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Grenchoice Forze (NL)

Greenchoice Forze is a hydrogen racing team, consisting of about 50 students of the Technical University of Delft. The team is multi-disciplinair; all the faculties are represented and the entire team is managed by students. Next to all technical tasks, also the promotion and management of the team is done by students. The management of the team consist of three fulltime members. Apart from the management, most of the team members are parttimers. These students are highly motivated and want to get some hands-on experience in their spare time. Other members are interns or graduates. All these students choose to be involved in this project because of its innovative, sustainable, educational and fun character.
greenchoice forze

Normally, a kart has a gasoline tank, a small combustion engine and an exhaust. The Forze II, however, is far more complicated. Instead of using a simple combustion engine that runs on gasoline, the Forze II has two DC electro motors (2) which are powered by a proton exchange membrane (PEM) fuel cell (3), supplied by Hydrogenics. The gasoline tank is replaced by a 5L tank (1) in which hydrogen is stored at a pressure of 200 bars. With a full tank, we can race for about 15 minutes.

Basically the Forze II works as follows: Hydrogen is fed to the fuel cell. In the fuel cell the hydrogen and oxygen react and produce electricity. The voltage produced by the fuel cell is then brought to a higher level by a DC/DC converter. The generated electric energy is then stored in boostcaps (4), which serve as an energy buffer between the fuel cell and the electro motors. When the driver kicks down the pedal, the engines subtract their energy from the boostcaps.

greenchoice forze

In more detail: Oxygen is subtracted from the air and the hydrogen is fed from the high pressure tank to the fuel cell. Therefore, the hydrogen pressure is reduced in 2 steps, by means of regulators and valves supplied by Swagelok. The first step is from 200 bars to 30 bars and the second step is from 30 bars to 5.5 bars. All hydrogen systems have been tested by Leak Control and can withstand a pressure of 1100 bars.

The 8 kW fuel cell consists of several devices, from which the most important one is the stack. In the stack, the hydrogen (H2) and oxygen (O2) are separated by a membrane. At the anode side, a catalyst splits the hydrogen molecules into protons and electrons (2H2 -> 4H+ + 4e-). The protons can go through the membrane to the oxygen at the cathode side, but the electrons cannot and have to go through an external circuit, forming a complete circuit. The reaction on the cathode side is then as follows: 4H+ + 4e- + O2 -> 2H2O. As you can see, pure water is the only exhaust coming from the fuel cell!

For the energy storage system, 32 Maxwell Boostcaps are used. A boostcap is an ultra capacitor, a sort of battery which can store and release energy really fast. The capacity of one boostcap is 3000 Farad, which is incredibly high compared to capacitors used in electronics (in the order of microFarads). Not only energy generated by the fuel cell, but also energy recovered by regenerative braking, will be stored in these boostcaps. When the boostcaps are fully charged, the Forze II has a maximum power of 28 kW (38 HP).

The voltage produced by the fuel cell is not high enough to charge the boostcaps, so a DC/DC converter is implemented in the kart. It converts the voltage coming from the fuel cell to the desired voltage for the ultra capacitors. Another important property of the DC/DC converter is that it works as a diode. The DC/DC converter makes it impossible to have a current flowing back into the fuel cell. The DC/DC converter is developed in cooperation with ECN.

The two motors used are Perm 132 DC electro motors. These motors are not connected directly to the boostcaps, because a throttle is needed. Each motor is controlled by a separate motor controller. This way an electronic differential is possible. Currently, we are developing a motor controller which can control both motors, but is half the weight and just a third of the size of the two off-the-shelf controllers. This controller will also have a lot more features, like for instance a reverse mode.

All the electronic parts are controlled by two printed circuit boards (PCB’s), which Greenchoice Forze developed in cooperation with Betronic. The PCB’s were produced by Cyner. Most of the micro controllers placed on these PCB’s are supplied by NXP.

Of course, all this technology has to be protected by bodywork. The bodywork is made of a special composite, which is by far not as polluting as other composites. A natural fiber, flax, is used for bodywork of the Forze II in combination with a bio-based resin. This bio-based resin is developed by DSM. The whole bodywork is 70% renewable. The Forze II is the first application of this composite and in that way, it served as a testing platform for DSM. After it was finished, the whole bodywork was painted by Van den Berg Autoschade with Glasurit products.

The Forze II is, from a mechanically point of view, constructed as a race kart. The most significant feature of such a vehicle is the lack of a suspension. All damping has to be done by the chassis (5) itself, which demands special care during design and construction. The chassis of the Greenchoice Forze kart, the Forze II, has been developed in cooperation with Kombikart Racing Parts B.V.

fz greenchoice forze


0TH place Solvay Umicore Zero Emission Racing Team, 3 points
1st place UnizartecH2, 18 points
2nd place Imperial Racing Green ,37 points
3rd place Greenchoice Forze, 38 points