High-efficiency ballistic electrostatic generator using microdroplets

• Published in: Nature communications 2014-04, Vol.5 (1), p.3575-3575, Article 3575
• Main Authors: Xie, Yanbo, Bos, Diederik, de Vreede, Lennart J., de Boer, Hans L., van der Meulen, Mark-Jan, Versluis, Michel, Sprenkels, Ad J., van den Berg, Albert, Eijkel, Jan C. T.
• Format: Article
• Language: English
• Subjects: 142/126; 639/766/189; 639/766/25; Electrodes; Energy; Humanities and Social Sciences; multidisciplinary; Nanotechnology; Physics; Renewable resources; Science; Science (multidisciplinary); Silicon nitride
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms4575

The strong demand for renewable energy promotes research on novel methods and technologies for energy conversion. Microfluidic systems for energy conversion by streaming current are less known to the public, and the relatively low efficiencies previously obtained seemed to limit the further applications of such systems. Here we report a microdroplet-based electrostatic generator operating by an acceleration-deceleration cycle (‘ballistic’ conversion), and show that this principle enables both high efficiency and compact simple design. Water is accelerated by pumping it through a micropore to form a microjet breaking up into fast-moving charged droplets. Droplet kinetic energy is converted to electrical energy when the charged droplets decelerate in the electrical field that forms between membrane and target. We demonstrate conversion efficiencies of up to 48%, a power density of 160 kW m −2 and both high- (20 kV) and low- (500 V) voltage operation. Besides offering striking new insights, the device potentially opens up new perspectives for low-cost and robust renewable energy conversion. Fluidic energy conversion has been proposed as a renewable energy solution, but its conversion efficiency is low to date. Xie et al . improve the efficiency to 48% in a microfluidic electrostatic generator, which converts the kinetic energy of high-speed charged droplets to electricity.