THE REALITY OF ZERO-EMISSION FLIGHTS

HAVE THE LATEST INNOVATIONS IN AVIATION FUEL, ELECTRIC BATTERIES AND HYDROGEN-POWERED AIRCRAFT LEAD US ONE STEP CLOSER TO TAKING TO THE SKIES SUSTAINABLY? WORDS: GRAEME PATON

What steps are being taken to make flying more green?

The short-term focus will be on the fuel rather than the plane. Airlines are investing heavily in ‘sustainable aviation fuel’ — kerosene mixed with renewables and waste — to cut levels of carbon dioxide (CO2). In September, British Airways operated its first flight between Heathrow and Glasgow using fuel from recycled waste cooking oil, cutting overall CO2 by 28%.

But a more radical solution is needed. Several companies, such as EasyJet, hope to fly full-sized, battery-powered electric planes by the end of the 2020s. However, pure electric flights might not be feasible for decades, if ever, because of the size and weight of batteries required to generate the necessary thrust.

Which companies are leading the innovations?

In recent years, attentions have turned to hydrogen, which packs a huge amount of energy — more than 100 times that of lithiumion batteries — while producing zero CO2 from the engine. In the UK, development has been led by ZeroAvia, a US-UK startup. In 2020, it operated the world’s most advanced hydrogen-powered flight. Backed by a £12.3m UK government grant, the company tested its hydrogen fuel cell system in an adapted six-seater Piper M350 light aircraft on a 19mile flight from Cranfield Airport in Bedfordshire.

Next, the company is planning to develop a hydrogen-electric propulsion system that can power a far larger 19-seater. British Airways is among the airlines investing in ZeroAvia. Airbus, the European aviation giant, is also developing its own hydrogenpowered aircraft, the ZEROe, fuelled by liquid hydrogen. Three design concepts have been drawn up, with backing from airlines such as EasyJet.

When will we be buying a ticket for a flight on a zero-emission plane?

It’s a possible reality for very short routes within three years. Loganair, which mainly operates between the Scotland and its islands, is part of a UK government-backed consortium, Project Fresson, developing a hydrogen fuel cell-powered plane. It could enter service by 2024. Large hydrogen aircraft — carrying 100 passengers plus — on longer routes aren’t likely to be possible until well into the 2030s.

Airbus ZEROe is unlikely to produce results until 2035 at the earliest, mainly because the fuel cell and surrounding components are heavy and complex, while the hydrogen itself requires bulky storage tanks. This is relatively straightforward on short flights but can cause a major challenge for larger commercial aircraft where more hydrogen is needed.

Will the price of air travel be cheaper?

The move to hydrogen — or ultimately battery power — should, in time, produce cheaper and quieter aircraft. Estimates suggest that hydrogen planes will be around a third cheaper to operate than kerosene aircraft because of the density of the fuel combined. Furthermore, they have far fewer moving parts, which cuts down on costly maintenance. But savings will be slow to reach customers: in the short term, the huge price of developing the technology, rather than relying on decades-old jet engines, will probably lead to higher initial costs.

Will planes of the future be truly ‘zero-emission’?

Potentially. Significant hurdles to overcome include aircraft production, which is hugely carbon-intensive. Last year, Boeing claimed it had achieved ‘net zero’ in its worksites but only by offsetting some of its emissions, a practice condemned as ‘greenwashing’ by Greenpeace. Additionally, most of the world’s hydrogen, which will be needed to propel future aircraft, is produced by reforming methane from natural gas, a fossil fuel, which produces CO2. Efforts are underway to develop ‘green hydrogen’ using an electric current from a renewable source to convert water into oxygen and hydrogen, but the technology is still largely in its infancy.