Thierry Dubois Ground-support equipment suppliers make fast progress toward hydrogen use, but OEMs are still reviewing their options.
Thierry Dubois
Ground support equipment, which has thus far relied on fossil fuels and batteries, may lead the way for hydrogen use in aviation. Credit: APS Aviation Parts Service
When Airbus senior executives need to choose the design for a hydrogen-powered aircraft in 2025, they will be reaping the benefits from the knowledge and experience the entire European industry will have gained.
Airbus engineers themselves will have studied various configurations in depth, and by then the company will have test-flown a liquid-hydrogen tank.
The European Union Aviation Safety Agency is currently training its certification experts and hiring hydrogen specialists. Startups are making progress on innovative ideas, such as improving the efficiency of the refueling process despite the tendency of liquid hydrogen to vaporize. New skills from outside aviation may be harnessed as well, with sea transport about to make strides in such propulsion systems.
Two segments in commercial air transport show contrasting stages of readiness. Aircraft handling at airports looks close to the entry-into-service phase, with comprehensive testing in the offing for hydrogen-powered ground support equipment (GSE). Meanwhile, the manufacturers of engines (or motors, should they be electric-powered) have just begun to clarify their intentions and identify the challenges ahead.
The Hydrogen for Airport Handling project is aimed at testing the use of hydrogen-powered GSE for the entire aircraft turnaround process. It is part of the broader H2 Hub Airport demonstration program, launched by Paris airports operator Groupe ADP with partners such as Airbus and Air France (AW&ST July 26-Aug. 8, p. 38).
Groupe Europe Handling (GEH), an aircraft handling services provider, has created the Hydrogen for Airport Handling consortium with five other companies. Four of those partners are manufacturers—Airmarrel (baggage loaders), Charlatte Manutention (baggage cart tractors), Goldhofer (towing vehicles or tugs) and Guinault (ground power units or GPU)—and the fifth, Engie, is an energy supplier. GSE is already at a high technology readiness level, between 6 and 9, according to its promoters.
Testing is scheduled to begin during the winter of 2022 and continue into early 2023 at Paris Charles de Gaulle Airport. By integrating a full suite of vehicles into a realistic environment, “we are going to collect data, especially in fuel consumption,” says Mildred Dauphin, GEH’s sustainable development manager and consortium coordinator. “The manufacturers are going to improve their fuel cells.”
The vehicles will use gaseous hydrogen. While the technology has been applied to cars and buses, usage will be different at an airport. Typically, maximum power will be needed for only short periods.
There are multiple hoped-for benefits of hydrogen propulsion, as opposed to battery power. Battery charging requires cable installation and much more land surface than a hydrogen gas station. The problem of cooling down batteries during the charging process—for safety and efficiency—is eliminated with the use of hydrogen fuel cells.
For a high-power GSE system, a fuel cell is also more suitable than batteries, says Dauphin. GEH already operates electric equipment including conveyor belts, baggage tractors and light loaders. The company manages roughly 1,000 vehicles and other pieces of GSE, with electric-powered equipment and aircraft accounting for 40% of the total.
Moving to ecologically produced hydrogen for the most powerful equipment will cut GEH’s CO2 emissions by an estimated 75%.
The Hydrogen for Airport Handling project—on which a combined 43 employees from all six partners are working—is intended as a holistic approach. Consequently, training modules for drivers and operators will be developed. Engie is looking for synergies on the infrastructure front between hydrogen gas stations on the airport’s air and land sides. As a result of these developments, the consortium will likely lead and possibly pave the way for wider hydrogen use in aviation.
Meanwhile, aircraft and engine manufacturers are still at a crossroads. Airbus is considering fuel cells distributed in wing pods, among other options. Safran is ruling out that option. “Fuel cells are not at the right performance level to be considered for 2035-40,” Safran Electrical & Power then-Chief Technology Officer Stephane Cueille said in August.
Therefore, the engine-maker is counting on gas turbines. “Ninety percent of the technology will be the same [for conventional fuel and hydrogen],” Cueille said. For example, the GE Aviation/Safran Revolutionary Innovation for Sustainable Engines (RISE) open-fan technology demonstration program includes that option.
Modifications can be expected at the engine’s combustor and fuel-system levels. But the farthest-reaching changes will be seen in the aircraft’s fuel system, including tanks, Cueille said. “The main challenges will result from the necessity to handle liquid hydrogen at -253C (-425F), vaporize it, heat it and compress it,” he said.
Using hydrogen will involve an intense endeavor to cut fuel consumption. “At issue are the volume of hydrogen on board, its cost and availability,” Cueille said.
Safran executives are seeing hydrogen as a complement to more conventional fuels. It can be used in its cryogenic form or as an ingredient for synthetic kerosene, also known as power-to-liquid or e-fuel. Sustainable biofuels may suffer because their production will be limited but demand for them will be strong, Safran executives say.
In addition, they note that “hydrogen can only be used for flights of a few thousand kilometers because of the size of the tank.”
Rolls-Royce, whose engines primarily power long-range aircraft, is investigating the feasibility of gas turbine engines that burn hydrogen in a modified combustor, the company says.
