Scientists working as part of the Metrology for Energy Harvesting Project have developed a new model to deliver the maximum power output for piezoelectric energy harvesters.Piezoelectric energy harvesters utilise energy from unwanted mechanical vibrations at the micro scale, such as the rattling of an air conditioning duct or the movement of a bridge with passing traffic.
The technology could make industrial processes more efficient and open up applications in areas such as wireless sensor networks.
Systems usually comprise of vibrating cantilevers covered with a piezoelectric layer that converts mechanical strain into an electrical charge. Most developers cover the entire length of the cantilever with piezoelectric material in an attempt to maximise the conversion efficiency.However, scientists at the National Physical Laboratory (NPL), one of seven national measurement institutes involved in project, have discovered that this approach is counter productive.
Their research shows that due to the charge redistribution across the cantilever there is an internal loss of power of up to 25% of potential output. To counter this, the team has developed a model to show that more energy can be converted if the beam is only covered with piezoelectric for two thirds of its length.
As well as developing wireless sensor networks, researchers are targeting applications that range from the predictive maintenance of moving machine parts, to electronic devices that harvest their own wasted operational energy.
Markys Cain, Knowledge Leader at NPL, said: “The energy harvesting market was worth $605 million in 2010 but is predicted to reach $4.4 billion by the end of this decade. For the market to reach its true potential we need to develop the products that can guarantee a greater energy yield and drive industrial adoption of energy harvesting products.”
