A breath of fresh aircraft

More disruptive: Airbus’ blended wing body design allows the company to study a completely different configuration for hydrogen storage and propulsion. Picture: Airbus.

The aviation industry was the first in the world to make a long-term collective commitment to reduce its carbon footprint.

It is investing heavily in research and innovation to find new, lighter, materials, more appropriate engine architecture, and biofuels.

In September last year, the Air Transport Action Group (ATAG), an independent coalition of member organisations and companies throughout the global air transport industry, announced its roadmap enabling the industry to cut its CO2 emissions in half by 2050.

With the support of governments, the energy sector and researchers believe they can achieve the zero emission target by 2060-65.

To achieve the goal, it is clear that regulations, infrastructure and the logistics sector will have to keep pace with technological innovation.

Partners and subcontractors are unanimous – the entire aviation ecosystem must work together in a coherent approach to meet the challenges, underpin the constraints and build a low-carbon aircraft that guarantees safety, performance, and long-term competitiveness.

With innovation and excellence an historic part of the aviation industry’s DNA, there is considerable hope of having both economical and sustainable flights in the next decades.

Aircraft and engine manufacturers, supported by their partners and start-ups, are investing massively in research, development and technology, exploring several avenues to improve the environmental and energy efficiency of air transport. Here’s what some of them are doing:

Aircraft manufacturers

Airbus
The European aircraft manufacturer has announced the launch of the first low-carbon commercial aircraft by 2035.

According to CEO, Guillaume Faury, this is a “strategic priority for Airbus”.

The development of a low-carbon aircraft does not require “major technological breakthrough” as Airbus already uses hydrogen propulsion for the Ariane rocket and its satellites.

Airbus has unveiled three concepts grouped under the code zeroe (for zero emission) brand.

The first is a conventional looking turbofan aircraft able to carry 120 to 200 passengers on routes of up to 3,500km.

The second is a turboprop aircraft with a capacity of 100 passengers for short-haul routes. These models, featuring modified gas turbines for propulsion, complemented by hybrid electrical motors run by fuel cells, don’t require investment in completely new technologies. However, that can’t be said of the third disruptive concept, the hydrogen-powered blended wing design.

Faury pointed out that the third concept is “more disruptive and allows us to study a completely different configuration for hydrogen storage and propulsion”.

This concept, which is similar to the Maveric demonstrator presented by Airbus at the last Singapore Airshow, allows more solutions.

“Hydrogen is one of the most promising technology breakthroughs because it can be obtained from renewable energy and does not produce emissions,” explained Jean-Brice Dumont, Airbus executive VP engineering.

According to Dumont, hydrogen is the only scalable energy-storage system capable of stabilising electricity networks fed by wind turbines and solar panels.

He added that safety remains an essential component for integrating hydrogen, which has about four times the volume for the same amount of energy of kerosene based jet-fuel.

The main challenge will be to certify the demonstrators to airworthiness standards. Over the next five-six years, much progress will be needed regarding a full-scale prototype.

Boeing
For more than 10 years, Boeing “has positioned itself as a leader in making aircraft fuel sustainable”. This fuel is used every day around the world on more than 250,000 flights. It can reduce emissions by up to 80% throughout the fuel lifecycle, and is fully compatible with aircraft currently in service and those that will fly tomorrow.

According to Jean-Marc Fron, managing director of Boeing France, three-quarters of investments in research and development – more than 50 billion Euros ($60.37bn) since 2003 – have been dedicated to improve in-flight efficiency.

Launched in 2012, the ecoDemonstrator programme has evaluated more than 160 projects on seven aircraft. The American aircraft manufacturer is pursuing extensive research in the field of hydrogen.

It is also working on the transonic truss braced wing (TTBW) concept with NASA. This innovative technology aims to improve energy efficiency.

Boeing believes that electric propulsion holds promise for urban air vehicles, as well as small fixed-wing aircraft that serve regional routes, and will require renewable energy grids to sustainably recharge and fly emission-free.

The aircraft manufacturer has also launched a hybrid propulsion aircraft project with the start-up Zunum Aero and Jet-Blue Ventures Services. The partners are developing hybrid-electric regional aircraft, delivering unmatched door-to-door speeds and reduced costs for flights from 700 miles at launch to more than 1,000 miles by 2030.

Engine manufacturers

Safran
For many years, Safran Group has devoted 75% of its research and technology (R&T) investments to limiting the environmental impact of air transport.

For Safran R&T director, Stéphane Cueille, three pillars are needed to reach the expected targets. These include:
• Developing lighter aircraft equipped with ultra-efficient engines in terms of energy;
• Progress in alternative fuels, including biofuels, synthetic fuels and hydrogen; and
• Optimisation of flight operations.

It will also be necessary to replace kerosene with a “low or zero carbon” fuel.

Safran is aiming to capitalise on the achievements of the ‘open rotor’ demonstrator – a key component of its plan to develop a propulsion system to meet aircraft manufacturers’ future needs towards 2030. It would provide at least 50% of the gain targeted for the aircraft.

“These projects help prepare technologies compatible with the goal of developing ultra-efficient aircraft using ‘green’ fuels instead of kerosene,” said Cueille. “A huge effort is being made to come up with future disruptive engines, but we are also working on hydrogen for the Hyperion 2.1 aircraft – the NASA/Boeing X48B-inspired blended wing body aircraft.

Rolls-Royce
Rolls-Royce aims to play a leading role in pioneering a resilient, inclusive, net zero carbon future.

Alan Newby, the company’s director aerospace technology and future programmes said: “Our civil aerospace sustainability strategy is built around three pillars – improve the gas turbine; promote sustainable aviation fuels (SAFs); and be at the forefront of developing innovative propulsion technologies.”

The UK engine manufacturer is working on a range of technologies to meet the demands of different missions, ranging from major improvements to gas turbines beyond the current Trent family, through more radial electric and hybrid electric solutions, to alternative energy sources, such as sustainable aviation fuels and hydrogen.

“On the-Fan X programme, we have created a hybrid-electric power generation system at a scale never previously seen in our industry,” said Newby. “It comprises an embedded AE2100 gas turbine driving a 2.5MW generator and 3000V power electronics, and an electric propulsion unit.”

UltraFan is another key element of Roll-Royce’s sustainability strategy. According to Newby, it will redefine the world of engines and set new standards in efficiency and sustainability, offering a 25% reduction in emissions.

In addition, Rolls-Royce has announced a ground-test campaign with a Trent 1000 engine powered 100% by SAF. This biofuel is produced by World Energy, supplied by Shell Aviation and delivered by SkyNRG.

According to Newby, this unblended fuel could reduce net engine life-cycle CO2 emissions by more than 75%.

Rolls-Royce has been working on a 100% electric aircraft concept since early 2019. This initiative – accelerating the electrification of flight (ACCEL) – aims to develop technology and supply chain knowledge to generate the development of future flight concepts.

“Rolls-Royce’s ultimate goal is to launch certified systems for all three market segments (small propeller planes, urban air mobility, and commuters) within three to five years,” explained Newby.

Type of energy needed

From a technological point of view, the most accessible solution lies in fuels that can be used directly in existing aircraft mixed with kerosene.

The engine technologies currently in service can already incorporate up to 50% of biofuels (made from sustainable biomass not in competition with food).

The next generation of ultra-efficient engine will incorporate up to 100% of these biomass fuels.

Another option involves synthetic fuels, resulting from a virtuous electrosynthesis process, which extracts carbon from the atmosphere or from industrial fumes, and which thus opens up the prospect of a fuel that is completely emission neutral.

Other issues that must be tackled include:
•The availability of decarbonised hydrogen in sufficient quantity and at an acceptable cost;
• The supply of liquid hydrogen in airports; and
• Fuelling technologies for aircraft.

A global transition to hydrogen means that there’s a need to rethink several components of the aviation ecosystem.