Feasibility on development of kinetic-energy harvesting floors

Abstract

Electricity consumption in big cities has been increasing, especially in crowded areas. Although there is a large amount of energy usage in such places, people can generate the unnoticeable electrical energy from their footsteps. This paper aims to present the feasibility on development of an energy harvesting floor—called Genpath—using a rotational electromagnetic (EM) technique to generate electricity from the human’s footsteps. The system in Genpath comprises two main parts: the EM generator and the power management and storage circuit. After stepping over the floor, a rack-pinion mechanism under the floor converses the linear translation from a footstep into the rotation to drive a DC-generator to generate electricity. The EM generator yields an average energy per footstep of about 199 mJ (or average power of 331 mW) and the maximal voltage of 19 V at the rated 140-Ω load resistance. This amount of energy is sufficient for low power consumption electrical devices. The efficiency of the EM generator in Genpath is 16.6% based on the power generation from the heel strike of the human’s walk of 2 W per step. Among overall energy generated by the generator, 68% of generated energy is stored in the 9-V rechargeable batteries and the rest is supplied to the 4-V, LED instantaneous loads. The power management and storage circuit consisting of the diodes and DC-DC buck voltage converters was successfully designed. With 54% efficiency of the circuit, the average energy per step of 169 mJ can be stored in the rechargeable battery, and the other 4.7 mJ can be supplied to the LED loads.