Abstract
Since the 1980s, climate change has become an increasingly pressing topic in politics and everyday life. The world’s transition to cleaner, more renewable energy sources has been painfully slow over the years, which has consequently caused the global temperature to rise exponentially. Wind is a commonly talked-about solution to this climate crisis. Some of the main drawbacks in transitioning to wind energy are cost and land use. A single wind farm requires about 80 acres of land, and a single turbine can cost about $3 million. Our group wanted to address these issues in our design project. Our goal was to build a small, inexpensive source of wind energy that can be scaled up for widespread use. We discovered that vibration sensors generate voltage when mechanical strain is applied to it. We wanted to maximize the flutter of the vibration sensor to maximize voltage output, and see if that voltage could be stored in a battery.
Problem Statement
The current use of nonrenewable energy is both inefficient and dangerous in the long term. Our goal is to find a way to convert passive sources of energy into electricity that can be stored and reused for everyday applications. This solution will lower the incentive to use nonrenewable energy resources, while making renewable energy more cost-effective and less harmful to the environment.
Design Alternatives
These are some of the ideas we came up during our brainstorming:
1. Piezo vibration sensors convert wind energy into electricity
2. Hand crank that converts rotational motion into electricity
3. Wheels that spin as force is applied to it from a car that converts rotational energy into electricity
4. Piezoelectric platforms that generate electricity when pressure is applied on it
A mind map with our ideas to establish relationships between them (above).
After narrowing our ideas down, we decided to utilize piezo vibration sensor technology to collect wind energy and store it in the form of electricity.
Design Evolution: Optimizing the Vibration Sensor
Piezo vibration sensors works on the principle of piezoelectricity, which induces a potential difference, i.e., voltage in response to a mechanical stress, which makes them an alternative to the traditional way of electrical energy generation.
First, we experimented with different sensor sizes and shapes by creating low-fidelity prototypes made out of thin plastic material and toothpicks (shown in the picture to the left below). A height about 1.4 inches was estimated to generate the most voltage since it had significant amplitude of vibration and maintained high frequency of vibration.
Then, we tested out different sensor attachments made out of TPU to determine the structure that could cause the highest deflection, which could increase strain that generates a voltage. The most successful attachment is shown to the very right above.
The most optimal mass for the sensor was also experimented for. Results showed that the most advantageous mass to increase voltage depended on the sensor geometry and where exactly the mass was placed on the sensor.
Based on our inverted triangle geometry, the best position for additional weights were right below the two upper vertices of the shape. One gram weights were placed on both sides.
Design Evolution: Wind Tunnel
We used a wind tunnel to simulate wind movement outside. The fan pulls in air from the left side. We were able to place the sensors in the wind tunnel and adjust the airflow speed. We used pitot static tubes (below, left), which use pressure differences, to calculate wind speed. The wind tunnel we had was able to simulate light to moderate breezes on the Beaufort scale.
Additionally, we tested different ways to mount the sensor (below, right). We tested orientations and flexibilities of materials. We concluded that more flexible materials and a slightly angled orientation produced the most vibrations
Design Evolution: Storage and Usage
The voltage from the vibration sensor alone is unable to charge a battery because it produces alternating current, or AC, when batteries charge using direct current, or DC. I built a full bridge rectifier to convert the vibration sensor’s AC into DC.
This is the AC voltage output. This is unable to charge a battery.
This is the rectified DC voltage output without a capacitor to smooth the signal.
This is the desired full sine wave signal.
Final Design and Testing Results
The design bears resemblance to a tree in order to be less obtrusive to the environment. Each leaf is a vibration sensor that generates electricity as wind applies mechanical stress and strain to it.
Below are our testing results:
We used the upside-down triangle design for the vibration sensor. We set the vibration sensor to an amplitude of 2.5 millimeters and a frequency of 10 Hertz. It was able to charge the pair of 3.7 lithium ion batteries by about 0.054 volts in 20 minutes. The signal seen on nScope was the signal produced by the vibration sensor.
With the collective efforts of many sensors, multiple batteries can be charged to store electricity that can be used in many different ways, such as outdoor lights and power banks pedestrians can use to charge their devices.
Project Video
Conclusion
Our team was successfully able to generate electricity using a vibration sensor and power a battery. We also came up with optimal sensor geometry to maximize the device’s voltage output. However, a single vibration sensor was unable to produce a significant amount of electricity. It would take an entire day for the vibration sensor to power a single 3.7 volt battery at optimal wind conditions. Our next step on this project would be to optimize the device’s charging speed as much as possible.
Some additional future steps are to continue to experiment and improve the sensor geometry. Here we have some preliminary tests on attaching a large, thin pieces of masking tape. We would also like to create a mount for the sensors that allow the angle to be adjusted in real time based on local weather conditions.
References and Works Cited
2022, Lucas PodmoreFeb 24. “What Materials Are Used to Make Wind Turbines?” AZoM.com, 24 Feb. 2022, https://www.azom.com/article.aspx?ArticleID=21371.
Bad Request, https://www.christies.com/features/Studio-Visit-Jonathan-Prince-10077-3.aspx%20%E2%80%8B.
Cascone, Sarah. “New York’s 15 Best Summer Public Art Installations.” Artnet News, 28 Mar. 2019, https://news.artnet.com/art-world/new-yorks-15-cant-miss-summer-public-art-installations-315396.
“Fossil Fuel.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., https://www.britannica.com/science/fossil-fuel.
Jensen, Allison. “Examining the Pros and Cons of Hydropower.” Manufacturing.net, 22 July 2021, https://www.manufacturing.net/chemical-processing/article/13245967/examining-the-pros-and-cons-of-hydropower%20%E2%80%8B.
Last Minute Engineers. “The Full-Wave Bridge Rectifier.” Last Minute Engineers, Last Minute Engineers, 15 May 2022, https://lastminuteengineers.com/the-full-wave-bridge-rectifier/.
“LDTM-028K Measurement Specialties: Mouser.” Mouser Electronics, https://www.mouser.com/ProductDetail/Measurement-Specialties/LDTM-028K?qs=Pz4gaf3%252B8zwC7TEQph04jQ%3D%3D.
“News & Features.” News & Features | NOAA Climate.gov, https://www.climate.gov/news-features.
“Piezo Vibration Sensor – Large.” SEN-09196 – SparkFun Electronics, https://www.sparkfun.com/products/9196.
“TE Connectivity Vibration Sensor 0°C → +85°C, Dimensions 25 (Mm) x 13 (MM) x 205 (ΜM): Te Connectivity.” RS Components India, https://in.rsdelivers.com/product/te-connectivity/1002794/te-connectivity-vibration-sensor-0c-85c-dimensions/8937086P.
Team, Energiewende, et al. “Europe Must Choose a Green Future.” Energy Transition, 14 May 2018, https://energytransition.org/2018/04/europe-must-choose-a-green-future/.
“Wind Energy.” National Geographic Society, https://www.nationalgeographic.org/encyclopedia/wind-energy/.
Pefhany, S. “4-Terminal Tactile Switches.” Electrical Engineering Stack Exchange, 21 Feb. 2014, electronics.stackexchange.com/questions/100540/why-do-some-tactile-switches-have-4-terminals/100556#100556. Accessed 19 July 2022.
Meet the Team
Kwasi Buansi
Alice Chen
Stephen Chen
Anna Zhong
