December 12, 2023
By Linnea Ahlgren

How Does A Hydrogen Jet Engine Work?

How Does A Hydrogen Jet Engine Work?© Provided by SimpleFlying

Hydrogen is one of the most promising candidates for future aircraft. Whether it is the use of liquid hydrogen for direct jet engine combustion or in fuel cells, its material properties are extraordinary for use in aviation. Moreover, hydrogen has a near-zero impact on the environment as it does not emit carbon or nitrogen gases into the environment.

Hydrogen has three times more energy density than jet fuel. Unlike the conventional combustion process, hydrogen fuel cells generate electricity through an electrochemical process. The need for continuous electrical power is one of the challenges faced in hydrogen technology.

This article explores the hydrogen combustion process and how it can drive down the carbon dioxide and nitrogen oxide emissions in the environment. While the technology is still in the preliminary phase, it has been tried and tested by large manufacturers, including Airbus.

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A history of hydrogen combustion

The world's first internal combustion engine, constructed in 1804 by Franco-Swiss inventor Isaac de Rivaz, used a combination of hydrogen and oxygen. Tokyo City University has been developing hydrogen internal combustion engines since 1970, and there are buses that run on the technology. It has even already been used to power aircraft.

In 1988, the Tupolev Tu-155 took to the skies as the world’s first experimental commercial aircraft operating on liquid hydrogen. It flew about 100 test flights powered by hydrogen and later liquefied natural gas until the collapse of the USSR in 1991. Now, airplane and engine makers are trying to replicate the task.

Different from hydrogen-electric

A hydrogen internal combustion engine differs from a hydrogen fuel cell. The fuel cells generate electricity from hydrogen and then use that electricity in an electric motor, much like an electric vehicle. Meanwhile, with internal combustion, hydrogen is used the same way as gasoline or jet fuel. Liquid or gaseous hydrogen is burned in a gas turbine engine to generate thrust.

Combustion is a chemical process in which energy is released from a mixture of fuel and air. Proponents of hydrogen say that its wide flammability range and high auto-ignition temperature make it particularly suitable for combustion. The former means it can be used with a lower temperature, creating fewer pollutants, while the latter means less energy loss.

CFM to supply hydrogen engine for A380 testbed

Last year, Airbus announced that it had signed an agreement with CFM International, a 50/50 joint company between GE and Safran Aircraft Engines. The two partners will collaborate on a hydrogen demonstration program using an A380 centered around internal combustion. CFM will modify a GE Passport turbofan's combustor, fuel system, and control system to run on hydrogen.

The test engine will be mounted to the rear of the fuselage, so that readings on factors like emissions and contrails can be measured without interference from the other engines powering the plane running on regular jet fuel.

The program is undertaken as a preparation for Airbus's task to bring a zero-emissions aircraft to market by 2035. Gaël Méheust, President and CEO of CFM, said in a statement announcing the partnership,

“Hydrogen combustion capability is one of the foundational technologies we are developing and maturing as part of the CFM RISE Program. Bringing together the collective capabilities and experience of CFM, our parent companies, and Airbus, we really do have the dream team in place to successfully demonstrate a hydrogen propulsion system.”