Ballistic Energy Conversion with 78% Efficiency and System Integration

Electrokinetic energy conversion by streaming current was proposed for energy harvesting for >50 years; however, it proved to be of limited use due to low efficiencies. The recent emergence of nanomaterials and related technologies significantly increased these efficiencies. Here, we report an electrokinetic energy conversion system using a single stream of ballistic droplets from which we obtain close to 80% efficiency with 25 kV generated voltage. The voltage can be reduced to a minimum of 4 kV while maintaining ∼40% efficiency, a promising feature from the point of view of applications. Furthermore, we investigate the possibility of integration with 9 microjets as a conversion unit, which generates 1.9 mW with an efficiency of 35%. We experimentally achieve a power density of 8.4 kW/m2 under 0.4 bar pressure and an upper limit of 84 kW/m2 using denser pore arrays. Our results demonstrate efficient ballistic energy conversion, as well as the potential for integrated applications.