A magnetostrictive system in wind turbine blades converts wind-induced vibrations into electricity through the principle of magnetostriction. Magnetostriction is a phenomenon where certain materials change their shape or dimensions when exposed to a magnetic field.
The system typically consists of three main components:
Magnetostrictive material: This is a specialized material with magnetostrictive properties, meaning it can change its shape when subjected to a magnetic field. Common magnetostrictive materials include Terfenol-D, which is an alloy of terbium, dysprosium, and iron.
Coils and magnets: The wind turbine blade is equipped with coils of wire and permanent magnets. The coils are wound around the magnetostrictive material, and the permanent magnets are positioned nearby.
Wind-induced vibrations: As the wind blows against the wind turbine blades, it induces vibrations in the structure. These vibrations cause the magnetostrictive material to experience mechanical stress and strain, leading to changes in its shape.
Here's how the conversion process works:
Mechanical deformation: When the wind-induced vibrations cause the blade to vibrate, the magnetostrictive material experiences mechanical deformation due to its magnetostrictive properties. The material stretches or compresses slightly in response to the vibration.
Induced magnetic field: The mechanical deformation of the magnetostrictive material causes changes in the magnetic flux within the material.
Electromagnetic induction: As the magnetic field changes, it induces an electric current in the surrounding coils of wire (Faraday's law of electromagnetic induction). The induced electric current is proportional to the rate of change of the magnetic field, which, in turn, is influenced by the wind-induced vibrations.
Electricity generation: The induced electric current is then collected and fed into the wind turbine's electrical system. It is converted and regulated to match the turbine's output voltage and frequency, making it suitable for feeding into the power grid or for local use.
By harnessing the wind-induced vibrations in the blades, the magnetostrictive system can generate additional electricity without significantly impacting the overall operation of the wind turbine. This technology can help improve the overall efficiency and power output of wind turbines, contributing to more sustainable energy generation from wind resources.