A piezoelectric generator in public transportation captures energy from vehicle vibrations through a phenomenon called the piezoelectric effect. The piezoelectric effect is a property of certain materials that generate an electric charge in response to mechanical stress or deformation. In the context of public transportation, such as buses, trains, or trams, the vibrations and movements generated during operation can be harnessed to generate electrical energy.
Here's how a piezoelectric generator works to capture energy from vehicle vibrations:
Piezoelectric Material Selection: A suitable piezoelectric material is chosen based on its ability to efficiently convert mechanical vibrations into electrical energy. Common piezoelectric materials include crystals like quartz, ceramics like lead zirconate titanate (PZT), and polymers.
Placement of Piezoelectric Elements: Piezoelectric elements or sensors are strategically placed at locations on the vehicle where vibrations are significant, such as under seats, on the vehicle floor, or even within the suspension system. These elements can be embedded in flexible pads or strips to maximize their exposure to vibrations.
Mechanical Stress Generation: As the vehicle moves and experiences vibrations due to road conditions, acceleration, deceleration, and other dynamic forces, the piezoelectric elements are subjected to mechanical stress or deformation. This stress causes the piezoelectric material's crystal lattice structure to change, leading to the generation of electrical charges.
Electric Charge Generation: The mechanical stress causes the piezoelectric material to polarize, separating positive and negative charges within the material. This polarization generates an electric potential difference (voltage) across the material, creating an electric charge.
Energy Harvesting Circuitry: The generated electric charge is then harvested using specialized circuitry. This circuitry typically includes rectifiers and energy storage components, such as capacitors or batteries, to convert the alternating current (AC) generated by the piezoelectric material into direct current (DC) and store the captured energy.
Energy Utilization: The harvested electrical energy can be used to power various systems within the public transportation vehicle, such as lighting, sensors, displays, or even charging passenger devices.
It's important to note that while piezoelectric generators can capture energy from vehicle vibrations, the amount of energy generated is relatively small compared to the overall energy requirements of the vehicle. However, when integrated into a larger energy harvesting system, along with other renewable energy sources, such as solar panels or regenerative braking systems, piezoelectric generators can contribute to reducing energy consumption and improving the overall sustainability of public transportation systems.