Siemens’ collaboration with Airbus is a milestone on the path to the electrification of aviation. Why did the two companies get together?
Flying into a Hybrid-Electric Future
Siemens and Airbus are convinced that aviation systems will change fundamentally over the next few years. And they intend to play a major role shaping the future of the industry. In April 2016 they agreed to a game-changing collaborative effort. By 2020 they want to prove the viability of hybrid-electric propulsion systems. Martin Nüsseler, project manager from Airbus, and his counterpart at Siemens, Joachim Zoll, discuss their goals and how they plan to work together.
Joachim Zoll: “Airbus is the largest European aircraft manufacturer; it has decades of experience in the development and manufacture of aircraft. We view Airbus as the ideal partner to work with in an effort to profitably establish hybrid-electric propulsion systems in aviation.”
Martin Nüsseler: “Siemens has been working intensively on electrically propelled aircraft engines for years. For applications outside of aeronautics, the company has over a century of extensive drive expertise. This complements our own know-how. The collaboration is a win-win situation for both parties.”
Why are both companies convinced that the future of aviation will be shaped by electric solutions?
Nüsseler: “Flights powered by electric and hybrid-electric engines as well as zero-emissions aviation are the biggest industrial challenges of our time.”
Zoll: “This is also due to the guidelines of the European Commission, which stipulate that aviation needs to achieve a 75 percent reduction in CO2 emissions by 2050 compared to 2000 – even though trends suggest that air traffic is expected to double over that same period of time.”
Nüsseler: “These requirements cannot be met by using conventional technologies. This also applies to plans to reduce noise pollution by 60 percent and the emission of nitrogen oxide by 90 percent. In addition, we anticipate that a hybrid-electric airplane will use around 25 to 50 percent less fuel conventional aircraft. That would drastically reduce operating costs.”
Couldn’t these goals be achieved by optimizing gas and kerosene-based propulsion technologies?
Nüsseler: “No, that approach would not even come close. It is true that improvements will continue to be made in jet engine technology, which is the current foundation for the majority of passenger planes. Yet if the passenger volume climbs as is anticipated, we simply need new approaches. And economic efficiency also plays a big role. Kerosene already accounts for one third of operating costs. Rising oil prices in the decades ahead would only aggravate the situation. That’s why it is essential for us to start researching and developing alternatives today.”
That is precisely the goal of the collaboration between your two companies. What exactly is taking place?
Zoll: “By 2020 we want to develop hybrid-electric propulsion systems for airplanes and test them on the ground. This will take place for propulsion systems in different power classes, ranging from several hundred kilowatts for small airplanes to several megawatts for regional aircraft. One of the factors providing us with the necessary agility is the integration of this research into next47, Siemens’ startup unit.”
Nüsseler: “We’re examining and developing electrical machines, power electronics, control technology, storage media, and energy generators such as turbines and fuel cells. At our Electric Aircraft system house, which is being developed on the grounds of the Airbus Group in Munich-Ottobrunn, we want to evaluate how all the components work together and test their technical feasibility. In four years we will then decide how we will continue to tackle the subject.”
Where do you see future business for Siemens?
Zoll: “We expect that electrical and hybrid-electrical propulsion systems will become established in small airplanes in the next five years. In the long term they will also become the standard in regional flights involving routes of up to 1,000 nautical miles. We want to establish Siemens as a systems provider of hybrid-electric propulsion technology in aviation and sell perfectly coordinated propulsion components featuring an optimal power/weight ratio.”
What economic advantages does Airbus see with regard to electrically-powered propulsion systems?
Nüsseler: “Hybrid-electric propulsion systems reduce fuel and emissions by as much as 50 percent and, as a result, significantly decrease a plane’s overall operating costs. In addition, electrical propulsion systems are quieter and make it possible to expand takeoff and landing schedules, which have thus far been limited due to noise control reasons.”
With electric cars, battery weight and range have posed the biggest challenges. Do the same issues hold true for aircraft?
Zoll: “In terms of small aircraft, we have already furnished evidence that they can be operated for up to an hour using a purely electrical propulsion system. Thanks to new battery technologies and lightweight design, it will be possible to further expand this range in the future. We also feel that a hybrid-electric propulsion system is the right solution when talking about large aircraft with long ranges and high passenger numbers.”
Nüsseler: “Batteries are still too heavy and occupy too much space in aircraft. Conventional batteries currently have energy densities of around 100 watt-hours per kilogram. They will not be of interest in aviation until they reach around 600 to 1000 watt-hours.”
Zoll: “That’s why we generate energy with the help of a burner generator unit or fuel cells. A battery can contribute additional energy during takeoffs and ascents and then be charged during cruising flight. This approach enables us to ideally combine the benefits of conventional and electrical propulsion systems and we can still expect to meet climate targets.”
Nüsseler: “And economically speaking, this combination is very interesting as well.”
After completing his degree in electrical engineering and computer science at the University of Applied Sciences in Friedberg, Germany, Joachim Zoll joined Siemens in 1989 as an electrical engineer for electrical drives in Frankfurt, Germany. In 1996 he moved to Atlanta, Georgia, where he was director for product management and R&D for Siemens automation and drives. He was subsequently responsible for product management for production machines, sales of motion control systems in China, and was appointed head of Siemens’s crane automation segment and then the company’s machine tools segment before he became head of eAircraft operations in 2016.
After studying mechanical engineering, Martin Nüsseler began his professional career in 1995 when he was appointed a research engineer for failure analyses. He switched to the aviation sector two years later, when he joined Dornier. In 2002 he was hired by Airbus, where he was initially responsible for developing fuselages, including the connections to the landing gear and the wings as well as the integration of all systems. From 2007 to 2009, he headed the development of composite structures and system integration concepts in Toulouse, France. Thereafter, he held a senior management position at Airbus subsidiary Premium Aerotec. In 2014 Nüsseler took over responsibility for the R&D projects for electric and hybrid drive systems at the Airbus Group before he was appointed head of the research and development program for electric and hybrid drive systems at Siemens AG in 2016.