The Delft students who built the plane themselves and will send it into the air this year, fervently hope so.

In 2018, the Dutch transport sector according to the CBS 26 billion kilograms of CO2 equivalents of greenhouse gases. And about half of that (49 percent) came from aviation. All the more reason to tackle aviation – which experienced a stormy growth until the pandemic and therefore started to emit more and more greenhouse gases – and make it greener. But how do you do that? TU Delft students have strong ideas about this. They see a great future for the hydrogen aircraft that does not emit harmful substances. And they don’t shy away from demonstrating that such a plane can really ensure that we will board the plane guilt-free in a few decades.

Prototype

The student team – which operates under the name AeroDelft – has already built a prototype of a hydrogen aircraft: Phoenix PT. The prototype must make a flight on liquid hydrogen this year – after test flights on batteries and gaseous hydrogen. The aircraft should be able to travel 500 kilometers on 1 kilogram of liquid hydrogen. With a wingspan of 5.7 meters and a weight of 50 kilograms, it is not yet suitable for passengers. But it is also the prelude to more.

After a hopefully successful test flight on liquid hydrogen in the fall of 2021, the students hope to unveil a significantly larger version of the prototype that can accommodate two people and with a larger tank filled with gaseous hydrogen in the summer of 2022. has to come. And two years later, the students hope to unveil a similar aircraft powered by liquid hydrogen. Because that is where they ultimately want to go, says Koen den Hertog, partnership manager at Aerodelft. “Hydrogen can be stored in two ways, namely in gaseous or liquid form. The former must be stored under high pressure, which means that the storage tank must be very sturdy and therefore heavy. You want to be able to save every kilo in airplanes, which is why with AeroDelft our ultimate goal is to fly on liquid hydrogen.” But that comes with challenges, which is why the team is working towards them step by step. “Liquid hydrogen requires a much lighter tank, but the hydrogen must be extremely cold. Because active cooling costs a lot of energy, smart solutions have to be found to keep the liquid hydrogen liquid.” And AeroDelft is working hard on that.

Revolution

The idea of ​​a hydrogen aircraft is of course not new. “Experiences have been made before, and new systems are still being devised and tested,” says Den Hertog. “But no one has yet developed a successful liquid hydrogen aircraft.” Because although the idea of ​​flying on hydrogen is being played around here and there, at the moment a party is simply needed that provides hard evidence that it is possible. “We hope that if companies and governments see that a group of students can achieve this on a voluntary basis, they will also invest more themselves.”

Another way to fly sustainably: on solar energy. In 2016, this solar-powered aircraft – Solar Impulse – completed a circumnavigation of the globe. A wonderful adventure. But AeroDelft really sees more in hydrogen. “Solar energy is difficult in aviation,” says Den Hertog. “To get enough power you need an enormous surface of solar panels. This was still doable for Solar Impulse; their aircraft was very light and efficient, and did not fly at high speeds; only 6 kW of power was required. However, a Boeing 747 is almost 200 times heavier than the Solar Impulse aircraft, and to get that weight into the air you need an enormous amount of power, much more than can be generated with solar panels. Hydrogen can deliver more power for the same weight, making it much more suitable for aerospace applications, where designers are happy with every kilogram that can be saved.” Image: © Solar Impulse / Stefatou / Rezo.ch.

Long way to go

It is clear that there is still a long way to go. From a technological point of view, there is still much work to be done. And there is still work to be done at the policy level. “At the moment it is not allowed to fly with liquid hydrogen in the Netherlands,” says Den Hertog. “We are working closely with various parties to change this, and the rules and results that come out of this process will be part of new legislation that the Netherlands desperately needs.” In this way AeroDelft hopes to pave the way for the arrival of the hydrogen aircraft in that area as well.

Interested

But are the parties involved really waiting for that? “Of course!” says Den Hertog. “There is an enormous amount of interest in liquid hydrogen. Last year, Airbus announced their own hydrogen project. You also see that there is interest from governments; they also see that aviation must be more sustainable.” And airlines are also watching with interest. “But for them it’s more conceptual; we will probably be a few decades further before we fly on a large scale on liquid hydrogen,” says Den Hertog.

Different experience

For the first passengers who then board the hydrogen plane, the travel experience will be slightly different than they are used to. For example, a direct flight to a distant destination is probably not possible – at least in the early years. “Until the technology is developed far enough, we will indeed see that it makes economic sense mainly for short to medium distances. For long-haul aircraft, with current technology, a hydrogen system is too heavy and therefore too expensive, which means that for long flights, stopovers have to be made to refuel.” On the other hand, the journey is of course a lot greener and in another respect probably a lot more pleasant than it is now. “There is another, unexpected advantage of flying on hydrogen: it is much quieter. The hydrogen is converted into electricity, and the propulsion comes from electric motors. The latter make a lot less noise than the traditional fuel engines, which makes you more comfortable in the plane.”

Here you can see the hydrogen plane that the TU Delft students have developed. It is a small prototype that does not yet offer space for crew and/or passengers. Image: AeroDelft.

Future

It is difficult to estimate when passengers will be able to take a seat in such a quiet aircraft for the first time. In theory, things can go quickly if aviation manages to find the motivation to become more sustainable. “But at the moment it is not realistic to expect that a large part of aviation will fly on hydrogen in ten years’ time,” Den Hertog thinks. “Firstly, a great deal still needs to be developed for this, not only in the technical field, but also, for example, in the field of infrastructure and regulations. Many rules regarding hydrogen in an aircraft simply do not yet exist, and the infrastructure necessary to obtain and transport the enormous amounts of hydrogen does not yet exist. But secondly, we are talking about aviation, where developments are very slow, because of the large investments that are required. On average, it takes about ten years for a new aircraft to be developed, and by the time airlines have replaced their fleet with these new aircraft, we will be ten years further.” However, there are conceivable ways of accelerating cumbersome aviation. “If there is enough pressure from society and politicians actually take strong action to combat climate change, it should be possible with sufficient investments to accelerate the renewal of the fleet enormously.”

It’s future music for now. But it is a tune that AeroDelft already wants to set the tone for. This year, all eyes will therefore be on their prototype that will take to the skies powered by liquid hydrogen. “We hope to show that this is quite possible, and thereby unleash a revolution in aviation.”