A piezoelectric generator in public transportation captures energy from vehicle vibrations through the principle of piezoelectricity. Piezoelectric materials are substances that can generate an electric charge in response to mechanical stress or vibration. This phenomenon occurs due to the arrangement of atoms within the material, which results in a polarization of charges when the material is subjected to mechanical strain.
Here's how a piezoelectric generator captures energy from vehicle vibrations in public transportation:
Placement of Piezoelectric Elements: Piezoelectric elements are strategically placed in areas of the vehicle where vibrations are prominent. These areas could include the suspension system, chassis, seats, or any other location where the vehicle experiences mechanical vibrations during its operation.
Mechanical Vibrations: As the public transportation vehicle moves, it encounters various sources of mechanical vibrations, such as road unevenness, engine vibrations, and passenger movement. These vibrations cause the piezoelectric elements to experience mechanical stress or strain.
Generation of Electric Charge: When the piezoelectric elements are subjected to mechanical stress, the internal polarization of the material changes, leading to the separation of electric charges. This separation of charges generates a small electric voltage across the material.
Energy Harvesting Circuit: The generated electric voltage is then directed to an energy harvesting circuit. This circuit is designed to efficiently collect and manage the generated electric charge. It typically includes components such as rectifiers, capacitors, and voltage regulators.
Storage of Energy: The energy harvesting circuit converts the alternating current (AC) generated by the piezoelectric elements into direct current (DC) and stores it in a storage device, such as a rechargeable battery or a supercapacitor. This energy can be accumulated over time as the vehicle continues to experience vibrations.
Utilization of Captured Energy: The stored energy can be used to power various onboard systems in the public transportation vehicle. These systems could include lighting, air conditioning, passenger information displays, or even charging ports for electronic devices.
It's important to note that the amount of energy generated by piezoelectric generators from vehicle vibrations is relatively small, and the efficiency of the energy conversion process is influenced by factors such as the type of piezoelectric material used, the design of the energy harvesting circuit, and the intensity and frequency of the vibrations. As a result, piezoelectric energy harvesting systems are often employed as supplementary sources of power to help improve energy efficiency and reduce the overall environmental impact of public transportation vehicles.