STEM I is taught by Dr. Crowthers and is a research-based class where students conduct a long-term independent research project in a field of their choice. In class, we practice reading and understanding technical scientific literature, and present in various settings, from school-wide elevator pitches to small group projects. Each term, we have regular update meetings to present findings from existing scientific research and our own projects, which culminate in school-wide science fairs in December and February.
As global energy consumption and demand continues to rise, there is a clear need for sustainable energy storage solutions. Current energy storage methods are predominantly done in the form of batteries, most of which involve heavy-metal-based designs. However, the mining processes necessary to source the materials in these designs make them extremely environmentally harmful and a net-negative to sustainability efforts. My STEM project aims to engineer a novel battery, capable of undergoing the same electrochemical processes present in current batteries, but using bioderived compounds in the design instead.
Lithium-ion batteries are the main form of global energy storage, but cause water pollution and accelerating climate change during mining.
The engineering goal of this project is to engineer a low-cost enzymatic fuel cell (EFC) that can produce sustainable electricity.
With global electricity demand projected to steadily increase for the foreseeable future, dependence on lithium-ion batteries, or LIBs, as primary energy storage technologies continues to rise. However, the manufacturing processes needed to mass-produce these models pose several environmental concerns, ranging from excessive water usage to habitat destruction. Therefore, there is a need for an economically and environmentally sustainable alternative. Fuel cells are one such alternative and involve systems built almost entirely from bioderived compounds, leading to minimal environmental impact. Additionally, fuel cell designs are highly adaptable for cost-sensitive use cases. This project explores the potential of a novel enzymatic fuel cell, or EFC, utilizing maltodextrin, sorbitol, and galacturonic acid as fuel sources, catalyzed by α-amylase. The system also features the use of tannic acid as a novel electron mediator. Both novel fuel sources showed higher mean voltage and mean current density compared to the control (p < 0.01). Analysis of mean current density showed a highly statistically significant difference between enzyme treated galacturonic acid compared to the other groups (p < 0.001). Furthermore, there was statistically significant correlation between enzyme mediation and higher current density (p < 0.01). These results display the potential for EFCs treated with novel fuel sources to be sustainable and efficient alternatives to LIBs without nearly the same environmental concern. As the world grows more digital, EFCs could be the preferred next-generation power-source for non-energy-intensive tasks.
If you're having trouble viewing the file in your browser, use this link: STEM I Graphical Abstract.
In the early stages of my project, I developed an infographic to summarize my work up until December Fair, which served as a methodology graphic, but also useful background information for my project. In this graphic, I've described the methods I used for creating the Python simulation code that resulted in my preliminary data. Furthermore, I outlined the potential benefits of my model, such as high short-term energy output, helping to address the engineering need.
Find my project documents here: Documents.
The chosen testing methodology involved the use of petri dishes with agar, into which the chosen configuration of fuel source, enzyme, and electron mediator were added. The testing of the cells themselves involved assembling the circuit and using the multimeter, resistor, and alligator clips to get data readings. To assemble the circuit, graphite rods were taped together, with two at each electrode, and bound to a singular copper wire for each end of the cell. The wires were then connected to a 5.6k-Ω resistor to measure voltage and current under controlled resistance. The readings for the circuit were taken from a multimeter with its probes connected to the point at which the copper wires connected with the resistor. Data readings were collected at the following points: one, five, ten, fifteen, and twenty minutes after the incorporation of the fuel.
If you're having trouble viewing the file in your browser, use this link: Methodology Graphic.
Figure 1 shows the results of Tukey’s HSD analysis of differences in mean current density as shown from a One-Way ANOVA.
Figure 2 shows the linear relationship between voltage and current and the parabolic relationship between power and current density.
Figure 3 shows the results of Student’s t-test for analysis of the effect on enzymes on mean current density grouped by fuel source.
Figure 4 shows the linear relationship between voltage and current using Ohm's Law as a theoretical model.
Figure 5 shows the parabolic relationship between power and current density.
Figure 6 shows the results of polynomial regression methods used to create power density curves for each group.
Analysis of the data collected shows a variety of positives. Firstly, measured differences in current density and mean voltage were shown to be highly statistically significant through the use of Student's t-test and a One-Way ANOVA supplemented with a post-hoc Tukey's HSD test (p < 0.01). Additionally, one-tailed p-values measured for differences in the average of these metrics for groups with the same fuel source showed significance (p = 0.02). This shows the effect to which a novel enzyme-electron mediator system can efficiently produce sustainable energy. Furthermore, it paves the way for future EFC research to experiment with underresearched fuel sources, such as sorbitol and galacturonic acid, by describing a framework and system-level design for constructing these cells at low costs. This contributes to the significance of the project by showing the extent to which slight modifications to existing EFC designs can drastically lower cost, while delivering relatively similar results and output. Therefore, the engineering objectives are deemed to be attained and the engineering need has been addressed.
Overall, the project attained the engineering objectives assigned for performance, cost, usability, and safety. Using a novel design that bridges past scientific literature with findings from real-world testing, the model displayed high potential for use in specialized lab environments with even higher material standards and lower financial restrictions. In environments where cost is key, the model proved to be extremely effective in its capability to generate high amounts of energy per unit of fuel and per unit-area. Applications of the cell include small-scale, non-energy-intensive tasks such as powering an LED or small electronic devices. Therefore, the model is capable of providing tangible solutions to rising concerns over material sustainability and scarcity surrounding modern-day lithium-ion batteries.
In my references file, you can find existing scientific literature related to my project that I used for competitor analysis, design inspiration, and general knowledge in the field.
A Quad Chart is a way to summarize different parts of a research project, like the background, methodology, results, and next steps. Here, you'll find a Quad Chart that I made prior to December Fair outlining the status of my work to that point.
If you're having trouble viewing the file in your browser, use this link: Quad Chart.