Aviation must be sustainable: In ten years, domestic aircraft may have charging cables
It is the year 2032, and despite the fact that DSB has now for several years operated the new high-speed electric trains and timetables between the Danish cities, the trip we are taking from Aalborg to Copenhagen today is by plane—not a noisy turboprop plane as ten years ago, but a modern electric plane.
The airline Electric Air Denmark has been operating the route with the ES-19 aircraft from the Swedish manufacturer Heart Aerospace for two years. As the number indicates, there is room for 19 passengers, and all the seats are occupied on the four daily flights. Just before departure, the charging cable is disconnected from the battery and we steadily taxi to the runway accompanied by the sound of a loud buzz of the four propellers.
This is how an ordinary day in a domestic Danish airport could look like in the next decade.
Prime Minister Mette Frederiksen used a part of her 2022 New Year’s address to talk about green air traffic. She said, among other things: We have to make flying green. Therefore, the government will set an ambitious goal: Danes must have the possibility of flying green on a domestic route by 2025 at the latest. And by 2030 at the latest, we must be able to fly completely green within Denmark.Domestic flights in the New Year’s address
Eviation Alice
Number of passengers: 9
Max. rate of climb: 2,000 ft/min
Range: 815 km
Max. takeoff weight (MTOW): 7,500 kg
Powerplant: 2 x 640 kW
On the market: 2024
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Today, global aviation is responsible for 2–3 percent of man-made CO2 emissions, and routes shorter than 400 km account for 9 percent of emissions from aviation. But when it comes to air traffic and the number of new routes and passengers, all arrows point in the same direction—upwards.
Despite COVID-19, air traffic will already be back at the same level as before the pandemic in 2024 (approximately 8 billion passengers annually), and the International Air Transport Association (IATA) expects the number of passengers to increase by between 1.5 and 3.8 percent per year as we approach 2024. That can mean up to 19 billion passengers per year in 2040.
The prospect of a huge increase in both passengers and cargo in the airspace has, among other things, motivated the EU to launch the European Partnership on Clean Aviation in November this year with the aim of ensuring CO2-neutral aviation by 2050. The USA has also launched programs to reduce CO2 and NOx emissions as well as to reduce noise from aviation—all on the basis of the projection that air traffic will increase, which will require new solutions.
Heavy batteries
One of the solutions is electric aircraft with batteries used for energy storage. Most experts agree that this solution is particularly suitable for short-haul routes of up to 500 km. The challenge is first and foremost the specific energy of the batteries. Jet fuel has a specific energy of approximately 12,000 Wh/kg, while the best batteries today have a specific energy of approximately 250 Wh/kg, i.e. they are almost 50 times smaller. On top of that, jet fuel is consumed and thus makes traditional aircraft lighter during flight. The battery weighs the same at take-off and landing. Number of passengers: 19
Heart Aerospace ES-19
Range: 401 km
Max. takeoff weight (MTOW): 8,581 kg
Powerplant: 4 x 400 kW
On the market: 2026
On the other hand, an electric engine is far more efficient and weighs less than a turboprop engine, so we have to reckon with the fact that “fuel” and powerplant in an electric aircraft today weigh roughly at least 20 times more than in a propeller aircraft.
There are, of course, developments underway that will make the batteries better, but it is not likely that they will reach jet fuel in specific energy in the foreseeable future. On the other hand, there are many short-haul routes around the world on which electric aircraft could be used, and everything points to their number becoming even greater.
Electric aircraft are in a very early stage right now, but the prospect of stricter requirements for sustainable aviation from both customers and authorities could set in motion a revolution like the one we are currently seeing in the transition from cars with internal combustion engines to pure electric cars.
Ambitious Norwegian goals
Norway is already familiar with this process. Today, the country is famous for the largest proportion of electric cars in the world, and there is already a plan to go down the same path when it comes to electric aircraft on most of the country’s domestic routes. This is confirmed by Olav Mosvold Larsen, head of the carbon reduction programme at Avinor, the state-owned company tasked with operating Norway’s 43 airports.
The possibilities for electric aircraft on many of the country’s domestic routes started being investigated as early as 2015. This led to a proposal by Avinor and the Civil Aviation Authority of Norway that the first regular domestic scheduled flight running on electricity should be ready in 2030, and that all domestic civil aviation in Norway should be electrified by 2040.
“People said we were completely crazy at the time. But today, I am very optimistic. There are challenges, of course, but as we can see now, there are no insurmountable technological obstacles for us to achieve the goal,” Olav Mosvold Larsen says and at same time admits that it is by no means a small task.
Number of passengers: 2 (incl. 1 pilot)
Pipistrel Velis Electro
Max. rate of climb: 650 ft/min
Endurance: 50 min
Max. takeoff weight (MTOW): 600 kg
Powerplant: 57.6 kW
On the market: now
The development and the procurement of aircraft is one thing, but the airports must also be prepared to be able to handle electric aircraft. Many of the routes in Norway are characterized by relatively short distance and the fact that the aircraft has to fly over a mountain or a fjord. Airports are also often small and have short runways.
“So we have very different challenges in various airports. In some places there may be only a few departures a day; the challenge that charging represents may not be so great there. But in the larger airports, we have to build a charging network in which several smaller aircraft with batteries of up to 950 kWh can charge at the same time,” Olav Mosvold Larsen explains.
Avinor has entered into a close collaboration with Widerøe, which is the largest airline on the short-haul routes, and has together with SAS and a few other partners purchased a Velis Electro 600 electric aircraft from Pipistrel. The same aircraft has also recently been put into service in the Danish Defence as a trainer aircraft.
The aircraft is only meant for short trips, approximately 45 minutes maximum, and can only transport two people. So a completely different scale is needed for it to make sense for ordinary passengers to take an electric aircraft.
Fortunately, that development is well underway, and last autumn, one of the world’s largest airlines, United Airlines, announced that it had ordered 100 aircraft from the Swedish company Heart Aerospace. The aircraft, which has been named ES-19, will have room for 19 passengers and a range of 400 km with today’s battery technology.
Heart Aerospace also emphasized that once the aircraft is ready and certified as expected in 2026, the first routes will be short-haul flights, for example between islands or over mountain ranges, from valley to valley. But there will also be a market for electric aircraft in a country like Indonesia, which consists of 17,000 islands and where domestic flights have quadrupled within the last ten years.
New aircraft manufacturers take the lead
Just as we have seen in the electric car market, a large number of new aircraft manufacturers similar to Heart Aerospace has emerged. This applies, for example, to the Israeli company Aviation, which plans to build an aircraft for nine passengers with a range of 815 km. The aircraft will be built in the USA, and Aviation hopes that it will be ready for commercial flights in 2024. So far, the transport company DHL has ordered 12 aircraft in the cargo version.
Number of passengers: 5 (incl. 1 pilot)
Beta Technologies ALIA-250
Range: 463 km (250 nautical miles)
Max. speed: 270 km/h
Endurance: 50 min
Max. takeoff weight (MTOW): 3,174 kg
** On the market: ** provisionally approved by the U.S. Air Force for test flights
On a somewhat larger scale, American start-up company Wright Electric has announced that it will build an electric aircraft for 100 passengers. Wright Electric is collaborating with NASA and the U.S. Department of Energy, and the first tests of a new engine are scheduled to begin in 2023.
In 2026, the technology will be built on the basis of a known aircraft design, BAe 146, which can fly for an hour on pure electrical energy. Rather than a large battery, it is very likely that Wright Electric will use a fuel cell powered by hydrogen to produce the electrical energy.
Some might get the idea that the major aircraft manufacturers have been asleep at the wheel. However, this is not true, because in recent years several high-profile projects and investments came from both Airbus and Boeing. For example, Boeing, together with JetBlue Airways, has invested in Zunum Aero, a start-up company which aimed to build a test aircraft with a capacity of 12 passengers and later a hybrid electric aircraft with a capacity of 50 passengers.
But in 2018, Zunum Aero went bankrupt, and Boeing has since focused more on developing sustainable fuels for traditional jet engines.
Airbus presented a small pure electric aircraft under the name E-Fan with technology from Siemens, among others, already in 2014. In 2017, the larger E-Fan X demonstrator in collaboration with Rolls-Royce was revealed. It made it possible to test large electric engines and the battery system. But in 2020, the parties somewhat surprisingly decided to end the project, and Airbus is today focusing primarily on sustainable hydrogen as aviation fuel.
While the number of development projects for “real” aircraft with batteries is still limited, it is a completely different story when it comes to electric passenger drones, also called eVTOL (electric vertical take-off and landing) aircraft. Hundreds of projects are underway worldwide with investments worth billions of dollars. Many large tech companies and automobile and aircraft manufacturers are involved, including Uber, Aston Martin and Airbus. For drones, the range is generally short, usually less than 160 km, and the maximum number of people on board rarely exceeds four. The routes are often meant to be between major city centres (New Jersey–New York) or between airports and the city centre (Heathrow–London). It is expected that many of the drones will fly autonomously. German company Volocopter, one of the pioneers in this technology, has developed an autonomous personal drone called VoloCity with room for two people. The range is 35 km and the max. airspeed is 110 km/h. VoloCity has been approved for test flights in Germany, Dubai, Helsinki, and Singapore.
What about drones?
Three concept aircraft, called ZEROe, are in the planning stage, and Airbus expects to be able to offer the first to customers in 2035. These are not small aircraft with limited range. Airbus expects the range to be over 3,500 km for an aircraft with room for just under 200 passengers. They will all be powered by a modified gas turbine, with hydrogen as the fuel.
The big aircraft manufacturers are thus not completely out of the electric race, and they definitely want to limit the risk that a newcomer will be able to “pull a Tesla” and quickly take over a very large part of a lucrative market.
Few seats are not cost-efficient
In Denmark, it may be appropriate to consult DAT, which currently serves six Danish routes, among which the route between Copenhagen and Aalborg has the most departures. Jesper Rungholm is the CEO and also a captain, and he regularly sits in the cockpit himself, flying Danes out on holiday and around the country.
Recently, DAT retired the legendary McDonnell Douglas MD-83 aircraft. MD-83 was nicknamed “Mad Dog”—possibly because of the initials MD, but certainly also because of the noise, and because the take-off almost felt like being launched in a rocket.
Today, DAT flies on domestic routes primarily with the smaller twin-engine turboprop aircraft from the French-Italian aircraft manufacturer ATR, and Jesper Rungholm reckons that aircraft of this type will also dominate for many years, because his biggest problem with electric aircraft is not range, but the number of seats.
“There is no doubt that we need to find alternatives to the aircraft we have today, but first and foremost we need to look at the business model. I don’t see the cost efficiency in an aircraft with just 19 seats. Airport charges for such an aircraft would be almost the same as for a 90-seat one,” he says.
Jesper Rungholm also questions the expansion of the infrastructure in the small airports, where the electricity grid must be able to handle the load of charging the aircraft. That is why he is part of a design group at one of the major aircraft manufacturers. The goal is to build an aircraft for short-haul routes that is designed to use green fuels based on hydrogen produced via electrolysis—so-called e-fuels.
“Of course, I don’t want to dismiss pure electric aircraft, but we need up to 40–50 seats and a range of 250 nautical miles (463 km), and it must be possible to charge them in 20 minutes before I believe that they are a realistic option,” he says.
Smaller aircraft on shorter routes
But there may also be other possibilities for electric aviation than the known routes between the major Danish cities. With smaller aircraft not making as much noise, there will be a greater supply of small airports. What if we do not have to fly back and forth from Copenhagen, but instead can take an electric aircraft from e.g. Roskilde directly to the local airport in Thisted and on to Esbjerg the next day?
Smaller electric aircraft could thus become a truly sustainable alternative to cars and trains to save time. Martin Porsgaard, director of NISA (Nordic Initiative for Sustainable Aviation), believes so. In fact, he does not rule out that in ten years we may see more new airlines emerge:
“We know, for example, that a third of all domestic flights in Sweden have less than 20 passengers. So if the current players in aviation do not see the opportunities, I think new ones may emerge that will take over a part of the market,” he says and also mentions the route from Sønderborg to Copenhagen as an obvious place to deploy electric aircraft.
Once it becomes feasible, Martin Porsgaard believes that there will be pressure from both the public and companies:
“I think Denmark is a little behind in the understanding of the aviation of the future right now. But once the aircraft hit the market in the mid-2020s, I think that will change, and we will be ready to fly electric.”
After about 45 minutes in the air, I am now ready to land in Copenhagen. The descent itself is almost completely silent, and the landing gear hits the runway with the characteristic bump.
We taxi to the terminal, and at the same time as the door opens, the ground crew shows up with a charging cable.
