The need for energy is increasing with the aim of becoming more powerful in the world for countries.Mechanical energy harvesting is a potential strategy that can be used to develop self-powered sensor systems and offer a solution to the battery problem.
By using the piezoelectric and magnetic effect in a hybrid way, it is aimed to make a digital agriculture module that can harvest energy from the vibrations of the trees and measure agricultural data.The system to be produced is intended to be non-linear, simple, highly efficient and low-cost.
In the system, we used two magnets, four coils, piezoelectric material, metal cantilever beam, measurement module, and a plastic structure.The working principle of the system developed is based on the energy production of induction by the motion of the magnets between the coils and by the flexible piezoelectric element attached to the cantilever beam.The optimization of the system has been studied and the optimum number of turns in a coil, coil length, cantilever beam length, and tip mass have been determined.The power of our system is 60.9mW at 1Hz ambient vibration.The estimated cost of our prototype is 192.19TL/$36,24/€31,83.
The innovation in the system is the coupling of different electromagnetic and piezoelectric systems and designing a new system that can be used for wireless sensor network applications.In addition, with the gear system that we used, energy can be harvested regardless of the direction of vibration.It should not be forgotten that this system may have many uses even outside agriculture.Vibrations are everywhere.
As it can be seen in our modern world, each and every sector is changing dynamically. Meaning not only the fact that each one of them will serve for the good of mankind but also will require an aspect from it. This aspect may differ from sector to sector according to its needs. But if we take a look at the general topic from a wide angle, we would see that they all have one conundrum in common: Energy.
One of the results of the 4th Industrial Revolution, digital agriculture has started to grow gradually with respect to the technological developments, such as the Internet of Things. These systems are used in “Automatic Crop Irrigation”, “Precision Agriculture”, “Pest Control” and “Food Production and Safety”. Consequently, digital agriculture will play a key role in the future of food production and solve the starvation problem. While having such benefits, this area requires measurement modules which work with self-sustaining mechanisms. Meaning it is no different than other sectors: it has the energy issue.
While brainstorming about this topic in awe, I happened to ask myself an intriguing question: "Can tree vibrations be a viable energy source for agricultural applications?" Man has always tried outer parameters as solutions for such subjects but never really thought about the inner features of systems. Trees have always been around us, swinging in the winds... Why not use their mechanical energy for the good of systems attached to them?
1. Challa et al., in the article which was written in 2009: piezoelectric and electromagnetic energy harvesting techniques were investigated. The resonance frequency of the first system is 21.6 Hz. A maximum power of ~ 332 μW was produced by the hybrid system, resulting in a 30% power increase compared to the 257 and 244 μW powers obtained from the optimized single piezoelectric and electromagnetic energy harvesters, respectively.
2. Kwon et al., in the article which was written in 2017: a frequency up-conversion energy harvester using two cantilever beams was developed. Piezoelectric and electromagnetic mechanisms were used together to increase energy production. A system with a maximum power output of 5.76 mW, which is capable of converting the extremely low-frequency mechanical oscillations into electrical energy efficiently by means of frequency amplification with the layered structure (substrate and two cantilever beams) was developed.
3. Beeby et al., in the article which was written in 2007: a small (component volume 0.1 cm3, practical volume 0.15 cm3) electromagnetic harvester optimized for low ambient vibration level based upon real application data was presented. The generator uses four magnets arranged on the cantilever beam and a wound coil located within the moving magnetic field. Properties of the coil and magnet size were optimized. The final device produced has a resonance frequency of 52 Hz, 0.59 m/s2 acceleration and an output power of 46 μW with a resistance of 4 kΩ.
4. Roundy, S., in the article which was written in 2005: different vibration energy harvester configurations were investigated and compared. In addition, the theoretical background of most of the present systems was given in order to explain the efficiency increase associated with the coupling coefficients. Maximum theoretical power density based on a range of commonly occurring vibrations were presented. Estimations range from 0.5 to 100mW/cm3 for vibrations in the range of 1–10 m/s2 at 50–350 Hz.
By examining all of these articles, I learned about the usage of energy harvesters in microsystems and their main working principle which helped me substantially in the brainstorming stage of my project. My system had to be versatile due to the fact that trees have a multimodal distribution of very low frequencies. In this manner, these papers had a major impact on the design of my experimental setup, the optimization processes and theoretical calculations.
In a world changing constantly, the rise of the microsystems could be seen clearly in many areas such as agriculture. These microsystems used in many sectors require a type of energy harvester in order to maintain working non-stop. Hence, as a type of energy which is efficient in small scales, vibrations have started to be worked on more and more day by day. The research conducted mainly provides the recent work carried out in the vibration energy harvesting area.
Firstly; the research was done, the first prototype was prepared and tested. Due to the low power output of the first prototype, optimization was carried out both theoretically and experimentally. In order to determine the appropriate parameters to be focused on, the working principle of the system was investigated. The system's working principle mainly depends on damped harmonic motion, piezoelectricity, and electromagnetism. And by examining all of these aspects theoretically, it was decided to keep both natural and applied frequency high. In order to assure these calculations, experiments were carried out on the cantilever beam length, tip mass, magnets, coil length and the number of turns in the coil. The experiments were taken with the LabJack digital oscilloscope and graphed on the Excel software.
In the experiments, 4 small cylindrical magnets with a maximum flux density of 0.3T were used initially. However, in order to achieve the maximum change of magnetic flux, it is necessary to have stronger magnets with more flux. For this reason, while the system was being optimized, two large 0.5T cylindrical magnets were used. In addition, the diameters of the magnets were kept close to the inner diameter of the coils, allowing more magnetic flux to pass through the coils.
CANTILEVER BEAM LENGTH
As is known, the natural frequency is affected by three parameters: 1-Tip mass, 2-Length of the cantilever beam, 3-Elastic constant of the cantilever beam. In order to examine the effect of the cantilever beam’s length on the generated voltage, experiments were carried out with 6, 7, 8, 9 cm long cantilever beams, respectively.
Another factor that affects the natural frequency of the cantilever beam is the tip mass. Therefore, to study the effect of tip mass, experiments were carried out by using tip masses of 25g (Magnets' own mass), 25 + 3g, 25 + 5g respectively. 8cm long cantilever beam was taken as the reference.
Our system has two different coil configurations located horizontally and vertically. For the optimizations of the coils, various experiments were carried out in order to examine the effect of the number of turns in the coil and coil length on the energy produced.
As is known, trees have a multimodal distribution of very low frequencies which in return decreases the energy generated. In order to increase this applied frequency, a gear system was designed and attached to the cantilever system.
Our system has an energy output which is sinusoidal. For the system to be able to charge a battery, DC output is required. In order to achieve a DC signal, a rectifying circuit was designed. The circuits installed for each coil are connected to each other, and in this way, the system charges faster. The final specifications are presented below.
TOTAL POWER OUTPUT OF THE SYSTEM
Power measurement was taken with the final setup. Here, the ambient vibration was taken as 1 Hz. In this case, the vibration was converted to 12Hz by the gear system. The length of the cantilever beam is 8 cm. The number of turns of the coils on the sides is 1000 each, the lengths are 3cm and the wire thicknesses are 0.6 mm. The number of turns of the upper and lower coils is 450 each, the lengths are 2cm and the wire thicknesses are 0.6 mm. The efficiency of the circuit was found to be 56%.
As can be seen in this graph, there is a total of 60.9mW of usable power generation, 48mW from 1st coil configuration, 11.6mW from 2nd coil configuration and 1.3mW from piezoelectric material. The power generation range of the piezoelectric material is from 0.1mW to 2.1mW obtained from the product datasheet. Therefore, it is possible to increase the generated power by creating a multilayer structure from these piezo modules. The total hourly power of the system is 60.9mWh, resulting in an energy output of 219.24 J per hour. With continuous vibration, it can fully charge a 2100 mAh NiMH battery in 51.7 hours. The hourly power consumption of the system is 4.5mWh. In this case, the energy generated by our system in 1 hour is able to operate the humidity-temperature measurement system for 13.5 hours.
Once we attached our system to the tree and performed humidity and temperature measurement with the DHT11 sensor, the data we obtained was transferred to the phone with the HC-06 Bluetooth module. Data was received by “Bluetooth Terminal” application on an Android phone.
2)Air Quality Measurement
Air quality was measured via the MQ-135 module and graphed on an online IOT platform "thingspeak.com". The data transmission was carried out with the ESP-8266 Wi-Fi module. This way, anyone who has access to the IOT platform can see the real-time data from anywhere with internet connection.
3)Fire Detection System
Fire detection was carried out with the Arduino flame detector module. The data was sent to the user via the HC-06 Bluetooth module.
4)Soil Moisture Measurement
Soil moisture was measured via the FC-28 soil moisture module. Data was transmitted with the HC-05 Bluetooth module to another module which can irrigate the area.
For pest detection, an Arduino camera, OV7670 was used. And it is aimed to image process the gathered photos of the area. The pest detection system is still in the development stage and is soon to be finished.
COMPARISON OF EXPERIMENTS WITH THEORETICAL CALCULATIONS
All of the graphs of the experiments carried out were compared to the calculated time constant values. This way the accuracy of our system has been shown theoretically.
In this project, a new eco-friendly digital agriculture module was designed. Our design consists of two magnets, four coils (two types), piezoelectric material, metal cantilever beam, a circuit, agricultural measurement module, plastic structure, rechargable batteries, gear system and a transmitter. In the first stage, a generator was developed using a single coil system. The working principle of the system is based on the energy production from the piezoelectric material and induction by the movement of the magnets attached to the cantilever beam between the coils. Experiments were carried out on the trees in the school garden with our initial generator setup. Optimization of the single coil configuration has been studied and the optimum number of coil turns, coil length, cantilever beam length and tip mass have been determined. In the second stage, this design was developed and piezoelectric material and second coil configuration were added and optimized. At this point, the amount of energy produced was increased, humidity and temperature values were obtained.
We believe that our system prototype, which we have completed with an average cost of about 192.19TL/$36,24 /€31,83, is a design that will generate more energy compared to the other examples in the literature and will be an alternative for battery-free, wireless sensor networks. Other features of the system are given below:
· It has many areas of usage.
· There is a potential to find usage in wireless sensor networks.
· It has no problems such as; day-night and dustiness.
· Helps to harvest energy from vibrating external energy sources.
· Production is simple.
· Non-linear characteristics.
· Hybrid system.
· It opens the way to digital agriculture.
· The power of the system is 60.9 mW at 1 Hz ambient vibration.
· The energy generated in 1 hour is able to operate the system for 13.5 hours.
· Designed to measure agricultural parameters and to transmit them wirelessly.
Our innovation in this work is the creation of a new eco-friendly system prototype that has higher power than other examples and is designed for applications with more energy needs by combining different electromagnetic and piezoelectric systems. The examples shown here are adapted to microsystems. However, with our work, systems with higher energy needs can also work. In addition, with the gear system used, vibration in any direction can be used. By adapting our system on a tree from an environmental point of view, we aimed to use it in agriculture for energy production and agricultural measurements. Vibrations are everywhere.
Hello! My name is Tuan and I'm a grade 11 student currently attending Private Cakabey Schools in Turkey. I love reading books,playing guitar,coding,messing with math equations and thinking about complex physics problems. I cannot give a definite answer to my interest in STEM due to the fact that I have a dream of being an astrophysicist since I was 5 years old. Nevertheless, I've always been aware of the fact that even though my mind is up there beyond the stars, my feet stand on this beautiful planet. Thus, I take environmental problems seriously. In my high school years, I have joined many extra-curricular activities including research projects, science competitions, advanced university courses and submitting papers to journals. I have recently completed a university-level physics course, and since 2016 have been working in the Ege University Magneto-Optics Lab. In 2017, I published my first paper in an international journal. In addition, I presented 2 abstract publications in symposiums. I've been highly inspired by Isaac Newton and Albert Einstein.
In the future,I'm planning to do a triple major in physics,electrical engineering, and mathematics in a top university such as MIT. Afterward, I want to keep on with my academic work and become a professor. And while maintaining my professor status,I also want to start my own business for the space industry. To tell the truth, I don't believe in prizes changing lives but rather changing our lives getting us prizes as it can be in many of the famous scientists' lives.
In the project carried out, some specific lab instruments have been used (oscilloscope, multimeter, gaussmeter, and LCR meter) which do not threaten anyone's health in any manner. But in order to use the instruments properly, I have been instructed by the lab supervisor, Dr. Yavuz Ozturk.
Dr. Yavuz Ozturk's contact information is given below:
Phone Number: 0 232 311 5246
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We are thankful to Ege University which allows us to use their laboratories to perform our experiments. We also thank to Assist. Prof. Dr. Yavuz ÖZTÜRK and Çağatay Daşman for their valuable insights and experiences.