The Lorax
UC San Diego's second car competed at the 2013 AIChE Western Regional Conference hosted here at UCSD. Our team placed 8th in the car competition and 3rd in the poster competition.
Propulsion Mechanism: Thermoelectricity
The propulsion mechanism is composed of 12 thermal generators with a combined output of 12 volts and 1 ampere. These thermal electric generators take advantage of the Seebeck effect to convert differences in temperature into usable electricity to power the car. The temperature gradient is produced by placing rows of thermal electric generators in contact with boiling water on one side and in contact with an ethanol-dry ice cooling bath on the other.
Stopping Mechanism: Foaming Reaction
The car is controlled by the transmittance of light to a photo resistor. In the absence of light, the resistance of the circuit increases to a point where all power dissipates, causing a break in the circuit. The foam used to block light to the photo-resistor is produced by the catalytic decomposition of hydrogen peroxide in the presence of yeast by the following reaction:
2H2O2 (aq) → 2H2O (l) + O2 (g)
This decomposition reaction produces bubbles in solutions with sufficient surface tension preventing light from hitting the photo resistor.