Porsche say a hydrogen-powered passenger car could be viable.
The whole car industry seems to be a bit obsessed with battery electric vehicles as direct replacements to internal combustion engine powered vehicles in the coming decades. However battery power is not the only possible future. In fact, many major car companies are hedging their bets, splitting R&D between a few possible solutions, including synthetic fuels, hydrogen fuel cell vehicles, as well as internal combustion engines adapted to burn hydrogen as a fuel. Now, Porsche Engineering is exploring the possibility of the last of these three options.
When it comes to these ‘hydrogen engines’, specific output is typically quite low in real-world applications. Therefore, Porsche Engineering’s first concern was to match the power and torque of current high-performance petrol engines for their hydrogen engine. To do this, they started with a 4.4L V8 petrol engine in completely digital environment.
They digitally modified the engine model to have a higher compression ratio and a combustion system adapted to hydrogen as well as an all new turbocharging system. Turbochargers in hydrogen engines have to provide something like twice the volume of air mass versus those in petrol engines. On the other hand, the exhaust gas in hydrogen engines lacks the temperature required for sufficient propulsion.
To resolve this, Porsche Engineering explored using electrically assisted turbochargers. In some of the design studies, these turbocharging systems have additional control valves in the air system. Some even have electrically driven compressors. For the engine study, they finally settled on a turbocharging system with back-to-back compressors. This design has a coaxial arrangement of two compressor stages which are driven by the turbine or supporting electric motor using a common shaft. The process air flows through the first compressor, is cooled in an intercooler, and then recompressed in the second stage.
The result is a hydrogen-fueled V8 with around 590 horsepower (or 440kW), on par with the original petrol engine. Porsche Engineering (digitally) put it in an existing reference vehicle and found its weight was 2650kg. On a virtual lap of the Nürburgring Nordschleife, this imaginary test vehicle managed a very respectable time of 8 minutes and 20 seconds. That’s just a hair slower than the 2009 987 Porsche Boxster S. It had a top speed of 261km/h.
The best part is that no hydrocarbons, carbon monoxide, or particulates came out of the tailpipes at all. In fact, the only potential pollutant was nitrogen oxides, which Porsche Engineering managed to also cut down to well below upcoming Euro 7 standards. In fact, the amount of these nitrogen oxides emitted was close to zero throughout most of the engine map. Porsche Engineering’s digital optimisations enabled them to completely dispense of the exhaust aftertreatment system altogether and still be within future emissions regulations.
