Airbus believes hydrogen-powered planes are well-suited to cutting emissions from intra-continental air travel, but longer-range aircraft will rely on sustainable aviation fuel to reduce their environmental impact, a company spokeswoman tells Hydrogen Economist.

Last September, Airbus unveiled three ZEROe hydrogen-powered concept planes that it claims could enter commercial service in 2035. The turboprop concept could fly up to 100 passengers to a range of c.1,000 nautical miles, while the turbofan and blended-wing configurations would have double the capacity and range.

Airbus revealed another potential design in December in which a plane would have three, eight-bladed engines on each wing. Each pod would be a standalone propulsion system including a propellor, electric motors, hydrogen fuel cells and liquid hydrogen tank.

“We aim to achieve a cost of acquisition and operation that is highly competitive to other aircraft of comparable size and range” Airbus

An Airbus spokeswoman tells Hydrogen Economist the firm continues to develop demonstrator programmes to test hydrogen fuel cell and hydrogen combustion technologies and that these studies “are progressing well” but declined to provide further details. “At this stage, Airbus is focusing on short- and medium-haul travel. It is likely that long-range aircraft will still require sustainable aviation fuel, potentially made from hydrogen-based sources.”

Competitive dynamics—not because larger aircraft designs are impossible—led Airbus to create hydrogen plane concepts with small passenger capacities, says Dragan Kozulovic, professor for flight propulsion at the Hamburg University for Applied Sciences. “There is not a market for new large-scale planes—it would be very difficult to break the dominance of existing aircraft,” he says.

In long-range conventional passenger planes, 30-35pc of the weight is fuel, while for mid-range this figure falls to 20-25pc. Hydrogen-powered planes would need to achieve similar ratios, says Kozulovic.

Commercial viability

Of the three concepts, Airbus increasingly sees its turboprop as the most viable. Kozulovic believes likewise: “It is the smallest plane and will have the lowest technological, development and safety risks. “It is much cheaper to develop mid-range aircraft than larger airliners. Opting for the turboprop would be most balanced decision Airbus could make.”

The blended-wing plane has more space for hydrogen and passengers and the concept “is much more scalable than the other two”, Jean-Brice Dumont, Airbus executive vice president of engineering, said on a company webcast.

Blended wing concepts are not new but have never made it into commercial production due to various intrinsic disadvantages. These include the difficulty for passengers to disembark in emergencies, a consumer preference for window seats and discomfort felt by passengers far from the centre line of the aircraft.

Airbus, which says it will make a final decision on its preferred technologies and aircraft configurations by 2025, envisages using hybrid modified gas turbine engines that would burn hydrogen and also have hydrogen fuel cells to provide electrical power.

“Technologically, hybrid engines are possible, but it would add complexity and operational costs—nobody wants to have two propulsion systems on an aircraft,” says Kozulovic. “Buying and maintaining dual systems is more expensive and the additional complexity also increases the risk of failure.”

-253°C – Temperature hydrogen turns into liquid

For any given amount of energy, hydrogen weighs one-third as much as kerosene but occupies four times the volume. Therefore, hydrogen tanks will be built into the fuselage, which will have to be longer and wider, causing more drag and lowering fuel efficiency.

Airbus acknowledges it has yet to solve how to equip aircraft with sufficiently large liquid hydrogen storage tanks, which are bigger and heavier than their kerosene counterparts. Hydrogen becomes a liquid at minus 253°C.

“Cooling to cryogenic temperatures is very demanding. The tanks have to be perpetually cooled and remain under high pressure. [But] the development of this technology has been going on for decades. Airbus is not starting at zero,” adds Kozulovic.

Bringing zero-emission aircraft into service will require billions of euros in investment, according to the company spokeswoman who declined to comment on whether hydrogen planes would command a price premium. “We aim to achieve a cost of acquisition and operation that is highly competitive to other aircraft of comparable size and range,” she adds.

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Author: Matt Smith