I had several ideas for this project, a few of which would be far too difficult to accomplish. Originally, I was thinking of creating a regenerative braking system. Regenerative braking is essentially a way to regain electricity the rotation of the wheel. For instance, most of the major car companies have this system in place. This works by gaining energy by reversing the motor into a generator.
This design was particularly difficult because I did not have the resources to automatically switch to circuit between charging mode and driving mode (school did not have the switch to do that). My second design was to create an AC generator (which is used in the industrial level to power major civilian centers) with a AC to DC converter to charge a battery. The AC generator is particularly interesting as it is the only type of generator use in industrial scale energy production.
The turbine to turn turn the generator was designed as a Tesla turbine, which functions as a bladeless turbine utilizing the boundary-layer effect to rotate (with a maximum efficiency of ≈95%). This is preferable to other methods of turning the rotor as the tesla turbine has a far higher efficiency and does not depend on steam or other similar sources which may be environmentally damaging. The design for this project would be annoying as it would have to rely greatly on 3D printing to create the appropriate shapes.
The third design was an ion drive. Ion engines use ionization to create a flow of air or fuel (or in rocketry, ions/elections themselves) in order to generate energy. The dangers of making one is immense, and is likely to cause death if a shock is to occur (I was originally expecting around 8-10kV for the Ion drive to create the desired thrust). It is evident in this fact that it is too dangerous to build, albeit very eco-friendly. I will not include a video as I do not indorse the construction of such devices outside of a safe environment.
My final design was the most ridiculous, which was to create a simple turbojet. I quickly removed this from the possibilities due to the dangers of handling jet fuel and of the combustion of air needed for regular function of the jet engine. I will not include a video for this as no explanation is needed for why I did not choose this.