How aviation can become ‘greener’.

Friedrichshafen.Snow White, just over 21 meters wide and weighing up to 1.5 tons, is the hope of climate-friendly aviation that landed on Lake Constance in mid-April. HY4 is the name of the experimental aircraft with a fuel cell and battery system, which years later at Stuttgart Airport completed its first flight to another location: 124 kilometers to Friedrichshafen. The HY4 will be on display there from Wednesday to Saturday at the Aero Air Show – as one of many ideas about how aviation can become “greener”.

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The trade fair with 633 exhibitors from 34 countries focuses not on commercial aviation but on general aviation, i.e. above all recreational and commercial aviation. But it is “a large-scale flight test lab for alternative engines such as electric motors,” says a spokesperson for the show.

The list of innovations is long

The Pipistrel Velis Electro, the world’s first certified battery-powered electronic aircraft, and the eMagic One, an electronic wing vertical tandem take-off aircraft from Germany, which looks like a mixture of UAVs and sports aircraft, can be found on display on Lake Constance. The list of innovations also includes many other electric and hybrid aircraft, sustainable drivetrains and battery systems.

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But for now, the role of electronic aircraft will likely be limited to small aircraft such as private aviation, says Markus Fischer, head of the aviation department at the German Aerospace Center (DLR). In order to propel a commercial airliner over thousands of kilometers, batteries would have to have a much higher energy density – and they would be very heavy. “As things stand today, the majority of an aircraft’s weight will be determined by the batteries,” Fisher says. So far, this basic issue is not expected to change soon.

Sustainable fuels are particularly promising

On the other hand, sustainable fuels, referred to in aviation as sustainable aviation fuels (SAF), are promising. Until now, it was mainly made from organic waste such as used cooking oil or meat and fish waste. “It works,” Fisher says. But the quantity is very limited so far. “

Additionally, SAF is three to seven times more expensive than conventional kerosene, Fisher says. In accordance with the will of the EU Commission with its “Fit for 55” initiative, 2% of aviation fuels should be sustainable by 2030. “We think five percent is also possible,” Fischer says. However, the biggest hurdle is providing an adequate amount. The regular service will surely be served first, before the young ones, for example general aviation, come into the feeding trough.”

By 2030, the SAF’s stake in Airbus should be 100 percent

For example, aircraft manufacturer Airbus is increasingly dependent on the Sudanese Armed Forces. According to the company, up to 50 percent of SAF can be added to conventional kerosene in all modern Airbus aircraft, and the percentage should be 100 percent by 2030. “On short and medium-range routes, sustainable jet fuel is only a temporary solution,” Airbus said. “. Subsequently, hydrogen technology could enable zero-emission CO2 flights there.

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New fuels: Aviation must become more sustainable by 2045

Germany wants to be climate neutral by 2045. This requires new engines and technologies for air traffic as well.

DLR expert Fisher also sees good opportunities for hydrogen engines in this size class. “There’s a tendency to use it in planes that don’t fly that far — maybe 1,500 kilometres.” In order to get a lot of energy in a small space, hydrogen must be stored in tanks as a gas under high pressure or as a liquid stored at low temperatures, Fisher says. This requires relatively heavy tanks.

H2Fly wants to conduct test flights with Dornier aircraft by 2025

The operator of the HY4 experimental aircraft, Stuttgart’s H2Fly company, wants a hydrogen-electric Dornier aircraft with 40 seats in the air for test flights by 2025. “Ultimately, the project should result in the production of a series of passenger aircraft,” says a company spokesperson. The target range is about 2,000 kilometers, for example, to create flights from Warsaw to Paris.

According to the company, the biggest problem is adapting the drive to this size. There are suitable products from the automotive industry for the 120 kW fuel cell in the HY4 test plane. For Dornier 328, the required power is more than twelve times higher – about 1.5 megawatts. A spokesperson for the company says its parts are “very few at the moment, especially not for aviation”. “That’s why we’re doing real pioneering work here.”

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As Fischer, a DLR expert, sees, there is no short-range alternative to large jets in fuel cells. “It’s a long way to go. But it makes sense to start on a small scale and show the feasibility.” In order to do this in Lake Constance, operators of the HY4 test plane brought their ‘green’ hydrogen tank options from Stuttgart.

It also works well with conventional combustion engines

But even if many sustainable engines linger: After the corona-related slump, the aerospace business in general is also doing well with conventional combustion engines. At the end of 2021, deliveries were back to numbers before the pandemic started, a spokesperson for the International Industry Association, the General Association of Aviation Manufacturers, said.

A spokesperson for the trade fair said that digital networking in times of Corona in particular has led to an increased need to meet in person during important negotiations. Considering airlines’ dwindling flight schedules, “only business aviation provides the necessary commute for people to meet.” After all, it takes several days to get from Oslo to Palermo using other means of transport.

RND / dpa

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