Rolls-Royce tests a jet engine running on hydrogen

A small aircraft jet engine in a windswept corner of a military site on Salisbury Plain, is undergoing tests that could one day lead to huge changes within the aviation industry.

The engine itself is almost completely conventional. It is a Rolls-Royce AE-2100A gas turbine, a design used widely on regional aeroplanes around the world.

What is wholly unusual about it is the fuel being used. This is the first time a modern aircraft engine has ever been run on hydrogen.

Devoid of bodywork, with its intricate wiring and pipework exposed, it sits securely fastened to a sturdy test rig, while engineers cluster around an array of screens in the control room, a safe distance away.

The tests are being carried out by Rolls-Royce, in partnership with the airline easyJet.

The immediate aim is a simple one – to show that it is possible to run and control a jet engine using hydrogen fuel, rather than conventional aviation fuels.

In the longer term, the plan is for hydrogen power to play a major role in allowing the aviation industry to continue growing, while cutting climate change emissions dramatically.

“The reason we’re looking at hydrogen is really the drive for Net Zero,” explains Alan Newby, director of aerospace technology at Rolls-Royce.

“Normally we would run this thing on kerosene. Kerosene is a hydrocarbon and therefore produces carbon dioxide when it burns.

“The beauty of looking at a fuel like hydrogen is that it doesn’t contain any carbon and, therefore, when it burns it produces no CO2”.

The project is being supported by easyJet, which has contributed several million pounds towards the initial trials.

The company believes that hydrogen power offers the best route to reducing emissions from short haul aviation.

“We started a few years ago looking at what might power the aircraft of the future,” explains David Morgan, easyJet’s chief operating officer.

“We looked at battery technology, and it was quite clear that the battery technology was probably not going to do it for the large commercial aircraft that we fly.

“We’ve come to the conclusion that hydrogen is a very exciting proposition for us.”

The advantage of hydrogen over batteries is that it provides much more power per kilogram. Batteries are simply too heavy to power larger planes.

Yet hydrogen aviation remains a very long way off. The tests carried out so far have simply shown that a jet engine using hydrogen can be started up and run at low speed.

But to go from there to building a wholly new engine, capable of powering a passenger aircraft safely will take a great deal more research – and significant investment.

The aircraft themselves will also need to be redesigned. Hydrogen, even in liquid form, takes up about four times as much space as the kerosene required to fly the same distance.

To make it into a liquid in the first place, it needs to be cooled to -253C. Then, before being burned, it must be turned back into a gas.

“There’s a big change from the aircraft point of view,” says Alan Newby at Rolls-Royce.