Pratt and Whitney says all aircraft engines could be powered by green energy by 2040

With jet fuel accounting for up to 40 per cent of an airline’s operating costs, research is powering ahead into hydrogen or electric-powered engines.

The future of aircraft engines is green, with the options expanding as technology advances. Graphic supplied by Pratt and Whitney.

By 2040, all aircraft could be powered by green energy such as hydrogen and electricity, as the aviation industry strives to reverse its image as an environmental vandal.

US engine manufacturer Pratt and Whitney has revealed the ambitious timeline for “sustainable aviation” and the steps being undertaken to achieve it.

Environmental targets and money are driving the research, with jet fuel accounting for up to 40 per cent of an airline’s operating costs.

Pratt and Whitney senior fellow for advanced technology, Michael Winter, said aircraft engines were already successfully using sustainable aviation fuels (SAF) made from things like plant matter, rubbish, sewage and algae.

But he said supply remained an issue, with 370 billion litres of jet fuel needed for the global aircraft fleet, and only a few hundred million litres of SAF being produced.

“Because of the supply issue, SAF tends to be two to five times more costly than jet fuel but as capacity increases that will decrease,” said Dr Winter.

“We’ve burned 100 per cent SAF in our engines for more than 15 years, and when there’s enough SAF for 100 per cent use we will be ready.”

Hydrogen-powered aircraft were also attracting much interest, particularly in Europe, where countries like England and France had committed significant funds towards research.

Dr Winter said hydrogen was likely to be in use from about 2035, for aircraft up to single body jets such as Boeing 737s and A320s.

But he said hydrogen was not without its challenges, due to the need to liquefy the gas in order to burn it.

“There’s a number of nuances with handling liquid hydrogen, including the fact it’s -253 degrees centigrade, so putting that on an aeroplane presents some challenges,” Dr Winter said.

Limitations also applied to electric-powered aircraft due to the density of the batteries, which were about “40 per cent worse than the density of jet fuels”.

“It’s not hopeless, and it’s got better over the last three decades, and there are studies looking at how quickly the battery density will improve,” said Dr Winter.

“We see the penetration (of batteries) happening in the smaller engine space, such as the regional turboprop because of the lower requirement of the total mass of battery on board.”

More realistic was the “hybrid” electric model, using a combination of battery power and sustainable aviation fuels to power aircraft.

As power sources changes, so too would the shape of aeroplanes, with Pratt and Whitney predicting a re-emergence of supersonic commercial aircraft in the next 20 years.

Already United Airlines has placed an order with Boom for its first supersonic jet powered by sustainable air fuel and expected to go into service in 2029.

“We do expect the next generation of aircraft to stick with the tube and wing configuration but probably not the generation after that,” Dr Winter said.

“We’ll see sort of blended wing, or hybrid wing body-type constructs that can operate more quietly and use the air moving up the surface of the fuselage.”

More than 100 commercial aircraft in Australia are powered by Pratt and Whitney engines, the newest of which is the GTF, used in the A320neo family.