The Aviation Industry Is Preparing for Hydrogen Aircraft
By Yisela Alvarez Trentini
Monday, 16 November 2020
The aviation industry has committed to decreasing greenhouse gas emissions by 50% by 2050. In order to do so, companies are exploring the use of sustainable alternative jet fuels that can help address cost, environmental, and energy security challenges. Among the most promising candidates are hydrogen-fueled aircraft, which could enter the market as soon as 2035.
Due to gasoline-based jet fuel use, commercial aviation faces a variety of challenges. Although jets today are 80% more fuel-efficient per seat kilometer than those from the 1960s, there’s still no practical alternative mode of transport for long-haul flights. Worldwide, flights produced 915 million tons of CO2 in 2019, about 2% of the total human-induced emissions.
Several companies have begun looking for alternative and sustainable fuels that can reduce emissions and expand domestic energy sources, diversifying the supply and generating economic development in rural communities.
Much has been accomplished in the last decade with a wide array of organizations working to support the development of sustainable alternative jet fuels. The Federal Aviation Administration (FAA), for example, runs several programs and activities such as the Commercial Aviation Alternative Fuels Initiative (CAFFI), the Continuous Lower Energy, Emissions, and Noise (CLEEN) Program, and the Airport Cooperative Research Program (ACRP).
Jet fuel meets the current need for safe, efficient, and economic high-speed travel. With a high energy per unit mass, stability, non-volatility, and low toxicity, it’s considered the most feasible fuel we have today. However, several alternatives have been explored with different levels of success.
Among the alternatives considered are nuclear power, ethanol, biodiesel, compressed or liquefied natural gas, and hydrogen.
During the Cold War, the United States and the Soviet Union researched nuclear-powered bomber aircraft. However, neither country managed to create an operational model with enough shielding to protect the crew and those on the ground from acute radiation. The inherent danger of this technology has prevented its civilian use.
Ethanol and biodiesel are great fuel options for ground vehicles and emerged initially as a potentially reliable and clean aviation fuel alternative. However, they were deemed unsuitable for aviation because of their safety, operability, and performance issues. Ethanol is also an aggressive solvent and will attack rubber-type fuel system components, leading to flooding, leaks, and fuel starvation.
Fuel cells and batteries are showing more promise, as we have seen with electric motors from AeroTEC and MagniX. These propulsion systems make less noise and produce zero emissions; however, their range cannot, for the moment, exceed 300 miles and will probably not be ready to power large commercial aircraft for a few dozen years.
Finally, liquefied natural gas and liquid hydrogen have high energy content per unit mass but require two for four times more volume than jet fuel. In 2012, Boeing stretched the fuselage of an airplane to make space for a pair of LNG tanks. While this looked good on paper, safety and design issues mean that the aircraft wouldn’t be ready until 2040 or 2050.
Of all options reviewed, hydrogen could still be deemed viable. And giant aerospace pioneer Airbus agrees.
Hydrogen Fuel Aircraft
In September, Airbus revealed three concepts for their new zero-emission commercial aircraft, the world’s first. The concepts each represent a different approach to various technology pathways and aerodynamic configurations — and could fly the skies as early as 2035.
Codenamed “ZEROe,” all of Airbus’s concepts rely on hydrogen as a primary power source, an idea that could significantly reduce aviation’s climate impact — for good.
The first design is a turbofan (120-200 passengers) with a range of over 2,000 nautical miles. This aircraft could operate transcontinentally and would be powered by a modified gas-turbine engine running on hydrogen. The tanks would be located behind the rear pressure bulkhead. The second design is a smaller turboprop (100 passengers) that could travel over 1,000 natural miles and would be perfect for short-haul trips. The final design is a “blended-wing body” (200 passengers) in which the wings merge with the main body. Its exceptional wide fuselage opens up multiple options for storing and distributing hydrogen.
The ZEROes could be the first climate-neutral, zero-emission commercial aircraft. However, in order for these airplanes to become mainstream, the entire aviation ecosystem would need to rise up to the challenge. For example, airports will require infrastructure to store, transport, and refuel hydrogen, meeting large scale day-to-day operations.
Support from governments would be key to meet these objectives, in particular, to fund research and technology, digitalization, and mechanisms that could help airlines retire older and less environmentally-friendly aircraft.
With the aid of governments and airports, the industry could definitely rise up to the challenge of scaling up renewable energy and hydrogen for the sustainable future of aviation.
About the Author
Yisela Alvarez Trentini is an Anthropologist + User Experience / Human-Computer Interaction Designer with an interest in emerging technologies, social robotics, and VR/AR.