Much has been said about the potential of hydrogen conversion for “green” aviation. Hydrogen, in gaseous form, has a much higher energy density than conventional lithium batteries, offering a direct route to reducing carbon dioxide emissions from aviation. However, as the size of the flying vehicle increases, so do its emissions. For long-range flight, compressed gas storage systems are not sufficient. Hydrogen must therefore be converted into liquid. Liquid hydrogen systems can store three times the energy of gaseous hydrogen, which means that liquid hydrogen aircraft can fly longer distances than conventional aircraft. Liquid hydrogen has an extremely high energy and volume density, so the aircraft must have a significantly larger fuel tank.
The prototype has already been completed
A team of 44 students at TU Delft in the Netherlands has been working on a liquid hydrogen fuel cell aircraft for some time. They recently presented a 1/3 scale prototype, which is scheduled to make its first test flight in July.
The Phoenix is a redesigned version of the two-seat e-Genius electric glider developed at the University of Stuttgart. The e-Genius has covered 400 km with battery power, while the full-size Phoenix will fly up to 2,000 km on 10 kg of liquid hydrogen.
The prototype is not small, with a wingspan of 5.7 m and a weight of 50 kg. It will carry enough hydrogen for a flight of about 7 hours and a range of 500 km. The hydrogen is kept at a temperature of -253°C in the cooling tank, which, via a 1.5 kW fuel cell, charges the battery that powers the electric propeller on the tail of the aircraft. Sam Rutten, the prototype project manager, noted that although liquid hydrogen is inherently difficult to work with, they have moved from the design phase to the production phase, so the first steps to design the tank have been taken.
They are working on several projects
The full-size, two-seat Phoenix is also under construction and is scheduled to debut in July or September. It will have its first flight on gaseous hydrogen in the summer of 2022, with a liquid hydrogen flight planned for 2024. AeroDelft also plans to build a larger aircraft and a liquid hydrogen passenger plane, the Greenliner, capable of carrying 19 passengers and covering 952 km. Phoenix is a truly exciting project with huge potential. And the world needs ideas for liquid hydrogen like this if we are to eliminate the 2 per cent of greenhouse gas emissions that aviation produces.