t is no secret that the aeronautics industry is one of the big CO2 emissions emitters as it generates 2% of green-house gases worldwide. In order to fight climate change, the industry needs to reinvent itself and find ways to lower its environmental impact. What solutions could the future of aviation bring? Are we at the beginning of a new era?
Since the beginning of the health crisis due to Covid-19 pandemic, the aviation industry is facing an unprecedented crisis in a harsh ecological situation. According to the IATA predictions, air traffic should return to normal only in 2024. The key players of aviation are forced to engage shareholders in long-term perspectives by building ambitious and disruptive projects. In view of the environmental context, new regulation and consumer expectations, the new long-term vision is clear: the new era of aviation is clean and carbon-free.
Electric planes have already appeared in the 1970s. Indeed, electric aircrafts were for many years just experimental devices with a very little range and almost no payload at all. However, since then, the number of electric plane projects has drastically increased to such an amount, that given the advancement of the innovations in aviation circles, the commercial use of electric aircrafts seems closer than ever. The first steps towards the commercial use of electric aircraft have already been made, which is needed to make emission-free aviation feasible.
First of all, let's have a look on electric planes with batteries. Five years ago, as its battery-powered electric propulsion has the smallest impact on the environment, there was a boom of electrically propelled aircraft projects. It actually is the cleanest way to operate an aircraft, with the two main advantages: zero flight emissions, as it produces no combustion gases at all, and almost no noise pollution. It is considerably quieter than other aeroplanes. Of course, we cannot say it is entirely clean, as the manufacturing and recycling of batteries must be put into consideration. However, the electrically propelled aircraft present a strategic advantage to combat carbon emissions and noise pollution, which has also grown to an important environmental issue in airports and its surroundings. Another prominent advantage of electric propulsion is that its technology has already existed since decades and is improving very quickly.
At the beginning, electric aircrafts were too heavy, because of the important battery weight. This caused the lack of manoeuvrability and functionality, as the maximum weight was already reached with only one pilot onboard. Also, the airborne capacity of the first battery-powered electric planes was only a few minutes. Indeed, the weight, short autonomy and the charging time are the principal disadvantages of the battery technology. Luckily, thanks to innovations inspired by the automotive industry, battery manufacturers have significantly improved their technology, so the power of batteries has risen importantly, which nowadays allows up to an hour-long flight.Since 2019, the number of electric flights have flourished, allowed by the innovation and technical progress. The shift in aviation circles started in June 2019 with a flight of BRM Aero equipped with an Electric Propulsion System and a Cessna 337 with a hybrid engine.
The Canadian commuter airline Harbour Air, which promised to fly an all-electric commercial aircraft before the end of 2019, developed together with MagniX, a Washington-based company developing electric propulsion systems for aircraft, the first “ePlane”. They spent several months replacing the six-passenger Beaver’s Pratt & Whitney P-985 Wasp Junior piston engine with a MagniX-made magni500 electric propulsion system. The history was made on 10 December 2019, when a Harbour Air DHC-2 Beaver (first commercial passenger ePlane) completed its first flight equipped with an all-electric propulsion system. However, given the constraints of all-electric aircraft, the flight lasted only about 4 minutes. As the plane relies on energy from batteries, it has only a fraction of the energy density found in liquid fuels. Such constraint means that an all-electric aircraft can hardly match the range or flight duration of aircraft powered by fuel-burning engines. But electric propulsion systems burn no fuel and have fewer moving parts and less complexity than fuel-burning engines. That means they cost significantly less to operate - about half as much as internal combustion engines. That's why MagniX joined AeroTEC, a leading independent company focused on aerospace testing, engineering and certification, in order to bring all-electric flight to consumer air travel. The fruit of their project - a tranformation of the iconic Cessna Caravan that has been a workhorse of industry moving people and transporting goods on short routes for decades, to an eCaravan. An electric-powered Cessna 208B Grand Caravan was the largest all-electric passenger or cargo aircraft to date. It took off a Moses Lake runway for a maiden flight on 28 May 2020, marking another milestone in all-electric propulsion system's aviation history. The “eCaravan” flew for about half an hour at more than 100 mph to an altitude of around 2,500 feet and made a few turns before landing. Weighing in at over 4 tons, with a wingspan of over 50 feet and room for nine passengers, it's the largest electric plane ever to have flown, making . During the Grand Caravan’s 28min test flight, the Magni500, a 750-horsepower (560 kW) electric motor, supplied with energy of a 750V lithium-ion battery system weighing roughly one tonne, consumed only about 6 USD worth of electricity, instead of 300 USD of kerosene. In addition to zero flight emissions and lower fuel costs, the use of electric motors is also expected to significantly reduce maintenance costs, eliminating the need for extensive engine overhauls every 3-4,000 hours of operation. In fact, electric motors are lighter than fossil fuel engines, don't need as much maintenance and last much longer before they need to be replaced.
According to MagniX's chief executive Roei Ganzarski, electric aircraft can be better than fossil-fuel propeller planes over distances of up to 1,000 miles, which represents more than half of all passenger flights worldwide, knowing that the airlines have been using jets or turboprops for those flights until now. Turbo-propelled Caravan planes are since decades used around the world to carry passengers and haul cargo, therefore MagniX and AeroTEC hope that their eCaravan may take on some of those short-haul regional airline routes, helping to pave the way for an industry-wide decarbonisation movement, as there is no doubt that electric airplanes are quieter, safer and cheaper to run than fossil fuel planes. As said Ganzarski: "As long as the electricity is generated cleanly, electric aircraft create no atmospheric carbon emissions."
Therefore, the first flight of the eCaravan is clearly another step on the road to operating these short-haul aircraft at a fraction of the cost and with zero emissions. MagniX and AeroTEC are working on certifying their electric aircraft by the Federal Aviation Administration. The eCaravan has to go through several months of further testing, both aloft and on the ground, and is expected to get certified by the end of 2021. By then, Ganzarski predicts battery technology will have advanced to where the Grand Caravan will be able to operate 160km flights carrying a full load of nine passengers. Materials scientist Shirley Meng of the University of California, San Diego is part of the Battery 500 Consortium working on new battery designs. She explained that nowadays, the commercial lithium-ion batteries can store about 250 watt-hours of electricity per kilogram, but new designs could double that in a few years. Indeed, this depends on how quickly factories can be equipped to make them.And let's not forget that electric propelled planed can also take advantage of battery technologies pioneered by electric cars, such as Tesla or its competitor GM, who are about to reveal "million-mile" batteries based on chemistries that can increase their lifetimes and drive down their prices. Ganzarski believes that even hough aircraft battery packs are different, they use the same basic designs, which will allow that the new battery technologies from electric cars will make their way to electric aviation circles.
In June 2020, the European Union Aviation Safety Agency announced the certification of a battery-powered electric airplane - the Pipistrel's Velis Electro. It became the very first fully electric aircraft certified in the world. The certification team included experts from the Swiss and French authorities, in order to prepare and facilitate the entry into service of the Velis Electro in the two countries. Pipistrel revealed it already received 31 orders for the plane from seven countries. MonAsia considers the obtention of EASA type certification for the Velis Electro as an important milestone in the quest for environmentally sustainable aviation.
In this light, electric commercial flights appear imminent. Moreover, UK budget carrier EasyJet also decided to initiate the development of their short-haul commercial-electric flights in partnership with Wright Electric - an American startup company that should develop the 186-seat electric aircraft, known as Wright 1. Wright Electric is planning to start ground tests of a motor intended to provide propulsion for an electric airliner this year, and to conduct flight tests in 2022. We are convinced that soon the electric commercial planes will enable the offering of flying services of people and packages in a way previously not possible.
Thanks to the striving innovation and enormous progress, the electric propulsion and battery-power gained on the credibility. The electricity is now recognised as a feasible alternative to small aircrafts and short commercial flights, however, long-haul electric aircrafts do not seem realistic yet. The power necessary to fly planes like Boeing 787 or Airbus A350 would need an enormous weight in terms of battery, that is not reachable so far. One of such projects that has been halted is the Airbus/Rolls-Royce/Siemens E-Fan X, cancelled by a Airbus and Rolls-Royce joint decision in April 2020 during the COVID-19 health crisis. Announced in November 2017, it followed previous electric flight demonstrators towards sustainable transport for the European Commission’s Flightpath 2050 Vision. The E-Fan X is a BAe 146 with its starboard inboard turbofan replaced by a Siemens 2 MW (2,700 hp) electric motor, adapted by Rolls-Royce and powered by its AE2100 turboshaft, controlled and integrated by Airbus with a 2t battery. While significant advances in battery technology have been made in the last 10 years, batteries are still so heavy that electric planes can't be expected to fully replace fossil fuel aircraft in the foreseeable future. This showed that nowadays, battery-powered electric planes are only a reality for small aircrafts, not yet for long-haul flights. For example, the eCaravan we presented above has a range of about 100 miles, but a turbo-propelled Cessna Caravan with the same weight of kerosene can fly about 1,500 miles.
However, we believe that in the next decades, the innovations will bring the concept to new scale and break down today's barriers. We trust that the quest for electric aircrafts can actually drive the development of better batteries and fuel cells for airliners, as well as for the other technological sectors. MagniX for example is currently studying other technologies, including lithium-sulfur batteries and hydrogen fuel cells. This being said, let's shed some light on hydrogen and fuel cells as another technology that could allow long-haul electric propulsion without the limitations of batteries.
For decades, NASA has relied upon hydrogen gas as rocket fuel to deliver crew and cargo to space. and thanks to their space shuttle vehicles, the agency has gained significant experience in the handling of hydrogen. NASA has used hydrogen in aerospace since the 1960's in two ways: as fuel cells and as combustion. Today it represents a giant leap in electric propulsion as a way towards zero-emission flight.
But we should keep in mind that hydrogen fuel cells offer alternative to batteries and not to electric motors. Indeed, hydrogen replaces the need for batteries, because it is directly transformed into electricity through fuel cells. This electricity is then used in the electric motor. Hydrogen fuel cells generate zero emissions, with water as the only byproduct, which is a great asset for clean aviation on its decarbonisation journey.
By removing batteries from the equation thanks to the direct production of electricity from hydrogen, the main advantage of fuel cells is that it gets rid of the weight problem posed by heavy batteries. Instead, only a light alternative for temporary storage is necessary, as the fuel cells are relatively light and offer a great power-to-weight ratio. But they require a lot of space and the storage and use of hydrogen poses unique challenges, especially at high levels of altitude. Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks (350–700 bar [5,000–10,000 psi] tank pressure). Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C. Due to its ease of leaking as a gaseous fuel, low-energy ignition, wide range of combustible fuel-air mixtures, buoyancy, and its ability to embrittle metals must be accounted for to ensure safe operation and the manufacturers are still learning how to manage this technology.
On September 24th 2020, Zero&Avia, the leading innovator in decarbonising commercial aviation, focused on hydrogen-electric aviation solutions, completed the world's first hydrogen fuel cell powered flight of a commercial-grade aircraft. The retrofitted Piper M-class six-seat plane completed taxi, takeoff, a full pattern circuit, and landing at the company’s R&D facility in Cranfield, England. This major milestone on the road to commercial zero-emission flight is part of the "HyFlyer project", a sequential R&D programme supported by the UK Government. It aims to decarbonise medium range small passenger aircraft by demonstrating powertrain technology to replace conventional piston engines in propeller aircraft. MonAsia sees this achievement as the first step to realising the transformational possibilities of moving from fossil fuels to zero-emission hydrogen as the primary energy source for commercial aviation. Moreover, hydrogen-powered aircraft might match the flight distances and payload of the current fossil fuel aircraft.
As we already mentioned, the power-to-weight ratio of hydrogen fuel cells allows aircrafts equipped with this propulsion system to be eligible for long-haul travel. Moreover, hydrogen also has the advantage of being easily accepted within aeronautics industry. The infrastructures that already exist have the capacity to refuel and could easily be adapted for hydrogen, while in the case of battery-powered electric propulsion, batteries would require a drastic transformation of the industry’s value chain. It is for that reason that Airbus decided to work on a zero emission hydrogen-powered aircraft for 2035. Lately, the company presented hybrid concepts using hydrogen fuel cells with hydrogen combustion in modified gas turbine engines.
Indeed, the fact that there is no experience of mass market so far, together with the difficulty to get green hydrogen and store it are the main disadvantages, but zero-emission hydrogen-electric propulsion solution for aviation, initially targeting existing airframes flying up to 500 miles and hopefully more has many pertinent arguments in its favour for the future long-haul flights.
Another important thing to keep in mind is the political aspect of this transition. As we know, the European Commission is pushing the development of green hydrogen, especially to compensate for its increasing gap in battery manufacturing. By doing this, EU countries position themselves strategically among future energy markets. Fortunately, the aeronautics industry can count on strong support for this sector to develop, with government aid (France, Norway, UK, Germany) and large-scale investment from global players such as Air Liquide and Engie.
This being said, hydrogen is positioned both as a complement and an alternative to batteries. Aviation will need these technologies to coexist in order to significantly reduce the industry’s environmental impact. The level of maturity of many pro-environmental technological innovations we mentioned above, as well as the strong political will allows the aviation industry to count on industry pioneers to continue breaking down barriers through electric propulsion and fuel cells. Through innovation, political synergy and economic intent, a sustainable technological revolution could gain momentum in the aeronautics industry.