A hybrid flow energy harvester using combined piezoelectric and electromagnetic transductions for pipeline network monitoring

An energy harvester that employs both electromagnetic and piezoelectric effects to convert fluid flow energy in the pipeline into electrical energy for powering wireless sensor nodes (WSNs) of the pipeline condition monitoring system has been developed. The devised hybrid energy harvester comprised a unimorph circular piezoelectric plate fixed in a T-joint, three stacked magnets attached at the middle of the piezoelectric plate, and an adjustable coil holder holding a wound coil. Experimental results of the developed prototype depict that it can produce a maximum load RMS voltage of 3.36 V with the piezoelectric part at 27 kΩ of optimal load resistance and 286 mV from the electromagnetic part at 335 Ω of optimum load resistance. Moreover, at 2.9 kPa flow pressure amplitude and 11.08 l/s flow rate, a maximum load power of 418 µW from the piezoelectric portion and 244 µW with the electromagnetic portion is produced. Upon integrating the harvester with a rectifier circuit, an open circuit DC voltage of 9.4 and 3.32 V are generated with piezoelectric and electromagnetic parts, respectively. Furthermore, under the same fluid flow condition, the piezoelectric part produces 404 µW DC power at 92 kΩ of optimum load resistance, while the electromagnetic portion produces 163 µW DC power at 10 kΩ of optimum load resistance. The developed harvester is also utilized to recharge a 4.8 V power bank from 1.11 to 4.2 V in 210 min. Moreover, it is also integrated with a pipeline condition monitoring system to power a WSN, a controller, and relevant circuitry.