INTRODUCTION
Problem statement
Energy is fundamentally the capacity to perform work, with electricity being the most prevalent form of energy utilized in everyday life As the demand for energy continues to rise, it has become essential for daily living This project aims to address the growing need for sustainable energy solutions by developing a device capable of generating electricity from human movement, particularly through footsteps.
The urgency of addressing energy generation is critical, as various sources such as coal, natural gas, petroleum, and nuclear power contribute to our electricity supply However, these energy sources often come with significant environmental drawbacks, particularly air pollution Notably, coal energy production has emerged as a major contributor to global warming, highlighting the need for more sustainable alternatives in our energy landscape.
The search for alternative energy sources is becoming increasingly urgent as conventional energy supplies diminish While solar energy is often proposed as a solution, its high costs and limited availability during rainy and winter seasons make it an unreliable option Therefore, it is essential to explore other sustainable energy alternatives to meet growing demands.
Electricity is a vital resource for humanity, making it essential to harness wasted energy effectively Walking, a common human activity, generates energy loss in the form of vibrations on the ground This project explores the conversion of this wasted energy into electricity, showcasing its potential applications in high-traffic areas like educational institutions, universities, train stations, airports, shopping malls, and pedestrian streets By utilizing the energy produced during walking or running, we can enhance energy efficiency in these environments.
Figure 1.5: Application of Footstep Generation
Description of the Project
Renewable energy solutions like piezoelectricity present an excellent opportunity for domestic applications by harnessing the energy generated from walking As pedestrian activity rises, the piezoelectric effect—where specific materials generate electric charge in response to mechanical stress—can convert this wasted energy into electricity This method not only offers a sustainable and limitless energy source but is also environmentally friendly, making it an ideal choice for clean energy initiatives.
Benefits of the system
Piezoelectricity stands out from thermal energy, biomass production, and hydro energy as it generates no pollution and poses no harm to the environment.
Piezoelectricity offers a sustainable solution by utilizing land efficiently without the need for extensive rehabilitation or destruction By installing piezoelectric tiles underground, this technology encourages population growth in the area rather than displacing residents, promoting a harmonious coexistence with the environment.
Independence in conditions weather: Is functional on sunny, cloudy, dry, windy and wet days
Objectives
The aim of this research is to harvest energy from footstep using piezoelectric disk based on the concept of polarization The objectives of the study are as follow:
To produce renewable electricity from footstep using piezoelectric disk placed along a pathway.
To reduce the cost for power generation besides increasing the efficiency of power generation
To replace with available energy sources through human movement
To protect the natural environment beside that improving health through physical activities
BACKGROUND CONTENT
Introduction to Piezoelectricity
The direct piezoelectric effect was discovered in 1880 by brothers Pierre and Jacques Curie They combined their expertise in pyroelectricity with insights into crystal structures, successfully demonstrating the piezoelectric effect using various crystals, including tourmaline, quartz, topaz, cane sugar, and Rochelle salt.
The piezoelectric effect finds many applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, high voltage and power sources, sensor, piezoelectric sensor,
Piezoelectricity, known as the piezoelectric effect, encompasses two key properties: the capability of specific materials to produce an alternating current (AC) voltage when subjected to stress, and the converse phenomenon where stress is generated upon the application of an electric field This dual functionality makes piezoelectric materials valuable for power harvesting applications.
Figure 2.1: Piezoelectric effect when creating pressure
When piezoelectric material is placed under mechanical stress, a shifting of the positive and negative charge centres in the material takes place, which then results in an external electrical field.
When reversed, an outer electrical field either stretches or compresses the piezoelectric material.
Various materials, both natural and synthetic, demonstrate piezoelectric effects Notable naturally occurring piezoelectric materials include Berlinite, cane sugar, quartz, Rochelle salt, topaz, tourmaline, and dry bone, which exhibits piezoelectric properties due to apatite crystals and is believed to function as a biological force sensor.
The Piezoelectric sensor exhibits unique characteristics, as varying forces applied to the piezo material generate different voltage readings The complexity of voltage and current values increases when the sensors are connected in series or parallel, influenced by the applied forces and the specific piezoelectric material used Figure 2.4 illustrates the voltage and current values for each connection, revealing that the voltage for both configurations is minimal, necessitating the use of multiple sensors for effective measurement.
Figure 2.4: Value of Piezoelectric sensor of each connection
The graph illustrates that while a series connection provides high voltage, it results in low current Conversely, a parallel connection yields good current but with lower voltage However, a series-parallel connection effectively resolves this issue, delivering both optimal voltage and current.
To address the voltage issue in both connections, it is essential to utilize a series-parallel combination This configuration, as illustrated in Figure 2.5, ensures an optimal voltage and current ratio while simultaneously decreasing the overall resistance of the circuit.
Figure 2.5: Value of the series-parallel connection
Full-wave bridge rectifier
This project involves an electronic circuit that utilizes a DC power supply to operate essential electronic components from the available AC mains supply To achieve the conversion from AC to DC, a full-wave bridge rectifier is employed, which consists of four diodes arranged in a closed-loop configuration to efficiently transform the input AC into a DC output The principle of the full-wave bridge rectifier ensures effective conversion, making it a vital component in power supply applications.
During the positive half-cycle of the input, D1 and D2 are forward-bias and conduct current D3 and D4 are reverse bias.
During the negative half-cycle of the input, D3 and D4 are forward-bias and conduct current D1 and D2 are reverse bias.
The advantage of full-wave bridge rectifier:
Don’t need a center-tapped (CT) so the price is low cost
A bridge rectifier enables electric current to flow during both the positive and negative half cycles of an AC input signal, resulting in an output DC signal that closely resembles the input.
The DC output signal of the bridge rectifier is smoother than the output DC signal of a half-wave rectifier.
The efficiency of the bridge rectifier is higher than the efficiency of a half-wave rectifier
Boost converter
A boost DC voltage converter circuit is composed of four essential electronic components: an inductor (L), a semiconductor switch (S), a diode (D), and a capacitor (C) The input DC voltage source connects to the inductor, while the MOSFET switch operates by opening and closing based on the gate terminal's signal; it closes when a high-level square wave is applied and opens when the signal is low.
The MOSFET enables electrical conduction, linking the inductor L's right end to the power supply's negative terminal, which initiates a current flow between the positive and negative terminals This current gradually increases from an initial value, allowing the inductor to store energy as a magnetic field During this phase, minimal current circulates in the rest of the circuit since diode D1 is reverse biased, effectively disconnecting the load circuit from the power source E.
Figure 2.9: When MOSFET switch on
When the MOSFET is turned off, the circuit becomes active, causing an inductive voltage across the coil L that opposes the reduction in current This voltage has a polarity opposite to that when the MOSFET conducts, resulting in two voltages in series: the supply voltage (VIN) and the voltage (VL) across the coil The combined voltage (VIN + VL) forward-biases the diode D, allowing the generated current to flow through D and charge the capacitor C to a value of VIN + VL, minus the voltage drop across D, while simultaneously powering the load.
Voltage regulator circuit
A voltage regulator is a crucial component in power supply systems, ensuring a stable output voltage despite fluctuations in input voltage Various types of voltage regulators, including Zener, series, shunt, fixed positive, IC, adjustable, negative, and dual tracking, are available to maintain a consistent DC output voltage These regulators effectively manage changes in both input voltage and load conditions, providing reliable performance in power electronics.
In this project, we use a series voltage regulator.
The block diagram in Figure 2.10 illustrates the fundamental configuration of a series regulator circuit, where the series element regulates the input voltage delivered to the output A feedback circuit samples the output voltage and compares it to a reference voltage, ensuring precise voltage regulation.
When the output voltage rises, the comparator circuit generates a control signal that prompts the series control element to reduce the output voltage, ensuring stable voltage levels.
When the output voltage drops, the comparator circuit generates a control signal that prompts the series control element to boost the output voltage, ensuring consistent voltage levels.
Figure 2.10: Series regulator block diagram
DESIGN AND IMPLEMENTATION
Block diagram
Figure 3.1: Block diagram of Footstep power generation
Figure 3.1 illustrates the block diagram of a footstep power generation system, which comprises several key components: a piezoelectric material sensor, a full wave bridge, a boost converter, a voltage regulator circuit, and a charge circuit.
Piezoelectric materials function as sensors by converting applied pressure into electrical energy, with pressure sources including the weight of moving vehicles or pedestrians Each object produces varying energy levels, leading to an inconsistent output from the piezoelectric material To address this, a bridge circuit is employed to transform the variable voltage into a linear output Additionally, an AC ripple filter is utilized to eliminate fluctuations, resulting in a smoother wave representation.
The boost converter (step-up converter) is a DC-to-DC power converter that steps up voltage (while stepping down current) from its input (supply) to its output (load).
The voltage regulator circuit is a circuit that has the function of generating or maintaining a stable voltage even if the input changes over a wide range We can simply
14 understand that the voltage stabilizer circuit always has a stable output voltage no matter how the input voltage changes.
The main function of the charging circuit is to store electrical energy to provide lighting, automatically cut off when fully charged, short circuit protection, overload protection, overcurrent protection.
Principle of Footstep power generation
Piezoelectric materials generate electrical energy when pressure is applied, whether from moving vehicles or pedestrians Due to the low power output of individual piezo films, research has focused on combining multiple films to enhance energy generation Two different connection configurations were tested to evaluate their effectiveness.
Parallel and series connections of piezoelectric transducers yield different voltage outputs, with series connections providing increased voltage but not in a linear manner To achieve high current density, a combination of both connection types is utilized However, the alternating current generated is unsuitable for powering home appliances directly Therefore, a full-bridge rectifier, consisting of four diodes, is employed to convert the AC output into stable direct current The energy produced by the piezoelectric crystal is typically around 3 volts, which is insufficient to charge a 6V battery directly To address this, a boost converter circuit is implemented to elevate the voltage to 6 volts, enabling effective storage in a 6V battery.
The output of a bridge rectifier features undulating ripples over the DC voltage To achieve a more stable DC output, a simple Zener diode can be connected to the rectifier's output This setup not only allows for energy storage but also supports lighting applications effectively.
SIMULATION AND ANALYSIS
Boost converter
The figure 4.1 is the boost converter circuit After we connect the Piezoelectric sensor with full-wave bridge rectifier, we obtain direct current (DC),
The maximum voltage that the capacitor can operate must be bigger than voltage output.
Choose maximum voltage that the capacitor can operate: 100 (V)
The maximum voltage that the diode can operate must be bigger than voltage output.
Choose diode which , maximum voltage that the capacitor can operate: 60 (V)
Oscillating circuit
In the oscillating circuit, we use IC 555 According Texas Instrument’s company, we obtain the circuit.
Series regulator circuit
Before connect series regulator circuit When connect series regulator circuit
Simulation
Figure 4.4: Connection of Piezoelectric sensor
Figure 4.7: The voltage after boost
Figure 4.8: The voltage after regulator
RESULT AND CONCLUSION
The simulation circuit demonstrates that varying gravitational forces on the sensor result in different voltage levels However, these voltage levels are very low, necessitating a booster and voltage stabilizer circuit to charge a storage battery, which in turn supplies electricity for lighting operations.
In conclusion, our project highlights the immense potential of harnessing wasted kinetic energy as a sustainable and environmentally friendly energy source This innovative approach can generate significant electrical energy, particularly in densely populated areas, making it ideal for applications such as street lighting and charging ports without the need for extensive power lines Additionally, it can enhance the illumination of buildings along pavements, promoting energy efficiency and convenience in urban settings.
Power generation is simply walking or running.
Considered as available, clean energy and friendly with environment
Energy saving and easy maintenance
Battery is used to store the generated power.
Only applicable for the particular place.
Initial cost of this arrangement is high.
Mechanical moving part is high.
Care should be taken for batteries.