Carbon-free flights promised 'within two years

An aviation company plans to run commercial flights using an electric engine that creates no carbon emissions by 2025.

ZeroAvia has flown nine test flights with its hydrogen-electric engine at Cotswold Airport, near Cirencester.

The only emission created by the engine is water.

How does it work?

The Gloucestershire-based company are moving much faster because they are not designing an entirely new aircraft.

ZeroAvia is working on the Dornier 228, a conventional 19-seater plane that has two propellers, usually powered by kerosene.

One of these has been replaced by an electric engine, and the electricity is generated on-board using a hydrogen fuel cell. For the testing period, the other engine remains fuelled by kerosene, in case of failure.

But once the technology is proved, both engines will run on electricity from the hydrogen fuel cell.

Only the new engine needs to pass safety tests, and the company is working with the Civil Aviation Authority to achieve certification.

Test pilot Jon Killerby flew the aircraft and told me that once airborne, they have managed without the kerosene engine.

"We can throttle right back on the conventional engine,"

Is it really 'green'?

Hydrogen fuel cells are not new, and have been widely used in cars and trucks.

They use a chemical process called "reverse hydrolysis" which combines hydrogen with oxygen and creates heat, water vapour and, crucially, electricity.

So the on-board engine creates no greenhouse gases.

But what matters is where you get your hydrogen.

How big, how far?

It is not a big plane.

The Dornier 228 will carry about 12 passengers with the hydrogen engine on board.

It can fly about 250-310 miles (400-500km),

That would get you from Bristol Airport to Newcastle, or London to Paris.

By 2027, the company plans a larger hydrogen-electric engine which would power bigger aircraft. This could carry around 50 passengers and go nearer to 620 miles (1,000 km).

What are the problems?

"Like all technologies, there are challenges," smiles Prof Mays.

"Making it, transporting it, and storing it."

The aviation industry needs to build an entirely new infrastructure. Hydrogen production centres, a network to get the fuel to airports, storage at airports, the lot. And hydrogen is very different from conventional kerosene.

Hydrogen takes up a lot of space. To carry it all manageably, the gas is compressed to 350 or 700 times atmospheric pressure.

Even then, it takes up more space than kerosene. If you want to transport it as a liquid, you must first chill it to 253 degrees below zero.

So exactly where to make it, how to move it around and store it are all being examined now by airports and aerospace firms.

Prof Mays put it like this: "You can fly using hydrogen as a fuel, but it is not optimised, not super efficient yet, and the infrastructure is not there yet."

Source:bbc news

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