even the small oil tankers that are used to refuel the planes on the runway as people board them, will have to emit no carbon.”

With hydrogen, the paper highlights the proprietary design of Universal Hydrogen, which has been working on tanks that can store hydrogen both in gaseous and liquid forms, and ZeroAvia, which is developing H2-EI powertrains.

Such companies are “not reinventing the wheel” as they are not even designing complete aircraft – in a bid to circumvent design certification times.

Instead, they take existing airframes, like the popular short haul turboprop powered De Havilland Dash 8 (such as that pictured), which has a proven safety track record and retrofitting them with a new powertrain system made out of electric motors, fuel cells and power electronics.

“If the hydrogen used is produced with 100% renewable energy, then the ‘well-to-wake’ emissions will truly be zero,” it notes.

In a world dictated by stock prices, dividends and shareholder needs, the aviation industry needs to decide who it wants to please, it concludes.

“It’s not too late to turn its back on the poor decisions made so far, but as things stand, the skies are about to fall on its head.”