Aircraft makers turning green
ALL aircraft could be powered by green energy such as hydrogen and electricity by 2040 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 that.
Environmental targets and money were 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 already aircraft engines were successfully using sustainable aviation fuels (SAF) made from things such as 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 including 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, including the need to liquefy the gas to burn it.
“There’s a number of nuances with handling liquid hydrogen, including the fact it’s -253C, 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 change, so too would the shape of aeroplanes with Pratt and Whitney predicting a re-emergence of supersonic commercial aircraft in the next 20 years.
“We do expect the next generation of aircraft to stick with the tube and wing configuration but probably not the generation after that,” he 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.”