Environmentally-friendly air travel continues to grow and grow

Environmentally-friendly air travel continues to grow and grow

September 10, 2021

When it comes to innovation, the sky's the limit

Green air travel has been growing in importance in recent years. The movement began in earnest around 2010, with the announcement of around 20 new global projects focusing on electric and hybrid propulsion techniques in areas including general aviation, large commercial travel, regional and urban air taxis. By 2016, the electric propulsion R&D boom began, with several dozen new projects being launched and startups emerging from stealth mode. Fast forward to 2021, and approximately 280 such aviation projects are underway around the world, with about 85 percent of them in Europe and North America. And the upward trend looks set to continue.

The first half of 2021 saw 11 additional projects in Europe, North America, South America and Israel. A shift is also visible away from electric and hybrid propulsion techniques and towards hydrogen propulsion, which accounted for 36% of projects announced in 2021.

Electrically-propelled aircraft continue to gain momentum

The number of electrically-propelled aircraft has risen sharply over the last decade, amounting to 61 percent of total development in this space. Our latest Think:Act Aircraft Electrical Propulsion – Onwards and Upwards charts recent developments and investigates how the aviation and aerospace industries stand to change. The interactive map below allows you to discover which countries are at the forefront of research and development, who the key players are, and what major projects are underway.

"The focus on electrically propelled developments has partly given way to a focus on hydrogen since 2019, the latter accounting for around a third of new projects in 2021."
Portrait of Robert Thomson
Partner, Managing Partner United Kingdom
London Office, Western Europe

Urban air taxis continue to dominate

Currently, more than 100 projects are taking place worldwide to develop and test the urban air mobility (UAM) ecosystem. Urban air taxis represent around 40 percent of all the new publicly-known developments, putting them ahead of other categories of aircraft. The initial expansion in this space can be attributed to key aerospace players, such as Boeing and Airbus. The first successful test flight of an autonomous passenger air vehicle (PAV) prototype was in January 2018. The A3 Vahana was Airbus's first PAV to take flight, followed shortly afterwards by the four-person passenger CityAirbus. These vehicles are designed to fly autonomously , however the first commercial flight, set to take off in 2023, will be guided by a pilot until the air traffic space gains maturity in the sector.

The year 2021 has seen two innovations from Brazil-based civil aircraft manufacturer Embraer. Pulse Concept and Eve are both passenger electric vertical take-off and landing aircrafts (VTOLs) that can carry four to six passengers. The first flight is planned for 2026.

General aviation is close behind

General aviation accounts for around 100 projects globally, or 37 percent of the total number of projects in our interactive map. Together with urban air taxis, it dominates the area of fully-electric propulsion. This is not surprising: Not only are smaller developments easier to fund and test, but current electrical systems technology still favors lower power and shorter-distance flights. However, Solar Flight Inc. has made great strides in solar-powered aircraft over the last decade, with the goal of seeing solar-electric take flight in the near future. Despite capturing the world's imagination with the hugely successful Solar Impulse flights, solar power at scale remains in its infancy - some element of solar power, potentially hybridised with other power sources, may see further interest going forward for smaller aircraft.

A year of partnerships

2021 has also been a year of partnerships. Among the many joint projects announced in the first half of 2021, a partnership was established between California-based electric aircraft manufacturer Joby Aviation , airline carrier JetBlue Airways, and Signature Flight Support, with the goal of accelerating the commercialization of clean aviation. In the short term, the partnership will strive to establish a framework for carbon credits, to pave the way to using sustainable energy in the aviation industry. The partners recognize that hydrogen propulsion technology is still at an early stage of its development, but they believe that it will be key in speeding up the industry's transition to commercialized green air travel.

"Urban air taxis continue to dominate the scene, representing about ~40% of all developments mapped"
Portrait of Robert Thomson
Partner, Managing Partner United Kingdom
London Office, Western Europe

The promise of hydrogen

For the first time, we now include hydrogen-propelled aircraft in the Roland Berger Sustainable Aircraft Database. Even as the growth in the number of battery-electric and hybrid-electric projects waned, hydrogen has taken centre stage in the past year, with a number of new projects announced including Airbus' ZEROe concepts, GKN's H2GEAR and ZeroAvia's 50+ seat engine development programme.

While the opportunities for leveraging liquid hydrogen as fuel are promising, significant challenges remain. These obstacles need to be overcome before liquid hydrogen can be widely adopted by the aviation industry. Since hydrogen has low volumetric energy density, aircraft would need to carry a large volume of fuel compared to current jets, which poses a significant design change. In addition, cryogenic temperatures are required to contain liquid hydrogen, which would add to the design complexity. The shape of the tank (spherical, cylindrical or hybrid ) is also critical for optimizing volumetric efficiencies.

The safety concerns around hydrogen technology are even more pressing. Hydrogen can easily seep through containment lines, and leaks can be extremely challenging to detect and rectify. Another risk with potential hydrogen leaks is that hydrogen can deprive the environment of oxygen if released in large quantities, which could be lethal in the event of an internal leak.

Nevertheless, the potential for hydrogen propulsion is significant as it offers a zero carbon (if not True Zero) propulsion option, as demonstrated by the enthusiasm shown by new entrants and incumbents to overcome these challenges.

Giving future passengers a say

The general public also have a role to play, especially when it comes to urban air taxis. Airbus UTM, a division of Airbus's Urban Air Mobility Unit, recently published results from a preliminary study on UAM public acceptance. Of the 1,540 people surveyed, 44 percent indicated that they support UAM deployment. Top concerns included the safety of individuals on the ground and noise pollution.

The study shows that geographical or practical necessity and mindset may be key factors in determining how fast and how widely urban air taxis are adopted. Engaging and educating the public may be necessary to achieve widespread acceptance; in the Bavarian city of Ingolstadt , for example, citizens have been promised an active role in feasibility studies as part of the city's ongoing UAM Initiative.

The sky is the limit for innovation

Electrically-propelled aircraft and their associated ecosystem are making progress, but are not yet mature. The regulatory landscape is also still taking shape. However, this uncertainty does not appear to deter established players and startups from venturing into this space. Besides Airbus and Boeing, a range of other players are active in the sector, such as Kitty Hawk, which was acquired by Joby Aviation recently.

While the companies mentioned above are based in the United States, similar innovation is seen in other countries around the globe. For example, Germany's Lilium and Volocopter aim is to design a five-seater and a two-seater air taxi respectively, for commercial use. Similarly, the Russian team Hoversurf is building an eVTOL capable of seating four passengers, which can be piloted autonomously. While the majority of innovations over the last decade have focused on battery-powered aviation, US startup Alaka'i Technologies Corporation's Skai is focusing on hydrogen-propelled aircraft, with the goal of launching an aircraft that can travel for up to four hours with autonomous capabilities.

But it doesn't stop at air taxis. Terrafugia, a Massachusetts-based and Chinese-owned startup, is building a flying car that seats two passengers and is a hybrid electric road vehicle combined with a pusher-style propeller-driven plane. Although we currently seeing a multitude of different green aviation developments, they are all united around the same goal: To create more sustainable means of aviation .

Further readings
Portrait of Robert Thomson
Partner, Managing Partner United Kingdom
London Office, Western Europe
+44 20 3075-1100