Green Skies: The Leap Towards Hydrogen Powered Flight

This blog is about the latest technologies and conventions being discussed about hydrogen powered flight.

The aviation industry with its ever-growing demand makes up around 2% of global CO2 emissions. According to the Federal Aviation Administration (FAA), this percentage is expected to rise in the future. Thus, a lot research & development has been done over the years to make the aviation industry sustainable.

In the ongoing push for cleaner, low carbon emissions aircraft, engineers have in recent times explored a wide range of technology options. These include enhancing existing turbine technology, using more sustainable fuels and extensive research has been performed on hybrid-electric battery systems.

However, since the COVID pandemic aviation industry has been hit the hardest. The balance of power swung firmly towards a more sustainable & futuristic energy carrier, hydrogen.

Whilst interest in hydrogen-powered aircraft has been growing for some time, the decisive sign came recently in September 2020, when the world’s biggest aircraft manufacturer, Airbus announced that hydrogen fueled propulsion systems would be at the heart of a futuristic goal to introduce a new zero-emissions commercial aircraft by 2035.

The Airbus CTO unveiled three concepts for the world’s first zero-emission commercial aircraft. These concepts offered a glimpse of what the future of aviation might look like. In a mind-grabbing headline, the Airbus CTO, Grazla Vlttandni said:

”Hydrogen has the same energy level as kerosene generating the same type of performance and range with almost one third of its weight.”

The three futuristic concepts revealed by Airbus comprised of a turbofan, turboprop and blended-wing body aircraft. The turbofan aircraft will be powered by a modified gas-turbine engine running on hydrogen. The design aimed at a 2000 nautical-mile range along with 120-200 passenger seats. Moreover, the turboprop aircraft powered will also be powered by hydrogen with a range of 1000 nautical miles. The most striking design is the new look blended-wing body aircraft design which uses similar propulsion as the turbofan aircraft. This design aimed at revolutionizing the airframe design of the future aircrafts.

The Airbus chief technology officer Grazia Vittadini at the ZEROe Airbus online event said that hydrogen is the next most promising route to zero emission aviation. This is mainly due to its compelling energy density which can eventually reduce 50% of carbon emissions produced by the air transport industry.

However, there are some big challenges which lies ahead of this compelling concept. Firstly, the volume of hydrogen is 4 times greater than kerosene. This means that the aircraft fuel tank and its integration within the aircraft has to be re-designed entirely.

There are two types of hydrogen forms considered, the gas form and liquid form. The liquid-hydrogen offers lower energy per unit volume than conventional aviation fuels. However, lightweight vacuum-insulated tanks will be required to maintain its temperature, due to its boiling point of 20 Kelvin.

On the contrary, gas state of hydrogen carries a larger weight penalty and the fuel tanks have to be built with adequate strength to withstand high pressures of 250 to 300 bar. However, considering the benefits of hydrogen-powered engines, Phillip Ansel, director of the NASA funded center of High Efficiency Electrical Technologies for Aircraft at the University of Illinois at Urbana Champaign, says that the added external surface area which is needed to accommodate the bigger hydrogen tanks, which result in higher aerodynamic drag, can be minimized by carefully designing other components of the aircraft.

The Airbus rightly came to a conclusion recently that their ambitious E-Fan X, the joint Airbus/ Rolls-Royce hybrid electric aircraft project should be scrapped. This was because hydrogen holds key advantages over batteries specially when it comes to aviation. Thus, the Vice President of Airbus, Glenn Llewellyn believes that hydrogen has cemented its place at the top of low carbon pecking order.

Meanwhile, as Airbus ambitious plans are number of years away from reality, ZeroAvia, a United States aviation startup became the first company to put a commercial scale hydrogen powered passenger aircraft in the skies. The project is known as HyFlyer.

The HyFlyer project was recognized as a landmark moment for low carbon aircrafts. The Piper M-Class aircraft was retrofitted with hydrogen fuel cell powertrain. The hydrogen fuel cell combines hydrogen from the hydrogen fuel tank fitted in the aircraft wings and oxygen from the atmosphere to generate electricity and water. The electricity produced powers the aircraft electric motors, which in turn power the propellers and water is disposed from the exhausts. The aircraft took flight from the R&D base at Cranefield airport in the United Kingdom. The HyFlyer aims to be certified for commercial operations for a 10-to-20-seater aircraft with a 500-mile range by end of 2023.