The use of fuel cells for the primary drive propulsion system for aircraft of general aviation offers significant benefits, which could not be gained with conventional piston engines. This applies especially to operational and maintenance costs, security and comfort for pilot and passengers. And in some specific disciplines like range it is also predominant to battery powered aircraft.
Increase in Security
Every year, more than 70 % of technical defects, accidents and serious interferences in the operation of aircraft in general aviation fall upon the drive-train and are next to human error the largest single item in the accident statistics in Germany for aircraft with a maximum take-off weight under two tons.
fig 1: accident statistics in general aviation (source: Bundesstelle für Flugunfalluntersuchung: Jahresbericht 2004, 2005, 2006)Electric drives allow new security and redundancy concepts to reduce the failure probability of the powertrain. Full electric hybrids tolerate the total loss of one energy source since the modular structure prevents a total performance failure. Back-up power sources can be integrated in electric propulsion systems to provide short term energy for a safe landing.
Decrease in Costs
In general aviation, the operating and maintenance costs are much more important than the purchase price. Due to the high approval requirements of the air authorities the development of aircraft engine lags decades behind modern vehicle engines. So a fuel consumption of about 50 litres per hour of avgas for a 4-seater aircraft is more rule than exception.
Due to the higher energy content of hydrogen, the higher efficiency of electrical propulsion systems and the separation of power and propulsion generation fuel costs can today be reduced by 50 to 100 percent. The current price for one kilogram hydrogen is about 8 €. Related to the diesel equivalent the price is about 2,4 € per liter. With respect to the higher system efficiency we gain a price of about 1,2 € per liter. In comparison the current price for avgas is 2,25 € per liter. By an usual fuel consumption of 50 liters per hour and an annual utilization of 400 flying hours this leads to a saving of 21000 € per year only due to the fuel costs.fig 2: fuel consumption and fuel costs for 2-seated aircraft (source: Peter Bachmann: Ein- und zweimotorige Flugzeuge: Bilder, Daten, Kosten)
For conventional aircraft maintenance costs are the main cost driver. Typically, there are small checks every 50 flying hours, with the change of motor-oil, sparking plug and other consumables. Additionally, every 100, 200, 400 flying hours as well as annually the aircraft is completely grounded for several days because of detailed inspections of motor and other highly loaded parts. Fuel cell and battery systems require fewer consumables and can be monitored electronically. This results in lower maintenance effort and longer inspection cycles and therefore in further economies especially for flight schools or charter carriers with a high utilization.
Environmental Compatibility
The CO2 emissions per passenger kilometre of small aircraft are the largest compared to all other vehicles. When using hydrogen in combination with a fuel cell no direct CO2 and NOX are emitted. Only water vapour will be ejected but not in hights where it could harm the climate. The extremly low noise of the powertrain additionally leads to fewer limitations in airfields and lower landing fees and more relaxed airfield residents.
Aviation: Pioneer in Hydrogen Infrastructure
Providing international and larger regional airports with hydrogen stations allows an area-wide aircraft operation at relatively little investment compared to the required infrastructure for fuel cell powered automotives. Furthermore, apron vehicles in isolated operation guarantee their continuous utilisation.
So the general aviation represents an early market for fuel cell and hydrogen infrastructure and contributes to their growing importance.

Long ago in autumn 2005, when Len was lank and my hair was full (okay it was less thin), I sat in one of the many cafeterias at our university as Len came by and asked if I had a little time. Distracted by my coffee and the nice view (the cafeteria was nearly the only place to see some women) I said yes. If I had guessed then…I would probably had said yes, too. So he explained to me that he had found a competition. This was the Berblinger Competition, with the objectives of the preliminary design of a two-seated aircraft which should be outstanding in environmental friendliness, safety, construction and economics. He had already talked to our Professor Rudolf Voit-Nitschmann, who has been formally winner of this competition in 1996 with the solar powered aircraft icaré 2. He was very pleased about that idea so he supported Len to take part in this competition. So Len and Prof. Voit-Nitschmann made some brainstorming and came to the conclusion that the best idea would be a fuel cell powered aircraft with a very aerodynamic design causing less drag and therefore low energy consumption. Additionally will this drive train emit no exhaust fumes except for water vapour and very little noise. This was the moment when I got involved. He asked me if I liked to participate in this competition and do the work for the drive train. Well, I was at that time on the lookout for a diploma thesis so why not?! After we elaborated the preliminary design under the name Hydrogenius and sent it to the city of Ulm, organizer of the Berblinger Competition, we finalized our diploma thesis and waited for the result.


Autumn 2006: Victory at the Berblinger Competition

We won the Berblinger Competition. Now we had a preliminary design of an aircraft comparable to conventional aircraft in performance and range and which is environmental friendly and economic if you desist from the purchase price. In addition we had some price-money from the competition. With the money we celebrated our victory and invited lots of people from science and industry. One of these visitors was Artur Fischer, founder of the Fischerwerke, honour senator of the Universität Stuttgart. He was so convinced by the project Hydrogenius that he donated us the first 100.000 €. Well, we choked up and clearly moved decided to realize the Project Hydrogenius.

Spring 2007: Artur Fischer and the model of our HydrogeniusEditorial Note: Club of Pioneers stands for the support of upcoming pioneers in the field of sustainable mobility. Since we are already covering the development of the Ventomobil, we are proud to present another promising project coming from exactly the same University in Stuttgart. It's about the amazing idea to fly with Hydrogen: The Hydrogenius project! Enjoy the first guestblog written by Steffen who founded with Len the Hydrogenius Team... and stay tuned, the guys will keep you updated!