As you know, our racing cars run on hydrogen. This hydrogen is used during the race or in track testing. So, before driving we need to refuel our car by filling it up with hydrogen. But how does this refuelling work? How is it different from refuelling a petrol car and what developments will be there in the future?

How do you refuel a hydrogen racing car?

Refuelling our cars is a bit different than usual with regular petrol cars or electric vehicles. It requires special refuelling stations that can deliver hydrogen into the tanks at high pressure. Of course, we can’t just drive a racing car across the public roads to visit a station. However, filling up our racing car is actually not that different from a normal hydrogen-powered road car. The refuelling stations for hydrogen are a bit different from your average gasoline pump. They are capable of filling up our tanks at a very high pressure, while also cooling the hydrogen that goes in. At the time of writing, there are 10 hydrogen refuelling stations in the Netherlands. When we arrive at one of these stations, we open the curtains of the trailer and do some final checks. If everything is okay it is just a matter of connecting the car to the pump as any other hydrogen vehicle would. After a while the hydrogen tanks are full, we decouple the part that connects the car to the pump, also called the ‘receptacle’, close the trailer and we are ready to race!

What happens during refuelling?

Once the car and the refuelling station are connected, hydrogen will start flowing into the tanks of the car. The tanks in our cars have a normal working pressure of 700 bar, thus the hydrogen needs to be compressed quite a bit for the tank to get full (as an empty tank will be about 20 bar). This compression causes the tanks to heat up a lot. Because our tanks are made of composites we can’t let them get past 80 degrees Celsius. To make sure the tanks do not overheat the hydrogen is pre-cooled to -40 degrees Celsius before it enters the tank. During refuelling, however, the temperatures rise quite a bit above ambient, so to make sure we have a full 700 bar at ambient temperature the refuelling station actually puts 875 bar in the tanks! After the hydrogen in the tanks has cooled, the pressure will get back to the nominal 700 bar.

To ensure this process is safe and controlled the car and the refuelling station communicate with each other. The car sends the pressure in the tanks and the temperature of the tanks to the refuelling station so that it can monitor these parameters at all times. To make sure this communication goes smoothly we need to be able to connect the receptacle in the car to the one from the pump in a proper way. For this we use the receptacle supplied by WEH, ensuring us a good connection with the refuelling station for safe and efficient operation.

What future developments are we investigating?

Currently, we refuel at normal hydrogen refuelling stations scattered throughout the Netherlands, however, these can be quite far from the tracks that we want to race or test on in the future. Because of this, we lose a lot of time between sessions on refuelling the car. In the future, we will need mobile refuelling options that we can take with us when we go to the race track. This allows us to quickly refuel between practice sessions and thus gives us more time on track. When we start participating in races that take longer than one hour we will need to refuel during the race. For this, it is essential to have a refuelling solution on the track that will quickly fill up our tanks. However, using the current hydrogen storage system in the car we can only race competitively for one hour. Refuelling hydrogen gas after this using a mobile station at the track is a serious, short-term option for us.

An interesting thing to look at for us in the future is the implementation of liquid hydrogen. In case we can bring more energy with us, we can race longer without going for pitstops. This is crucial during endurance racing where races last more than four hours with some, such as the famous 24 hours of Le Mans, even reaching the 24-hour mark. The only way to bring more hydrogen with us, is by storing (and refuelling it) in a liquid form. This way the hydrogen is much more energy-dense in volume and thus we can bring more hydrogen in our car. In the future of Forze, this will be the next step to take hydrogen racing to an even higher level.

In conclusion

So now we know that refuelling a hydrogen racing car is almost identical to filling up a normal hydrogen-powered vehicle. The procedure itself is quite different from refuelling a petrol, or charging an electric car, since the refuelling station and the car communicate with each other to make the high-pressure refuelling go smoothly. Finally, we are investigating a slew of future possibilities so we can stay competitive in every class we race in. Don’t be surprised next time you are at a hydrogen refuelling station and you see us filling up one of our cars in the trailer!

Tech Talk: Refuelling

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