What is piezoelectric power ?

Piezoelectric energy harvesting is a technique that involves converting mechanical vibrations or movements into electrical energy using materials with piezoelectric properties. Piezoelectric materials generate an electric charge in response to mechanical stress, and this property can be harnessed to generate electrical power for various applications. This technique is particularly useful in scenarios where there are intermittent or low levels of ambient energy that can be harnessed and converted into electrical power for small-scale applications.

Piezoelectric energy harvesting has been applied in various scenarios as follows.

  • Harvesting Vibrations: Piezoelectric devices can be embedded in structures that experience vibrations, such as machinery, bridges, or even clothing. The vibrations deform the piezoelectric material, generating electricity.
  • Human Motion Harvesting: Piezoelectric materials can be integrated into wearable devices to harvest energy from the movements of the human body, such as walking or bending.
  • Environmental Vibrations: Piezoelectric devices can be deployed in environments where there are constant vibrations, like in urban areas with vehicular traffic, to generate power.

Piezoelectric energy harvesting

How piezoelectric energy harvesting works

The figure depicts block diagram of piezoelectric power harvesting. Following points illustrate step wise guide to working of piezoelectric harvesting technique.

  • The system uses Piezoelectric materials, which are substances that generate an electric charge in response to mechanical stress. Common piezoelectric materials include crystals like quartz, ceramics, and certain polymers.
  • The energy harvesting process begins with the application of mechanical stress to the piezoelectric material. This stress could be in the form of vibrations, deformations, or any mechanical force.
  • When mechanical stress is applied to the piezoelectric material, it causes the material's crystal lattice to deform. This results in the movement of charged particles within the material. This movement of charges creates an electric potential across the material, leading to the generation of an electric charge.
  • The generated electric charge is then harvested using electrodes attached to the piezoelectric material. These electrodes collect the charge and transfer it to an external circuit for storage or immediate use.
  • The harvested electrical energy is often in the form of an alternating current (AC). To make it more useful for most applications, a rectifier is employed to convert the AC into direct current (DC). The rectified DC can then be stored in a battery or a capacitor for later use.
  • The stored electrical energy can power low-power electronic devices or be used to charge batteries, providing a continuous and renewable source of power.

Advantages of piezoelectric energy harvesting

Following are the benefits or advantages of piezoelectric energy harvesting.

  1. The piezoelectric harvesting provides renewable and sustainable power source.
  2. Piezoelectric materials used in this harvesting can be integrated into variety of structures and devices. This makes them versatile for different applications.
  3. Piezoelectric devices are often solid state and do not have any moving parts. This leads to low maintenance requirements.
  4. Piezoelectric devices can operate in harsh environments and are relatively durable which makes them suitable for long term use with minimal intervention.
  5. The technique is beneficial where traditional power sources are impractical. Piezoelectric energy harvesting enables creation of self powered sensors and low power electronic devices.
  6. Piezoelectric harvesting is complement to other harvesting techniques such as solar or wind power. Hence hybrid harvesting solutions can provide more reliable and continuous energy supply.

Disadvantages of piezoelectric energy harvesting

Following are the limitations or disadvantages of piezoelectric energy harvesting.

  1. The energy density of piezoelectric materials is generally lower compared to other energy sources. Hence this technique is more suitable for low power applications and may not be practical for high power demanding devices or applications.
  2. Piezoelectric materials are sensitive to specific frequencies and mechanical amplitudes. This constraint limits their use.
  3. The effectiveness of piezoelectric energy harvesting is dependent on the availability of mechanical vibrations in the environment. In environments where vibrations are sporadic or weak, the energy harvesting efficiency may be insufficient to meet the power needs of the device.
  4. Integrating piezoelectric materials into existing structures or devices can be complex and may require careful design considerations.

Other energy harvesting techniques

Refer Energy Harvesting Methods which describes types and basics of energy harvesting techniques and energy harvesting materials. Refer RF Energy Harvesting system which describes RF energy harvesting.

RF and Wireless Terminologies