Despite heavily investing in synthetic fuel, the sports car maker won't overlook other options.
Porsche recently conducted a completely digital study of the potential of hydrogen combustion engines, focusing on how effective they would be at conquering the Nurburgring.
Now, it's important to note that we're not talking about fuel cell vehicles like the Toyota Mirai and Hyundai Nexo. These vehicles use hydrogen as part of a chemical reaction, which creates electricity and powers an EV motor. A hydrogen combustion engine sticks to the same principles as internal combustion. Instead of using gas or diesel for the combustion process, a hydrogen combustion engine uses a mix of oxygen and, erm, hydrogen.
Porsche looked at the available hydrogen ICE engines and found that they're mostly used in commercial vehicles and have a relatively low specific output. "For the passenger car sector, this is insufficient," says Vincenzo Bevilacqua, Senior Expert Engine Simulation at Porsche Engineering.
"We have therefore developed a hydrogen combustion engine that aims to match the power and torque of current high-performance gasoline engines as a concept study," said Bevilacqua.
Porsche chose its existing twin-turbo 4.4-liter V8 gasoline engine. It's not an engine from Porsche's current range, as all V8 models like the Cayenne and Panamera rely on a 4.0-liter twin-turbo V8 engine. Instead, this engine is a digital data set, to which Porsche could easily make modifications needed for the hydrogen combustion cycle. The digital 4.4 V8 runs a higher compression ratio and a combustion cycle adapted to hydrogen, but the biggest problem was turbocharging.
"For clean combustion of hydrogen, the turbochargers have to, on the one hand, provide around twice as much air mass as they do in gasoline engines. On the other hand, however, the lower exhaust gas temperatures result in a lack of energy for their propulsion on the exhaust side," explains Bevilacqua.
It was clear a conventional turbocharger setup was out of the question, so Porsche's engineers came up with four possible solutions, incorporating ideas borrowed from motorsport. CarBuzz may have accidentally stumbled upon one of these options a while back.
All of the solutions consisted of electrically assisted turbochargers combined with additional control valves in the air system or electrically driven compressors. Electrically assisted turbochargers are not new, but they're only now starting to filter through into production cars like the Mercedes-AMG C43.
"For the engine study concerned, the development team selected a turbocharging system with back-to-back compressors. The special feature of this design is the coaxial arrangement of two compressor stages, which are driven by the turbine or the supporting electric motor using a common shaft. The process air flows through the first compressor, is cooled in the intercooler, and then recompressed in the second stage," explains Bevilacqua.
Porsche arrived at a power output of 590 horsepower, which it says is on par with the original gas unit. We suspect Porsche refers to the 4.0-liter twin-turbo used in the Panamera Turbo S, as it produces 620 hp. The additional 400cc likely comes from finding the sweet spot for the hydrogen combustion process.
Further evidence is provided by the model Porsche chose to test the performance. It mentions a luxury segment vehicle with a relatively high weight, which sounds exactly like a Panamera.
The vehicle ran a lap of the Nurburgring using a computer-based representation and completed a lap in eight minutes and 20 seconds. It did so without releasing hydrocarbons, carbon monoxide, or particles. It still released nitrogen oxides, so Porsche recalibrated the engine's operating strategy for the cleanest possible combustion.
"As it turned out, the nitrogen oxide emissions are well below the limits set by the Euro 7 standard currently under discussion and are close to zero over the entire engine map," said Matthias Boger, Specialist Engineer Engine Simulation at Porsche Engineering.
The above statement needs context to be fully grasped. The Air Quality Index is widely recognized as a benchmark for assessing air pollution. The air quality is classified as good if there are 40 micrograms of nitrogen oxide per cubic meter. "The hydrogen engine's emissions are below this limit. Operating it, therefore, has no significant impact on the environment," says Boger.
Porsche says this hydrogen engine is unlikely to enter production in its current form, but that was never the project's goal. "The study allowed us to gain valuable insights with regard to the development of high-performance hydrogen engines and add models and methods specifically for hydrogen to our virtual simulation methodology," explains Bevilacqua. "With this know-how, we are ready to efficiently handle future customer projects."