Green Infrastructure Critical to Hydrogen Propulsion’s Success

by Chris Kjelgaard (AIN Online) Aerospace manufacturers agree that the ability to produce hydrogen in vast quantities using only renewable forms of energy such as solar and wind power will prove the most critical factor in the aviation industry’s effort to develop the element as a viable, non-CO₂-emitting fuel. In interviews with AIN, at least five major OEMs stressed the need for massive investment to develop the complex infrastructure required to produce hydrogen on an environmentally sustainable basis, and to distribute, store and disburse it as a fuel safely, all of which must happen alongside an effort to develop hydrogen propulsion systems for large and small aircraft.

Only if the development of green hydrogen production and the infrastructure needed to get it into aircraft fuel tanks safely occurs in parallel with OEMs’ development of primary and hybrid-electric forms of hydrogen propulsion can aviation meet its 2035 estimate of being able to replace Jet-A as a fuel for large transport aircraft, say Airbus, Boeing, CFM International/GE Aviation, GKN Aerospace, and Rolls-Royce.

Many activities need to take place in parallel before 2035 to allow for the use of hydrogen—in differing forms depending on aircraft size and mission—as a fuel throughout the aviation industry. Development of hydrogen-propulsion systems and the so-called green hydrogen ecosystem “won’t be a serial process,” said Brian Yutko, Boeing’s vice president and chief engineer for sustainability and future mobility.

The industry needs to understand whether—or in what circumstances and weather conditions—the water vapor produced as exhaust by combusting hydrogen might create persistent contrails that at night could warm the air to foster climate change, according to Glenn Llewellyn, vice president of the Zero Emissions project at Airbus.

Contrails that disperse during the day would not create those “radiative forcing” conditions, but combusting hydrogen produces about 2.6 times as much water vapor as does burning jet fuel, said Alan Newby, director of aerospace technology and future programs for Rolls-Royce. So an important question centers on whether that additional water vapor could create hydrogen-propulsion contrails persisting overnight.

Making hydrogen a viable alternative to jet fuel will require other areas of research and development, according to Yutko. For instance, combusting hydrogen creates NOx formation (and emissions), so researchers must find ways to minimize NOx formation in hydrogen-burning turbine engines’ redesigned combustors. However, hydrogen combustion’s characteristics do “allow you to reduce the amount of NOx produced,” noted Llewellyn.

How the cryogenically cold temperature at which liquid hydrogen gets stored affects the materials the hydrogen contacts also need study, said Yutko. READ MORE

Excerpt from GreenAir Online: US startup regional operator Connect Airlines has announced plans to introduce up to 100 hydrogen-powered ATR 72-600 turboprop aircraft from 2025, once regulatory approval is secured for a new modular fuelling system developed by Universal Hydrogen. The airline, which is aiming to become the world’s first zero-emission carrier, expects to start services this year between the downtown Billy Bishop Airport in Toronto, Canada, and the US hubs of Chicago O’Hare and Philadelphia, initially using a fleet of conventionally-powered Q400 turboprop aircraft, before transitioning to green hydrogen-powered ATRs. Connect, a brand of Boston-based Waltzing Matilda Aviation, sees a resurgence in demand for turboprop aircraft in the US as major operators withdraw uneconomic regional jets from loss-making secondary markets. Through a partnership which includes modest investment by each company in the other, Universal will develop technology through which canisters of hydrogen fuel are loaded directly onto aircraft, requiring no fixed infrastructure at airports, and Connect will introduce the concept into commercial service, reports Tony Harrington.

Connect Airlines CEO John Thomas reported the company was now in the final stages of securing US regulatory approvals for its initial Canada-US flights, and would start with two Q400s formerly operated by UK airline FlyBe, adding up to five more of the type by the end of 2022, and flying up to 30 by the end of 2023. He said these aircraft, which produced 40% lower emissions than comparable-sized regional jets on short haul routes, would be used to build network scale until Universal’s hydrogen propulsion systems were certificated, enabling the carrier to transition to retrofitted ATR 72 aircraft, as well as the Q400s. READ MORE