Generating Direct Current Electricity from Dripping or Flowing Ionic Water

Abstract Generation of electricity from flowing salt water is extremely attractive as the resources are abundant and green. We propose a generator to harvest DC electricity from flowing ionic solution. The device consists of a substrate with fixed surface charges, a top electrode and a bottom electrode separated with a distance. The electrostatic field originated from the surface charges separates charges of opposite polarities in the solution, while the flow directs the charges to different electrodes in a closed circuit. By utilizing ultrahigh charge density of ferroelectric substrate and ionic solution, the device produces pulsed DC output for droplets and constant current for continuous flow. The output could be greatly enhanced by using substrates with high surface charge densities and high ion concentration solutions. It could also be scaled up by connecting the devices in series or parallel. This work provides a new strategy to harvest low hydrodynamic energy from sea.