AviationIssue 03 - 2022MAGAZINE
GBO_ Electrification of aerospace

Flying high: Electrification of aerospace

The aircraft industry's continued expansion has boosted production rates and allowed Airbus and Boeing to seize the top positions in the industry

A small British start-up is trying to write a little history of its own by becoming one of the forerunners of commercial electrified aviation from a tiny office overlooking an airfield that was once the base of the United Kingdom’s first Spitfire squadron.

In order to compete in the regional aviation market, Faradair intends to build and commercialize a hybrid-electric passenger aircraft. It might have up to 19 seats and be propelled by an electric motor-driven fan. A little gas turbine would supply the required electricity.

It would also include a triple-level wing to add additional lift and enable takeoffs and landings from short runways. Even though it had cutting-edge aerodynamics, this would give it a little resemblance to a fighter from World War I.

Faradair CEO Neil Cloughley says that such a plane would have fewer moving parts than a typical propeller aircraft, making it less expensive to operate. It would also emit less emission and be considerably quieter.

“Why do we not use aeroplanes like we would a bus?” Neil Cloughley asks during an interaction with BBC.

“The reason is the cost of operation, primarily. Also if you start using lots of aeroplanes it creates a lot of noise, and of course, we have now got into an age where sustainability really is a key part of our future. So we decided we would come up with an aircraft that would not only be economic to use, and therefore cost-effective, but would also be quiet and sustainable,” Neil Cloughley added.

According to him, the Faradair design would enable quick travels between places like London and Manchester for £25 each way, which is much less expensive than a rail ticket.

To eradicate the need for substantial investments in road or rail systems, such planes could provide a transport lifeline from small airstrips in more isolated or inaccessible places. The aircraft will be in the air by 2025, and commercial use will begin in 2027.

At a time when governments all over the globe are looking for ways to cut carbon emissions, Faradair is far from the only company to recognize the promise of electric aviation and at the same time, its project is also not the most challenging.

Wright Electric, a startup situated in California, for instance, wants to put into service a 100-seat aircraft that is entirely electric by the middle of the decade. Based on the current Bae146, it would include four electric motors in place of the turbofan engines.

According to the firm, which has a partnership with Easyjet, the aircraft would be used for one-hour flights, enabling it to serve routes like London-Paris, New York-Washington, or Hong Kong-Taipei.

The aircraft will, however, operate as a hybrid during testing. One of the four engines will be switched out at first, with the remaining three following suit, if the tests are successful.

According to Wright Electric CEO Jeffrey Engler, prospective clients believe this is a solid strategy and one they may use when the aircraft goes into production.

“When we spoke to the airlines, they said, ‘Well, why don’t you go hybrid initially, instead of full-electric from the start?'” Jeffrey Engler explains.

He said, “Just like the car industry started with hybrids as well. So that’s something we’re looking into.”
Even the best batteries carry significantly less energy per kilogram than conventional aviation fuels, making them much too heavy to operate an airliner over long distances. This is the major reason why electrifying aircraft is so challenging.

Dr. Andreas Strohmayer, head of the University of Stuttgart’s Institute of Aircraft Design, said, “The specific energy of today’s batteries is far from what you would need.”

The Institute initially flew its own experimental two-seater electric plane, the e-Genius, more than 10 years ago. Since the mid-1990s, the Institute has been studying the potential of electric and hybrid aviation.

“We build our own battery systems for our electric aircraft. We are getting in the region of 200 watt [hours] per kilogram, where we would need 1,000 or 1,500. So we are far from what we would need for a large aircraft,” Dr. Andreas Strohmayer explains.

His opinion is that modern technology can be used to create small, light electric aircraft with up to six seats.
Even though it would be “near the edge of what is now conceivable,” Dr. Andreas Strohmayer thinks it should be possible to construct a commuter plane with up to 19 seats that run solely on batteries.

This would include the nine-seater Alice aeroplane being built by the Israeli company Eviation. The aeroplane, which has been in development for many years, is intended to go up to 600 miles entirely on electric power.

In contrast, anything big would require a hybrid design, combining electric motors with internal combustion engines or on-board generators.

According to Dr. Andreas Strohmayer, these types of aircraft have the ability to build new aviation networks by transporting passengers over short distances from local airfields to regional hubs. They would be able to go up to 500 kilometres there on larger hybrid planes.

“It would be a denser aviation network. It would be of most use in regions like Scandinavia or in mountainous areas, where you can’t really just build networks of high-speed railways. There are places like Indonesia, Polynesia, where you have all these islands that have to be connected. There are places in the world where such networks are desperately needed,” Dr. Andreas Strohmayer added. This summer, Eviation will conduct the first Alice test flights.

However, such technology is not expected to be of much value on long-haul flights, which may help to explain why Airbus, a major player in the European aerospace industry, has determined that its own priorities lie elsewhere.

In collaboration with Rolls-Royce and Siemens, the firm started building the E-Fan X, a prototype hybrid aircraft, in 2017. It was based on the existing Bae146, just like Wright Electric’s proposal.

But the programme was cancelled three years later. The section of Airbus Upnext, which is in charge of investigating new technologies, is led by Dr. Sandra Bour-Schaeffer, and she believes it was the right choice.

Dr. Sandra Bour-Schaeffer said, “Our focus is to achieve carbon neutrality by 2050. In order to achieve that we need to look at two different technologies, associated with different time horizons.”

The firm is concentrating on employing sustainable aviation fuels generated from waste and renewable sources in the short term to cut emissions.

Beyond that, Airbus is focused on developing a new generation of environmentally friendly aircraft that are powered by hydrogen.

“Our ambition is to bring the first zero-emission commercial aircraft based on hydrogen to the market in 2035. I already have teams working on cryogenic and superconducting technologies. We are already exploring what will come next,” Dr. Sandra Bour-Schaeffer added.

Maintenance and Servicing Organizations should reevaluate their operations to address issues like what kind of physical infrastructure will be required moving forward. This is because aircraft electrification could present a huge opportunity. The number of extra batteries that will need to be kept ready at airports, the best place for charging stations, and even how long it will take to charge or replace the batteries in between flights are all issues that need to be taken into account. The latter will be a major factor for airlines to take into account, as an electric aircraft won’t be making any money while it is being recharged.

The aircraft industry’s continued expansion has boosted production rates and allowed Airbus and Boeing to seize the top positions in the industry. The mergers and acquisitions of smaller businesses have only served to strengthen this duopoly (Bombardier and Embraer). Because this new paradigm in propulsion levels the playing field for new players entering the market, the change to electrification poses a risk to incumbents.

The current energy storage capacity per unit weight of batteries, as well as the development of lightweight and efficient electrical generators, motors, and power electronics capable of converting, conditioning, and switching to high voltage power, are just a few of the major technical challenges that both existing players and new entrants will have to overcome.

The current state-of-the-art battery technology does not deliver enough energy density to be suitable for commercial flights. If a civilian aircraft comes up with this technology in the current scenario, it would require close to 40 times as much battery weight as it could ever take off with, which means that the airframe needs to be on the heavier side. As per an ‘AZO Cleantech’ report, only 8% of aircraft could feasibly be powered by the most energy-dense batteries available right now.

While the growing popularity of electric vehicles is helping the battery technology in this domain to upgrade at a faster pace, energy density is improving as well at a similar rate. Research concepts such as Bye Aerospace’s eFlyer craft and Pipistrel’s Velis Electro have been proven to fly with battery energy densities of around 260 Wh/kg. However, the current generation of electric motors is way heavy for aerospace projects and at the same point in time, less powerful than the existing jet engines.

Also, aircraft manufacturers will need to alter aircraft designs to efficiently integrate an electric propulsion system, which means investment requirements in new manufacturing processes, upgraded facilities, and R&D-related efforts.

As commercial aeroplanes have not departed from the gas turbine-driven architecture for more than 50 years, airworthiness authorities will need to devise methods to certify novel aircraft architectures. In order to move toward greener solutions, the European aviation industry has come together under the leadership of the Advisory Council for Aeronautics Research, which has set ambitious goals like reducing CO2 emissions by 75% per passenger.
As airlines have pledged to an initiative called ‘Fly Net Zero’, under which they will achieve net zero carbon emission by 2050, it brings electric power as a viable alternative in the sector. However, to realize this, the players need to identify a feasible combination of available technologies.

While small-scale aircraft (like the one in Faradair) can serve as an ideal platform for hybrid-electric propulsion systems, the same solution may not be beneficial for medium and long-haul flights, due to the limitations of the current battery technology. These medium and long-haul flight categories are primary revenue sources for the airlines. While the aviation sector has taken up its own climate goals, it has to be a profit-friendly one.

Researchers from UiT The Arctic University of Norway have put forward an electrificationroute as a short-term basis in a paper titled ‘Transportation Engineering’. The study bats for turboelectric designs and says that this solution is the best candidate for a viable electric aircraft. Turboelectric systems store energy in fuel and convert it to electric power to drive propellers. While investing in turboelectric aircraft can be a way forward for the future all-electric aircraft, as it has the potential to solve the less technologically challenging aspects of the electric motor development and aircraft integration, giving the battery technology its own sweet time to get developed. This will set the ball rolling for the phased implementation of the ‘Fly Net Zero’ programme.

While all-electric aircraft configuration is simpler than turboelectric propulsion, the power source for an all-electric jet will be batteries charged from renewable energy sources. It will be a silent aircraft, and the operators won’t need to spend on the fuel front. However, the problem is that the technology we are talking about is currently unfit for medium and long-haul jets, due to the limitations in the current state-of-the-art battery technology.

Beta Technologies’ Alia-250 and Eviation’s Alice and the Lilium Jet have demonstrated that electric-powered flight is possible at small scales, so the airlines can invest in this option and make sure that short-haul air travels witness this innovation first.

Airbus and Renault Group have recently signed a research and development agreement, which aims at enhancing transversalities and synergies to accelerate both companies’ electrification roadmaps, improving their respective range of products. This tie-up will also help Airbus to mature technologies associated with future hybrid-electric aircraft.

As per Airbus’ press release, engineering teams from Renault and the aviation giant will join forces to mature technologies related to energy storage, which remains one of the main roadblocks to the development of long-range electric vehicles. This will cover technological roadblocks related to energy management optimization and battery weight improvement, apart from looking for the best pathways to move from current cell chemistries (advanced lithium-ion) to all solid-state designs which could double the energy density of batteries in the 2030 timeframe.
The joint work will also study the full lifecycle of future batteries, from production to recyclability, in order to prepare for the industrialization of these future battery designs while assessing their carbon footprint across their entire lifecycle.

“For the first time, two European leaders from different industries are sharing engineering knowledge to shape the future of hybrid-electric aircraft. Aviation is an extremely demanding field in terms of both safety and energy consumption, and so is the car industry. At Renault Group, our 10 years of experience in the electric vehicle value chain gives us some of the strongest feedback from the field and expertise in the performance of battery management systems. Driven by the same ambition to innovate and reduce the carbon footprint, our engineering teams are exchanging with those of Airbus to converge transversal technologies that will enable both hybrid aircraft to be operated and the vehicles of tomorrow to be developed,” said Gilles Le Borgne, EVP, Engineering, Renault Group, as quoted by the Aibus’ press note.

Meanwhile, United Airlines has also announced a new investment in battery manufacturer Natron Energy, to boost the electrification of the airline’s ground equipment. As part of its commitment to reduce aircraft emissions, United Airlines has been eyeing its ground operations, where greenhouse gas emissions can be reduced.

Natron Energy produces high-performance sodium-ion batteries, which, compared with lithium-ion batteries, are safer and have greater power density and recharging speed, according to the company. Lithium-ion batteries are common in consumer electronics, but have a tendency to overheat. Natron’s sodium-ion batteries are non-flammable.

The investment is part of United Airlines Ventures, a fund that focuses on investing in sustainable solutions to help the company meet its goal of net-zero emissions by 2050. It was launched in 2021.

Unless and until the difficulties surrounding the existing battery technologies are getting addressed, we may witness that rather than all-electric alternative, medium and long-hauled commercial jets adopt a “More Electric-Hybrid” approach in the near future. However, this could still result in significant advantages through lower emissions and enable the advancement of motors and power electronics for the eventual changeover to purely electric operation.

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