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quietus [soylentnews.org] writes:

European airplane maker Airbus and a 50/50 joint partnership between General Electric (GE) and Safran Aircraft Engines are going to equip an A380 superjumbo with a hydrogen engine [airbus.com], by 2026. The plan is to go the cryogenic route with hydrogen: using its liquid form at -253°C (-425°F), and burning it directly [airbus.com] in a GE Passport turbofan.

The modified A380 will keep its 4 conventional turbines, with an additional fifth being the hydrogen-powered one.

The number of technical challenges are large. Under the plans, 400kg of liquid hydrogen will be stored in four tanks at minus 253 degrees Celsius. A new cryogenic distribution system will need to be developed. The hydrogen will also need to be converted into a gas before it is burnt. The gas burns at a much higher temperature than conventional jet fuel, so special cooling and coating materials will also need to be developed.

The modified GE Passport jet engine [ge.com] needs a complete overhaul of its combustor, fuel system and controls system to make them compatible with liquid hydrogen fuel. The group picked the Passport because of its size, advanced turbomachinery and ability to operate at the appropriate pressures and temperatures for the flight platform. As the liquid hydrogen needs to be vaporized into gas to be used as fuel, certain parts of the engine could see temperature differences of some 1,500 degrees Fahrenheit.

Liquid hydrogen can only be used [safran-group.com] for flights of a few thousand kilometers because of the size of the tank, and must therefore always be supplemented with other types of fuel. In this form, hydrogen will hence not compete with other sustainable liquid fuels, but rather complement them.

The second option for employing hydrogen as a directly burned airplane fuel is to convert it into synthetic kerosene by combining with captured CO₂. This approach, called "synthetic fuels", "electrofuels" or "Power-to-Liquid," is technically less complicated, and has the advantage of being compatible with current aircraft and existing logistics -- but that's not what is being tested here.

Another alternative, sustainable aviation fuel (SAF), made from renewable biomass and waste products, has also started to take off: Last October, Etihad Airways employed a fuel blend containing SAF among an array of existing solutions on a regularly scheduled long-haul flight from London to Abu Dhabi. That flight produced carbon emissions 72% below [etihad.com] those of an equivalent flight two years earlier. In December, United Airlines operated the world’s first passenger flight using 100% SAF [aviacionline.com] in one of its CFM LEAP-1B engines.

The A380 was chosen for its size: allowing plenty of room for the tanks, cooling and testing equipment. A commercial product will be much smaller. Airbus said last year it would likely initially produce a regional or shorter-range aircraft (100 passengers, range 1,000 nautical miles).

Engineers at Airbus are working on several different zero-emission concepts [airbus.com], all of which rely on hydrogen as their primary power source. Sabine Klauke, chief technology officer, was quoted in the Financial Times as saying that the company would decide by the end of this decade which route to take.

Airbus aims to have the first of these aircraft [iatanews.com] in service by 2035.

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