07 July 2022
The new air travel technologies taking flight
Aviation accounts for about 2.5 per cent of global emissions – a lot less than people might first assume. But according to a recent article in the New York Times, that percentage could triple by 2050 if the industry keeps growing at its current rate without making any attempt to curtail its carbon footprint.
Even though COVID likely reduced carbon emissions by several hundred tons in 2020, it’s surely only a matter of time until air travel goes back to pre-pandemic levels and eventually exceeds them.
The UN set the industry a net zero target by 2050, and in October of last year, most major airlines signed up to that target.
So, what have these companies got going on in the pipeline to make good on their promise?
Electric tech transforming the domestic scene
The electric aircraft revolution is well underway. More than 200 global companies are developing electric concepts, with several them already completing successful test flights. However, there is a limit to the distances these planes can travel, and it comes down to the weight of the batteries.
Venkat Viswanathan, a Carnegie Mellon University mechanical engineering professor and aviation battery expert says: “You probably need like three, four times the weight of the airliner [in batteries] to be able to power that, which is why you can’t make them.”
However lightweight batteries can generate more than enough power to run smaller aircrafts for shorter, domestic journeys. From an emission standpoint, this is a monumental breakthrough, as about half of the flights routes worldwide cover less than 500 miles.
United Airlines’ 19 seat planes from Heart Aerospace are due to take flight in 2026, with short-haul domestic flights going out from Chicago and San Francisco. Mesa Airlines and Finland’s Finnair have also invested in Heart’s ES-19s.
Wright Electric is working on the largest electric plane to date – the 186-seat Wright 1 – and EasyJet is hopeful of taking it to the commercial market by 2030. Wright is also working on the 100-seater Wright Spirit, where it’s retrofitting BAe planes from aerospace company BAE Systems.
Wright say it’s much easier to tick off regulatory standards this way, potentially reducing federal certification by half the time. The time it takes for regulatory bodies to sign off these new technologies can take several years, so any way that can safely fast track that process is good news for the industry’s map to net-zero.
Hydrogen and electricity combine to take us further
Going long haul isn’t coming any time soon on electric only, though, which is why the industry is just as invested in finding a hydrogen-powered concept, or a hybrid that combines elements of both.
Encouragingly, we’re way past the ‘proof of concept’ phase. Many manufacturers and start-ups now have aircraft and engines in development and are actively testing. Boeing flew the first single-seater, hydrogen-powered plane in Madrid in 2008. And in 2016, German research agency DLR, the University of Ulm and a company called H2FLY, flight tested the first four-seater hydrogen plane in Stuttgart Airport.
Now the challenge is to bring a commercial plane into the picture. A project called HEAVEN is developing a powertrain to turn a propeller at high-speed using electric power, while experimenting with similar liquid hydrogen storage systems to those used in cars.
The powertrain turns hydrogen into torque, which then turns the propeller. HEAVEN report that it’s very efficient and quiet to run, producing a similar noise to the engine of a standard car.
If all goes to plan, the plane is scheduled to test sometime in 2022. HEAVEN is also doing a lot of supporting research to keep track of how economically viable these projects are, while running safety tests and simulations – all key metrics and processes to help fast track these technologies into our daily lives.
Hydrogen-powered turbines could be the long-haul answer
But to get to a future where hydrogen-powered planes can really start to cover long distances, turbines will have to play a part in the story. Again, work is well underway to reach that goal. Airbus revealed three different concept hydrogen planes in 2020, with plans to have them in service by 2035.
The first in the series will use a turbofan design. Airbus predicts it will be able to fly across continents, carry 120-200 passengers, and reach a range of 2,000+ nautical miles. It’ll be powered by a modified gas-turbine engine running on hydrogen through combustion.
Their second concept is a turboprop design, carrying up to 100 passengers. It’s a concept that will use a turboprop engine instead of a turbofan but will be powered by the same turbine technology. Airbus expects it to reach up to 1,000 nautical miles, making it ideal for short-haul flights.
And finally, they’re developing a ‘blended-wing body’ design, which will carry up to 200 passengers and reach similar distances to the turbofan model. The wings will merge with the main body of the aircraft and create a larger-than-usual fuselage, allowing Airbus to experiment with how they store and distribute hydrogen fuel.
Finding fuel space
Fuel storage has been one of the biggest obstacles stopping hydrogen concepts getting off the ground. Although lighter than kerosene, liquid hydrogen needs four times as much volume on board to pack the same punch.
FlyZero is another ground-breaking joint initiative in the UK, which has looked at 27 different ways of solving the storage conundrum. Led by the UK’s Aerospace Technology Institute (ATI) it brings together over 100 experts from multiple companies, including GE Aviation, Rolls Royce, and Spirit AeroSystems.
They looked at concepts with two fuselages (one for passengers and one for fuel), gondola designs, and even putting fuel tanks above where the passengers would sit.
David Debney, chief engineer at FlyZero comments on the struggle to find a solution that would pass through current regulatory standards: “We looked at wacky ideas, for example, where you could put a giant hydrogen tank between the wings and have two cabins, one at the back, one at the front, but they’d be separate. And you couldn’t get from one to the other. That’s not allowed under the regulations.”
Like Airbus, FlyZero announced three final concepts at the beginning of the year – one being a mid-sized aircraft, which they predict could fly non-stop from London to San Francisco.
Safety versus innovation
New innovations inevitably bring new risks for the industry to consider, and hydrogen-powered aircraft are no different. Thankfully, the global industry has been working with hydrogen for decades now – oil refineries and fertilizer producers, for example, have been working with the gas for over 40 years, so the safety standards and regulatory bodies relating to its use are well established.
It’s now just a case of making sure the aerospace industry doesn’t lose sight of the chemical it’s working with. Hydrogen is highly flammable and takes very little energy to ignite, so every element of these aircrafts needs to go through robust safety protocols. That’s everything from new composite engines to battery combustion, to fuel lines, right down to storing the chemical and transferring it across airports. .
However, time is also against us – the industry has UN targets to meet, but outdated safety frameworks could stand in the way of fulfilling them. In an interview with the BBC, Arlette van der Veer, senior manager of radical innovation at KLM Royal Dutch Airlines said just that: “Safety is the sole purpose of everything we do… but what I discovered in my research is that there are some mindsets and approaches from the 1960s or 1970s that still prevail today despite all the new testing methods.
"If I designed the most perfect aircraft… but there is no fuselage, it’s not cylindrical, it would be a case of the computer says 'no'. The certification authorities need to develop certification methods for aircraft designs that they have never seen before."
So, while safety should always be front of mind, regulators can’t always rely on the current safety standards to judge these new designs – there must be an ongoing effort by the industry to continually review their safety frameworks, and make sure they’re just as forward thinking as the innovations they’re considering.
Sky Breathe estimate that in 2019 they reduced CO2 emissions by
AI transforming efficiency and reducing emissions
There are other technologies that are helping companies save on emissions right now. Airlines are drawing on AI to make their jet fuel consumption more efficient. Air France, Norwegian, DHL, Oman Air and Aerolineas Argentinas, amongst many others, have all invested in Sky Breathe – a technology that pulls on big data and AI to analyse flight records and find smarter routes to save on fuel.
Sky Breathe estimate that in 2019 they saved their customers about 190,000 tons of fuel and reduced CO2 emissions by 590,000 tons. To put that in tangible terms, that’s the equivalent of the carbon captured by just under 10m trees over a ten-year period.
US Federal Aviation Administration (FAA) is also upgrading its system in a project called Next Gen to improve air traffic control operates. It will help schedule tighter landings and take offs, and decrease delays where planes circle airports or sit on the tarmac for too long.
Curtailing contrails would be a big industry win
Contrails - the condensation clouds that form at the back of a plane’s engine - produce a mix of water vapor, aerosols, and nitrogen oxides, which absorb more energy than they send back into the atmosphere. An EU commission found these can potentially be three times as damaging than CO2 alone.
But they only form in narrow channels in the atmosphere where the weather reaches the right level of cold and humidity.
So, if airlines could avoid these pockets, it would radically reduce their collective carbon footprint. A Japanese research paper found that changing routes could reduce the impact of contrails by 59%.
It’s normally just a case of shifting flight paths 2,000 feet up or down. And even though that deviation can affect efficiency and require more fuel, it wouldn’t be nearly as costly as the impact that contrails can cause.
However, these channels change from day to day and pilots need accurate reports to help them pre-empt when they should change path. The industry is currently working towards a future where pilots can report contrails in real time, just like they do with patches of turbulence.
Still work to do and investment needed
The industry is really making headway in its net zero mission, and we’ve only just scratched the surface of the projects out there driving the industry towards its renewable future.
But it’s an industry that’s still in recovery mode from the past two years. The pandemic has put a huge financial dent in its economy and it’s going to take some time for airlines and subsidiary companies to bounce back. Which means urgent projects like the ones mentioned in this article could fall behind in their projected time frame.
Given the above and the near-term need for emissions reduction, the short-term emphasis is therefore likely fall on other solutions such as sustainable aviation fuel (SAF) as the most direct way to make substantial reductions in net carbon emissions, with projects involving hydrogen and electric seen as a more long-term solution.
Regardless, to maintain momentum and stay on track with UN net zero targets, the industry needs investment, otherwise the progress up to this point could all be in vain.
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