Using the gravitational energy of water to generate power by separation of charge at interfaces

Abstract

When water droplets (e.g., from rain) flow down a solid surface due to gravity, they can generate power.

Slide electrification: charging of surfaces by moving water drops

“…With respect to applications, the motivation is to convert the kinetic energy of a flowing liquid directly to electrical energy. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] To this end, much literature has focused on how charging affects the dynamic wetting of surfaces, the movement of drops, and contact angle hysteresis. [17][18][19][20] However, the efficiency of charge separation by flowing liquids is still much lower than that of conventional electric generators.…”

Solid‐to‐Liquid Charge Transfer for Generating Droplets with Tunable Charge

“…[1][2][3][4][5][6][7][8] In these applications,t he liquid droplets are usually charged by ahigh-voltage power supply.Liquid can also be charged using other methods;examples include pressure-driven flows across initially uncharged channels (e.g., from millimeters to nanometers in size), [9][10][11][12] electrostatic induction (e.g., the Kelvin water dropper), and electrostatic charging of jumping droplets. [1][2][3][4][5][6][7][8] In these applications,t he liquid droplets are usually charged by ahigh-voltage power supply.Liquid can also be charged using other methods;examples include pressure-driven flows across initially uncharged channels (e.g., from millimeters to nanometers in size), [9][10][11][12] electrostatic induction (e.g., the Kelvin water dropper), and electrostatic charging of jumping droplets.…”

“…ForP DMS, we found that the results are qualitatively similar to the case of nylon-the charge of the water droplet is approximately linearly proportional to the charge of PDMS (Figure 2b). [9,24] Hence,i ts eems that aw ater droplet can be charged either positively or negatively by ap iece of negatively charged PTFE, depending on the amount of negative charge the piece of PTFE has. Previous studies have shown that an uncharged solid surface can charge water droplets positively.…”

“…Electrically charged droplets are useful in aw ide variety of applications,i ncluding ink-jet printing, electrospray ionization for mass spectrometry,s crubbers for removing particulates in an air stream, and fabrication of materials (e.g., nano-scale materials and particles for drug delivery). [1][2][3][4][5][6][7][8] In these applications,t he liquid droplets are usually charged by ahigh-voltage power supply.Liquid can also be charged using other methods;examples include pressure-driven flows across initially uncharged channels (e.g., from millimeters to nanometers in size), [9][10][11][12] electrostatic induction (e.g., the Kelvin water dropper), and electrostatic charging of jumping droplets. [13] These methods,h owever, either require an external power supply,a re technically challenging to operate,o ra re unable to control the charge of the liquid.…”

“…Previous studies have shown that an uncharged solid surface can charge water droplets positively. [9,24] Hence,i ts eems that aw ater droplet can be charged either positively or negatively by ap iece of negatively charged PTFE, depending on the amount of negative charge the piece of PTFE has.…”