Hydrogen in the tank

Hydrogen in the tank

automotive.at:Mr. Geringer, you are chairman of the Austrian Association for Motor Vehicle Technology ÖVK and organizer of the international Vienna Motor Symposium held annually in the Vienna Hofburg. What topics are on the program this spring?

Bernhard Geringer: One focus this year is climate-neutral drive, including fuel cells and hydrogen engines as well as, of course, pure electric drives and various hybrid solutions. The focus is also on energy sources for mobility and the automotive industry's path to autonomous vehicles. For this exciting discussion, we were able to win the Viennese high-tech company TTTech as a partner, which is at the forefront of the development of autonomous driving functions with its “The Autonomous” initiative.

The Austrian federal government wants to promote the production of climate-neutral hydrogen as part of its hydrogen strategy. So will we soon be refueling with hydrogen instead of petrol or diesel?

Some lectures at the engine symposium deal with the hydrogen engine, in which hydrogen is burned in a similar way to a natural gas or liquid gas engine. This is actually an interesting alternative to fossil fuels, especially if the hydrogen is produced using electricity from renewable sources. The engine developers have now succeeded in bringing the hydrogen engine to the same performance level as a gasoline engine through powerful charging. The great economic advantage of this drive solution is that existing combustion engines only need to be moderately adapted. The gearbox also remains the same, only the tank has to be replaced with a gas pressure tank.

BMW introduced a hydrogen combustion engine back in 2005 with the Hydrogen 7 model. Why didn't this prevail back then?

The BMW Hydrogen 7 only produced 260 hp and had a torque of 390 Nm. In comparison, a 760i with a petrol engine had an impressive 445 hp and 600 Nm of torque. But development has not stopped, and today's hydrogen combustion engines are even more efficient than gasoline engines, with an efficiency of up to 43 percent. In addition, the gas is now stored in pressure tanks for a long time without loss, whereas 18 years ago it was cooled down to minus 253 degrees Celsius and liquefied. Although the tanks were well insulated at the time, the hydrogen evaporated from them within a few days.

So is the technology already ready for series production today?

The hydrogen combustion engine will go into series production in 2024 and is definitely an interesting drive alternative for long-distance trucks and special vehicles. However, the lack of infrastructure prevents further spread in the passenger car sector. There are currently only five hydrogen filling stations in Austria that have to be supplied with the gas by truck - that is not ideal. There should be gas stations nationwide that are supplied via pipelines.

Isn't the use of hydrogen in a fuel cell significantly more efficient than in an internal combustion engine?

The fuel cell in combination with an electric motor actually has a higher efficiency in the part-load range, in which a car is primarily operated. In full-load operation, in which a truck mainly operates, the hydrogen combustion engine is in the lead. Another challenge in the operation of fuel cells is the high degree of purity of at least 99.97 percent that the hydrogen must have so that the fuel cell does not age prematurely. This technology also requires complex thermal management, as during operation it only dissipates waste heat via the cooling water and therefore requires twice the radiator surface area of ​​today's engines.

Are hydrogen engines actually completely climate neutral?

Only the so-called “green” hydrogen, which is produced with electricity from photovoltaics, wind or hydropower, is climate-neutral when used. If electricity from coal-fired power plants is used for production, this “brown” or “black” hydrogen is harmful to the climate and not sustainable. Climate-damaging CO2 is also produced when hydrogen is produced from natural gas using steam reforming or methane splitting, and radioactive waste is produced when produced using nuclear energy. As with any combustion process, the combustion of hydrogen in the engine also produces nitrogen oxides, which can be largely neutralized by a conventional SCR catalytic converter like in a diesel engine by adding AdBlue. In summary, it can be said that the hydrogen engine definitely has its advantages as a bridge technology - provided it is powered by green hydrogen.

Many Austrian suppliers to the automotive industry have specialized in components for internal combustion engines. Could the hydrogen combustion engine represent a future prospect for you?

In fact, several Austrian companies are already working on hydrogen technology. At AVL List in Graz, not only hydrogen trucks are being developed, but also a hydrogen racing engine. And Bosch is also working intensively on hydrogen solutions, from electrolysis to automotive applications. There are also economic opportunities for smaller suppliers, because numerous components are required for hydrogen propulsion, including tank systems, seals, sensors, shutdown devices, cooling systems, pumps, switching valves, etc.