It’s a world first, says the British airplane engine manufacturer Rolls Royce with the same name as the car, but no other than historical connections: a modern turboprop airplane engine running on green hydrogen. It didn’t fly yet, but it was a successful ‘ground test’ together with the British low-budget airline easyJet.

H2ZERO, as the cooperation was baptized, “is to demonstrate that hydrogen has the potential to power a range of aircraft from the mid-2030s onward”. The test took place at the outdoor military aircraft testing site of MoD Boscombe Down (UK), using a converted Rolls-Royce AE 2100-A regional aircraft turboprop engine.

Both parties announced at the Farnborough aerospace fair in July of this year that they would start ground tests in developing jet engines running on hydrogen.

Electricity by tidal streams

The ‘green’ hydrogen for the tests was supplied by European Marine Energy Center (EMEC) and produced in their tidal test facility on Eday in the Orkney Islands (UK). Established in 2003, EMEC is a leading test center for generating ‘green’ electricity by harnessing the power of waves and tidal streams. With that electricity, ‘green’ hydrogen can be made by electrolysis from water.

“The success of this hydrogen test is an exciting milestone. We only announced our partnership with easyJet in July, and we are already off to an incredible start with this landmark achievement. We are pushing the boundaries to discover the zero-carbon possibilities of hydrogen, which could help reshape the future of flight,” said Grazia Vittadini, CTO at Rolls Royce.

Europe’s second-biggest low-budget airline, easyJet, partnered with American start-up Wright Electric in 2017 to explore short-haul electric commercial flying possibilities. Wright’s electric flagship airplane under development is the Wright 1, a 186-seat airliner with an 800-mile range, targeting entry into service in 2030.

Electric is no real option

But now Chief Operating Officer, Captain David Morgan from easyJet, says that electric flying is not likely for the low-budget airline, which runs aircraft with 190 to 203 passengers throughout Europe. Most developments of battery electric or fuel cell planes focus on the smaller propeller planes for the short haul.

Burning hydrogen in jet engines as a zero-emission fuel is seen by Easyjet and others, like low-budget Hungarian airline Wizz Air, which partners with Airbus for this, as the best option for the long haul in the future.

Jet engine on hydrogen

After having the converted AE 2100-A to hydrogen combustion, a turboprop engine known to equip the Saab 2000 regional airliner, among others, the partners plan a series of rig tests leading up to a full-scale ground test with a Rolls-Royce Pearl 15 jet engine.

The Saab 2000 is a twin-engined high-speed turboprop airplane built by Swedish aircraft manufacturer Saab, which can carry 50–58 passengers and has a range of 1 549 nautical miles (2 869 km).

The Pearl 15 engine was developed especially for the Bombardier Global 5500 & 6500 business jets, enabling top speeds of Mach 0.90 and a range of up to 6 600 nautical miles (12 223 km) on kerosine. This Pearl 15, which is to be modified for hydrogen combustion, is the industry’s most advanced business aviation engine, says Rolls Royce on its website.

Challenge of storing enough hydrogen

It remains to be seen how far a plane like this will get on hydrogen as a fuel, as one of the major challenges is how to store enough of it on board. According to Airbus, hydrogen provides three times more energy by mass than kerosene fuel.

In practice, you would need only 9 tons of hydrogen to provide the same energy as 22 tons of kerosine for an Airbus A320. But as hydrogen delivers 3 000 times less energy by volume, you would need massive tanks unless you compress and cool it to minus 253°C.