Acoustic energy harvesting using electrochemical double layor capacitors: Technical feasibility and performance assessment

This paper describes a first prototype harvesting the acoustic energy using electrochemical storage devices. In particular, the harvesting system is composed by an Electrochemical Double Layer Capacitors (EDLC) suitably coupled with an electroacoustic absorber by means of an AC/DC converter. The aims of the proposed work are i) to assess the technical feasibility to compensate the decay voltage via an acoustic harvester; and ii) to evaluate how such compensation can improve the performance of the targeted EDLC. Concerning the first aim, the experimental results show that the required sound pressures to charge the EDLC up to its nominal voltage range from 118 dB up to 122 dB (re. 20 μPa). The EDLC charging times range from couple of hours up to several hours. The charging powers range from few mW up to several tens of mW and the energy efficiency of the whole system ranges from 5% up to 35%. Concerning the second aim of the paper, further experimental results illustrate a non-negligible improvement of the capability of the EDLC to deliver high-pulsed currents. In particular, after compensating the EDLC decay voltage via the proposed acoustic harvester, the rise time required to deliver a high pulse current is even 170% lower than the one obtained without any previous decay voltage compensation. The associated current peak value and root mean square value are 20 % higher.