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This investigation designed and tested a prototype system that would allow existing road infrastructure to be adapted to harvest waste kinetic energy from traffic. The system relies on piezoelectricity, the charge that occurs in specific materials when subject to strain. It consists of a piezoelectric speed ramp for harvesting impacts from slow-moving traffic in urban settings and a 'cat's eye' to absorb vibrations from fast-moving vehicles on motorways.
A small-scale speed ramp prototype was developed which incorporates piezoelectric diaphragms consisting of a piezoelectric ceramic film on a brass plate. The device was tested by measuring its power output after being impacted with increasing quantities of kinetic energy and repeating the process using increasing numbers of diaphragms. It was found that the addition of diaphragms maximises energy absorption. After optimisation, allowing the device to hold more diaphragms, continued testing found that with twenty diaphragms, it could produce c. 810 µW of power when impacted with 3.34 J. As each diaphragm contains just 0.8 g of piezoelectric ceramic, huge potential was indicated for wide-scale implementation using much larger masses.
A prototype piezoelectric cat’s eye which absorbs vibrations imparted by vehicles on the surrounding road surface is now in development. Its ability is being tested currently by stimulation with vibration from increasing distances.
Together, if implemented on a large scale, these two devices form a system which is suitable for harvesting energy from all forms of traffic. Given the possibilities posed during testing, it is crystal-clear how this system could help to slow down the energy crisis.
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