Global warming has a significant long-term negative effect on the environment and earth’s atmosphere due to the CO2 emissions from various human-developed sources. Global warming is an overarching problem humanity must overcome and it begins with finding alternatives for transportation and power generation rather than utilizing fossil fuels.
In 1999, AIChE (American Institute of Chemical Engineers) introduced efforts towards producing technologies and processes that are more environmentally friendly by starting an annual student chemical engineering competition, the AIChE Chem-E-Car Competition. This competition revolves around building a small-scale (shoebox-size) car that is powered by energy produced by a chemical reaction. A chemical reaction must also be used to stop the vehicle after it has traveled a specified distance. Students compete with teams from other universities in guiding their car to a certain distance while carrying a load with a specified weight. The distance the car must travel and the weight it must carry are not revealed until the day of the competition. Operation of the car is controlled by varying the concentrations and volumes of the reactants.
The car must be capable of driving 15-30 meters in less than two minutes while carrying a load of up to 500 mL of water.
To achieve this goal, we utilized 12 thermal electric generators (TEGs), which use a temperature differential to generate the current and voltage to power the car. To create this temperature differential, an acid base reaction of NaOH and HCl generates heat in a “hot reactor,” while a “cold reactor” is filled with an isopropyl alcohol dry ice bath. The TEGs are sandwiched between the reactors and wired to produce the necessary current and voltage requirements.
For the stopping mechanism, we used an iodine clock reaction, using hydrogen peroxide, potassium iodine, hydrochloric acid, sodium thiosulfate, and starch. The reaction has two steps: the first step generates iodine molecules, and the second step consumes the iodine very quickly. After the second step reaches completion, the iodine molecules are free to form a complex with the starch; this turns the solution a very dark blue/black color. The time before color change can be altered by varying the amount of thiosulfate. The color change is monitored by a photosensor which relays the information to an onboard Arduino control board which triggers the car to stop after the solution turns dark. The time of the iodine clock reaction is calculated based on the specified weight and distance the car must travel. We use an equation to predict the required volume of thiosulfate to the time it takes to reach the specified distance based on the speed the car travels with various loads.
Front row: Warrick Smart, ChE, Allison Fox, ChE, Alfredo Cepero, ChE, Tyla Seelye, ChE, John Jennings, ChE. Back row: Carlos Ray, ChE, Victoria Horton, ChE, Aubrey Malowany, ChE, Sandra Faragalla, BME, Antionne Byrd, BME
Robert Wandell, Ph.D.