Otago Polytechnic
ABE profile CharlotteFlaherty 003

Current conversion

In future a portable power generator might use water to charge your phone.

Can the kinetic energy of flowing water be used to generate electricity on a small scale? That was the challenge Engineering Technology student Charlotte Flaherty set herself for her final year project. The goal was to design and build a low-tech low-cost portable microgenerator that could charge a small battery.  This would reduce dependence on the national grid, and help people cope in an emergency affecting the grid such as storm or earthquake damage.

The key concept was using piezoelectric material, which generates an electrical current from  movement. Charlotte's project was supported by one of our Electrical Engineering staff, Mike Keppel, as well as her Mechanical Engineering supervisor Matt King. She also worked with our EPICentre technicians William Early and Ken Wyber and Neville Auton.

Charlotte's first design was a flow sock that would move like kelp in a stream of water, however she found that the sock's slow undulating movements were unsuitable because the piezoelectric material works optimally with faster movements. Charlotte then turned to consider several different paddle designs. Rotating like a waterwheel, the paddles repeatedly struck the strips of piezoelectric material. The electric current generated was very small so further development is needed to meet Charlotte's goal of charging a battery.