A commercial plane takes off after sunset from Geneva Airport, Switzerland.
FABRICE COFFRINI | AFP | Getty Images
From the Wright brothers’ historic flight in 1903 to the development of supersonic aircraft, the history of aviation has been driven by technology and ambition.
Now, as the 21st century progresses, the sector continues to show its appetite for innovation and radical design.
Last September, for instance, a hydrogen fuel-cell plane capable of carrying passengers took to the skies over England for its maiden flight.
More recently, United Airlines announced it had signed a commercial agreement to purchase aircraft from a firm called Boom Supersonic.
In a statement, United said the Overture aircraft — which is yet to be built — was set to be “optimized to run on 100% sustainable aviation fuel.”
All of the above are linked by a focus on technologies designed to reduce aviation’s environmental footprint. This represents a major task, even if the number of flights last year slumped due to the coronavirus pandemic.
According to the International Energy Agency, carbon dioxide emissions from aviation “have risen rapidly over the past two decades,” hitting almost 1 gigatonne in 2019. This, it notes, equates to “about 2.8% of global CO2 emissions from fossil fuel combustion.”
Elsewhere, the World Wildlife Fund describes aviation as “one of the fastest-growing sources of the greenhouse gas emissions driving global climate change.” It adds that air travel is “currently the most carbon intensive activity an individual can make.”
A variety of solutions
Iain Gray is director of aerospace at the U.K.’s Cranfield University. In a phone interview with CNBC, he described zero carbon as “the top priority” for the industry and sought to emphasize the importance of developing a range of solutions to tackle the challenge.
“The really big technology driver is around the propulsion system,” he explained, “but that doesn’t take away from the importance of new technologies around … new lightweight materials, enhanced carbon composite materials, and the systems itself.”
Expanding on his point, Gray provided an example of why the innovations on planes flying above our heads should not be viewed in isolation.
“There’s a lot of effort goes into reducing the weight on an aeroplane for it only to spend half an hour circling an airport,” he said.
“So the whole interaction of air traffic management with the aircraft itself is a … very important development and new technologies on airspace management are emerging all the time.”
The power of propulsion
Alongside the development of hydrogen fuel-cell planes there’s also been a lot of discussion around electric propulsion in recent years, with firms such as Volocopter and Lilium developing eVTOL, or electric vertical take-off and landing aircraft.
The key with technologies such as these is the types of journeys to which they can be applied.
“If you look at hydrogen fuel cells and you look at batteries, that really is very much aimed at the smaller aircraft, that’s the sub 1,000 kilometer range,” Cranfield’s Iain Gray said.
“You have to do that in a zero carbon way, there’s no question,” he added. “Is that going to make a big difference to the overall CO2 contributions that aviation makes? No.”
“We need to focus on the longer range flights, flights greater than 1,000 kilometers, flights greater than 3,000 kilometers in particular.”
This focus on long-haul trips will be important in the years ahead, even though they make up a small proportion of flights.
According to a sustainability briefing from Eurocontrol published earlier this year, “some 6% of flights from European airports were long-haul” in 2020, measuring over 4,000 kilometers (around 2,485 miles) in length.
The intergovernmental organization went on to state that “more than half of European aviation’s CO2 emissions were from this tiny proportion of the overall number of flights.”
This viewpoint was echoed by Jo Dardenne, aviation manager at Transport & Environment, a campaign group headquartered in Brussels.
“We shouldn’t forget that the biggest chunk of aviation emissions are linked to long haul flights because you fly longer, you fly higher,” she told CNBC.
“So all in all you’re producing more CO2 … those long haul flights can only be decarbonized by replacing the kerosene that they’re using.”
It’s on these longer journeys that sustainable aviation fuel could have a significant role to play in the future.
Although the European Union Aviation Safety Agency says there’s “not a single internationally agreed…